Class ^ >f Book at&S. KJ W$t l&ural Science Series Edited by L. H. Bailey THE FEEDING OF ANIMALS C&e l&utal Science &me$ The Soil. The Spraying of Plants. Milk and its Products. The Fertility of the Land. The Principles of Fruit-Growing. Bush-Fruits. Fertilizers. The Principles of Agriculture. Irrigation and Drainage. The Farmstead. Rural Wealth and Welfare. The Principles of Vegetable-Gardening. Farm Poultry. The Feeding of Animals. THE FEEDING OF ANIMALS BY WHITMAN HOWARD JORDAN Director of the New York Agricultural Experiment Station SEGQ&JJl PDITWN. \ ? - i ■ . ■ j£eto Sotfe THE MACMILLAN COMPANY LONDON: MACMILLAN & CO., Ltd. 1903 All rights reserved je'i Copyright, 1901 By THE MACMILLAN COMPANY Set up and electrotyped June, 1901 Reprinted September, 1903 lunt U^leassant Wte** J. Horace McFarland Company Harrisburg • Pennsylvania J PREFACE This volume is the result of an effort to present the main facts and principles fundamental to the art of feeding animals, as they are now understood. It is not a statement of rules or of the details of practice, for even if the author regarded himself as competent to discuss these he would hold it to be unwise to attempt to discriminate in practical matters so varied and so complex. Neither has an effort been made to harmonize the whole mass of experimental data relating to animal nutrition. Many of these data are of no value, many are very incomplete, and many are apparently con- flicting, so that more useful lessons can often be drawn from single events in the field of experiment and investigation than from the frequently doubtful testimony of summaries. The author expresses the hope that what he has written will not be regarded as having for its ulti- mate object the mere exposition of feeding formulas. It is to be feared that the German standard rations are unfortunately accepted by many as nutrition pre- rv) vi Preface scriptions "to be given according to directions." It is time to break away, if we have not already done so, from an undiscriminating adherence to mathe- matical doses of nutrients, the accuracy of which is supposed by some to outweigh all other consider- ations and to determine success in feeding. The study of animal nutrition may not wisely center around feeding standards, as seems to have been the tendency of late years. While these formulas are certainly an aid in selecting adequate and uniform rations, the} 7 are nevertheless merely an imperfect expression of relations not fully understood that have a greatly variable application in practice, an appli- cation judiciously made only through the exercise of a judgment enlightened by familiarity with funda- mental facts and principles. Rational cattle feeding is not to be attained through a blind acceptance of existing standard rations but by means of a broad understanding of the scientific and practical knowl- edge in which these standards had their rise. Much of the matter introduced in this connection bears no immediate relation to the practical opera- tions of feeding. No apology is made for this de- parture from the business aspects of the subject. A study of the practical relations of science should not only promote our material well-being but should also lend itself to intellectual stimulus and culture. Preface vii The chapter on The Feeding of Poultry was writ- ten by Mr. William P. Wheeler, who also executed the several drawings which appear as illustrations. The author is under great obligations to his associ- ates, Dr. L. L. Van Slyke and Mr. Frank H. Hall, for reading the proof sheets. W. H. JORDAN. New York State Experiment Station, Geneva, N. Y., June 1, 1901. CONTENTS PART I THE PRINCIPLES OF FEEDING CHAPTER I PAGES Introduction: Man's Relation to Animal Life 1-6 The conditions and problems involved in feeding animals . . 3 CHAPTER II The Relations of Plant and Animal Life 7-10 CHAPTER III The Chemical Elements of Nutrition 11-24 The elements and their sources: Carbon, Oxygen, Hy- drogen, Nitrogen, Sulfur, Phosphorus, Chlorine, Potassium, Sodium, Calcium, Iron 12 Proportions of elements in plants and animals 21 In plan s 21 In animals 22 CHAPTER IV The Compounds of Animal Nutrition 25-50 Classes of matter 26 (ix) Contents PAGES The classes of compounds 28 Water 30 Water in living plants 33 Water in feeding stuffs 36 Water in the animal 38 Ash 41 The mineral compounds of plants 43 Variations due to species 43 The distribution of mineral compounds in the dif- ferent parts of the plant 45 Influence of manufacturing processes on the ash constituents 47 The mineral compounds of animal bodies .... 48 The distribution of inorganic compounds in the animal body , 49 CHAPTER V The Compounds of Animal Nutrition (continued) . . . 51-70 The nitrogen compounds 51 Protein 52 The proteids 55 The albuminoids 57 The albumins 58 The globulins 59 The modified albuminoids 62 Coagulating ferments 63 Heat 64 Action of acids and alkalies 65 Ferments of digestion 65 Combinations 66 The gelatinoids 68 Keratin and similar substances 69 Protein: The non- proteids 69 Amides 69 Extractives 70 Contents xi CHAPTER VI PAGES The Compounds of Animal Nutrition (concluded) . . . 71-92 The nitrogen -free compounds 71 Crude fiber 72 Nitrogen-free extract 74 The starches 75 The vegetable gums 78 The pectin bodies 80 The sugars , 80 The acids 83 Animal carbohydrates 84 Chemical relations and characteristics of the carbohy- drates 85 Fats or oils 88 CHAPTER VII The Composition of the Bodies of Farm Animals . . . 93-97 CHAPTER VIII The Digestion of Food 98-125 Ferments 99 The mouth 104 The stomach 108 The intestines 114 Absorption of the food 119 Feces 121 Relation of the different feeding stuff compounds to the digestive processes 121 CHAPTER IX Conditions Influencing Digestion 126-141 Palatableness 126 Influence of quantity of ration 127 xii Contents PAGES Effect of drying fodders 128 Influence of the conditions and methods of preserving fodders 129 Influence of the stage of growth of the plant 130 Influence of methods of preparation of food 131 Influence of grinding 133 Effect of common salt • 133 Influence of frequency of feeding and watering animals . 134 Influence of certain other conditions 134 Influence of the combination of food nutrients 135 Conditions pertaining to the animal : species, breed, age and individuality 137 Determination of digestibility 139 CHAPTER X The Distribution and Use of the Digested Food . . 142-150 The blood 142 The heart 144 The lungs 146 The use of food 147 Elimination of wastes 148 The liver 150 CHAPTER XI The Functions op the Nutrients 151-169 Functions of the mineral compounds of the food .... 152 Functions of protein 153 Functions of carbohydrates 155 Functions of the fats and oils 157 Food a3 a source of energy 157 Available energy 163 Net energy 164 Energy relations of the several nutrients 166 Heat relations 167 Contents xiii CHAPTER XII PAGES Physiological Values of the Nutrients 170-181 Relative energy and production values of the nutrients, singly and as classes 171 Relative energy values 171 Relative production values of the different nutrients . 175 Relative importance of the protein compounds .... 178 CHAPTER XIII Laws of Nutrition 182-185 CHAPTER XIV Sources of Knowledge 186-202 Conclusions of practice 187 Practical feeding experiments 188 Chemical and physiological studies 191 More accurate methods of investigation 192 Relation of food to production 194 The respiration apparatus 196 Determination of energy values 198 Calculation of energy value of a ration 198 Energy value of digested nutrients 199 Measurement of food combustion 200 Respiration calorimeter 201 PART II THE PRACTICE OF FEEDING CHAPTER XV Cattle Foods — Natural Products 203-226 Forage crops 204 Green vs. dried fodders 205 The harvesting of forage crops 207 XIV Contents PAGES Silage 212 Nature of changes in silo 213 Extent of loss in the silo 215 Ensiling vs. field-curing 217 Crops for ensilage 218 Construction of silos 219 Filling the silo 220 The straws 223 l Roots and tubers 224 Grains and seeds 225 CHAPTER XVI Cattle Foods — Commercial" Feeding Stuffs 227-257 Classes of commercial by-product feeding stuffs 228 Wheat offals 228 Residues from breakfast foods 232 Brewers' by-products 236 Residues from starch and glucose manufacture .... 236 Residues from the manufacture of beet -sugar .... 240 The oil meals in general 241 Cottonseed meal 242 Linseed meal 245 Chemical distinctions in cattle foods 248 Coarse foods vs. grains and grain products 249 Classification according to the proportions of nutrients . 249 Foods of animal origin 252 Milk 252 Dairy by-products » . . 254 Slaughter-house and other animal refuses 256 CHAPTER XVII The Production of Cattle Foods 258-267 Soiling crops 263 Contents xv CHAPTER XVIII PAGES The Valuation of Feeding Stuffs 268-279 Commercial values 269 Physiological values 272 Selection of feeding stuffs 273 Other standards of valuation 277 CHAPTER XIX The Selection and Compounding of Rations 280-294 CHAPTER XX Maintenance Rations 295-303 Maintenance food for bovines 297 Maintenance food for horses 300 CHAPTER XXI Milk Production 304-323 Milk secretion 306 Sources of milk solids 307 The rate of formation of milk solids 308 The amount and character of the ration for milk production 309 The sources of protein for milk production 313 The relation of food to the composition and quality of milk 316 Effect of food upon the composition of milk 316 Effect of food upon the flavors of milk and its products . 321 CHAPTER XXII Feeding Growing Animals 324-338 The feeding of calves 328 The feeding of lambs 331 Feeding colts . . . 333 Feeding the dam ' . 334 Feeding the colt 335 xvi Contents CHAPTER XXIII PAGES Feeding Animals for the Production of Meat .... 339-366 The nature and extent of the growth in beef production . 340 The food needs of the fattening steer . . , 341 The selection of a fattening ration 347 Mutton production 349 The nature and extent of the growth in fattening sheep . 350 Food needs of fattening sheep . . 351 The selection of a ration for sheep 355 Pork production 357 Character of the growth in pork production 358 Food requirements for pork production . 360 Feeding the dam 360 Feeding pigs for the market 361 CHAPTER XXIV Feeding Working Animals 367-378 The horse a machine 367 The work performed by a horse 368 The food requirements of a working horse 371 Source of the ration for working horses 374 CHAPTER XXV The Feeding of Poultry — By William P. Wheeler . . 379-399 Kinds of foods 379 Incidental effects of the food 382 Digestive apparatus 383 Constituents of the body 387 Necessity for considering the water 389 The organic and mineral nutrients in food 389 The study of rations and deduction of standards .... 392 Maintenance rations 393 Rations for laying hens 393 Rations for young birds 394 Contents xvii CHAPTER XXVI PAGES The Relation of Food to Production 400-407 CHAPTER XXVII General Management 408-418 Selection of animals 409 Selection of cows 409 The selection of animals for meat production .... 411 Manipulation of the ration 413 Quantity of the ration 414 Environment and treatment of animals 415 APPENDIX Composition and Digestion Tables 419-443 1. Average composition of American feeding stuffs . . 419-427 2. Average coefficients of digestion 427-435 3. Feeding standards 435-438 4. Fertilizing constituents, American feeding stuffs . 439-443 INDEX 445-450 APR 1 1 1904 THE FEEDING OF ANIMALS PART I— THE PRINCIPLES OF FEEDING CHAPTER I INTRODUCTION: MANS RELATION TO ANIMAL LIFE There was a time somewhere in the dim past when the beast of the field knew no master. The only obe- dience which he rendered to a superior power was an unconscious submission to Nature's stern forces. He wandered forth at will to find in the untilled pastures such food as the wild herbage afforded, and, unre- strained, he sought a place of rest in the tangled thicket. He knew no refuge from the winter's cold and storm but some sheltered nook or forest recess to which his brute intelligence guided him, and he was his own defense against the dangers which beset him. Man had not come to be a controlling factor in the development of the various forms of animal life. If the brute knew him at all, it was as the huntsman, as an enemy, but not as a superior to whom must be paid a tribute of service or of food and clothing. The wild ox and horse possessed those characteristics which best fitted them to cope with the untoward conditions of their environment; but there had not yet appeared A (1) 2 The Feeding of Animals those specialized capacities of growth, draft, speed or production which now render these animals so very valuable for the service and sustenance of the human family. The qualities developed were those demanded by the necessities of existence without reference to utility as measured by the needs of a higher form of life. The fiber of the body must possess endurance, and it mat- tered little whether or not the muscle could furnish a juicy steak. The brute mother must defend her young and supply it with milk, and this being accomplished, her maternal functions ceased. She was neither so endowed that she could open the fountains of her life to feed generously a not too grateful master, nor so submissive that she would. The wild horse must be fleet and en- during that he might escape the enemy, but not that he might bear heavy burdens or win a contest in the prescribed form of the race- track. In the lapse of centuries there have been many changes in the relation of man to the animal creation. Bird and beast in various forms have come to minister to man's wants, and in their present domesticated con- dition are, in their turn, utterly dependent upon him for the food and shelter which are necessary to their physical welfare, or even existence. It is not too much to assert that the domestic animal, in the artificial en- vironment imposed upon it, is entirely at man's mercy, even in the development of those attributes and char- acteristics which otherwise would be determined by the demands of an unaided warfare with nature. The juicy sirloin of the shorthorn, the almost abnormal milk Man Improves the Animal 3 glands of the champion butter cow, the delicate fiber of merino wool, and the marvelous speed of the modern race-horse are evidences of man's skill in recasting natural types into forms of greater usefulness to him. From the animal of nature, under the direction of a higher intelligence, has proceeded the animal of civil- ization, an organism obedient to the environment which has been created for it. This interdependence of man and the lower orders of life has a vast economic significance. A large part of human activity is devoted to the production and transportation of food for animals and to the traffic in the products of the dairy, slaughter-house and sheep- fold, and to their utilization in various ways. The prosperity of every farm is maintained to a greater or less extent by feeding domestic animals, and our rail- roads, our markets, in fact, nearly all our important business enterprises, are more or less dependent upon the extent and prosperity of animal husbandry. THE CONDITIONS AND PROBLEMS INVOLVED IN FEEDING ANIMALS The first and simplest form of animal husbandry is that which was practiced by the nomad. His flocks and herds subsisted wholly by grazing and were moved from place to place according to the supply of forage afforded by different localities. No shelter was pro- vided for the animals and no food was stored for their use. The only intelligence or special knowledge that was brought to bear upon the business of the herdsman 4 The Feeding of Animals was a familiarity with the traditions and superstitions touching the care of cattle and the acquaintance which a roving life would give with the pastures furnishing the most abundant and sweetest wild grasses during the various seasons of the year. There was not then even a dim promise of the modern traffic in meats or of the fine art of dairying as we now know it. As man began to give up this wandering life, erect permanent dwellings and confine his ownership of land to definite limits, he acquired the art of tillage, not only that he might have food for his family but also for his cattle. He then began to store fodder in stacks, and later in barns, to meet the demands of the inclement portions of the year. For centuries, however, grazing was the chief de- pendence for securing the production of meat and milk because the foods supplied during the cold season were not in such abundance or so nutritious as to sustain continuous growth or milk secretion. Even within the remembrance of men now living, live stock was not ex- pected to produce an increase during the winter months but was simply maintained from autumn until spring in order that profits might be realized from summer pasturage. Formerly the demands of the market were much simpler than they are now. Butter and cheese were produced almost wholly from summer dairying, and no such variety of fresh meats was offered to con- sumers during the entire year as is now the case. But great changes have occurred during the last fifty years, more especially during the past twenty -five. First of all, we have a modern type of animal, greatly unlike that The Animal of Civilization 5 of previous times. The ideal dairy cow of to-day is a high -pressure milk machine extremely sensitive to her environment and demanding a degree of care in manage- ment and feeding, if she is to do her safe maximum work, which was not necessary with coarser and less deli- cate organisms. Every successful dairyman must now provide proper winter quarters for his herd and through- out the entire year must supply rations that will sup- port continuous, generous production. He must do this, too, by the use of a greater variety of foods than was formerly available. Not only has the number of useful forage crops greatty increased, but the average farmer no longer produces all the food which his ani- mals consume. He now buys numerous kinds of com- mercial feeding stuffs. These purchased materials are not wholly the cereal grains whose value through long experience has come to be measured by certain prac- tical standards, but they consist in part of compara- tively new by-products from the manufacture of oils, starch and human food preparations, — feeding stuffs which differ greatly in their nutritive properties. Be- sides all these changes, animal husbandry is now called upon as never before to feed the prosperous part of humanity with high -class products having special qual- ities of texture and flavor that depend to some extent upon feeding. Certainly the conditions and problems to be met in this branch of human industry have grown more and more complex. We must add to this the fact that, as is true with every department of man's activity, science has laid her hands upon the business of the farmer and has 6 The Feeding of Animals forced him into a new range of thought and practice. This influx of knowledge has greatly influenced the requirements for meeting a sharpened competition and has rendered it imperative for the practitioner to bring to bear upon a great variety of agricultural problems a clear understanding of fundamental facts and prin- ciples. The feeding of animals involves many difficult ques- tions. These begin with the production of forage and grain crops where it is necessary to discover what ones will yield the largest food values per unit of expendi- ture. Economy demands that the several feeding stuffs which are at command shall be so combined that there shall be no waste of material or energy. With several considerations in view, a decision must be reached as to the most profitable commercial foods to purchase when the number is large and the range of prices is wide. The influence of the various foods upon the quality of the product, especially dairy products, has in recent years become an important matter. These and related problems confront the stockman and dairy- man, and they demand for their wise solution more than what is ordinarily designated as practical experience. The investigator who shall successfully inquire into these matters must possess scientific qualifications of a high order; and the practical man, who, in a busi- ness way, conforms his methods to the highest stand- ard which scientific research has already made possible must be familiar with the knowledge fundamental to the feeder's art. CHAPTER II THE RELATIONS OF PLANT AND ANIMAL LIFE The foundations of animal life are laid in the plant, and with the plant must begin a study of the funda- mental facts of animal nutrition. The first step toward supplying animals with food is taken when the farmer drops seed into the warm earth. As soon as the young rootlets from a germinating seed come in contact with the soil and the first leaves reach the air, assimilative growth begins. 'During the hours of sunlight matter is constantly gathered in an invisible way, which, after transformation into various compounds, is added to the enlarging tissues of the plant. This continues, per- haps for a season, until the stalk of grain has reached its full height and has attained the ultimate object of its existence in the production of seed, or it may go on for centuries, so that where now is only the acorn there will be the giant oak. The farmer car- ries to the field a few pounds of seed and he returns to his storehouses laden with tons of new material, perhaps hay, perhaps grain. From somewhere, in some way, the plant has gathered various substances, often no less than ten thousand pounds per acre in a single year, and has manufactured them into forms that are useful to the husbandman. (7) 8 The Feeding of Animals Plant life not only builds tissue: it stores energy, as we may easily discover. The farmer's boy learns this when he feels the hot glow of the fire that is fed by forest wood. The wood disappears, but he is warmed by the radiant energy. It has occurred that when fuel was scarce and costly and grain was abun- dant and cheap, the western farmer has burned his corn. All he realized in this case for his labor was the warmth which was necessary to make himself and family comfortable. As with the wood, the materials which were collected from the soil and air have been dis- persed in invisible forms during the combustion which liberated the heat energy, except a small heap of ashes on the hearth. The farmers who raised corn for fuel were no richer in storehouse or in pocket. They had simply used an available supply of heat, derived from the energy which was stored in the plant during its growth. But ordinarily, grass and grain are produced, not for fuel but for food purposes, and in this use of vege- table matter we come in contact with a set of phe- nomena equally complex and equally important and interesting to those of its growth. The calf of to-day weighing, perhaps, a hundred pounds, becomes in a few years the immense bullock. What is the source Of this mass of bone and flesh ? It is merely plant sub- stance which in other combinations was collected from soil and air. This animal eats his daily ration and makes his daily gain of tissue. When his food is with- held, his body wastes and he dies. If his food varies in amount, his growth is somewhat proportional to the Tlit Role of the Plant 9 quantity eaten. We, therefore, cannot resist the con- clusion that the bones, blood and flesh of this ox are derived from what he eats. The plant does more than to supply building ma- terial for the animal body. This living organism is kept warm. No matter how cold the surrounding at- mosphere, we find by the use of a thermometer that in health the ox's temperature remains at about 101° F., with but small variation. Just as the western farmer obtained heat by burning corn in the fireplace, so does the cattle -owner maintain the body temperature of his animals at the necessary degree by supplying food to be burned. The combustion is not so rapid as occurs in the fireplace, still the changes are the same but more slowly carried on. Food not only builds the ox and warms him, — it furnishes him with motive power. The energy which the plant acquires during its time of growth is, through his vital processes, transformed in part into motion. The animal is a living mechanism, a combination of muscles and levers which are moved not by means of a spontaneous internal generation of energy, but through a supply from without, the energy stored in the plant. If we use the plant for fuel we get heat alone; if we feed it to the animals we get heat, motion and the production of other forms of matter that have a rela- tively high commercial value. In the first instance the plant substance, except the mineral portion, is wholly broken up into simpler compounds which in unseen gaseous forms escape from our possession, the 10 The Feeding of Animals liberated energy becoming manifest as heat. With the animal, a greatly varying proportion of the dry matter of the plant is retained to form his body substance, and the remaining part suffers decomposition, largely into the same compounds that are carried away by the draft from the fire on the hearth. As a result there is built a living organism that is warmed to a tempera- ture generally much above that of the surrounding air, which is the seat of complex internal activities and is capable of performing external work. CHAPTER III THE CHEMICAL ELEMENTS OF ANIMAL NUTRITION The facts which are fundamentally necessary to a broad understanding of the economy of cattle feeding, pertain, first of all, to the materials out of which vege- table and animal tissues are constructed. It is impor- tant to know both what these are and what are their sources. About seventy substances are now believed to be chemical elements, i. e., substances that cannot be re- solved into two or more simpler ones, and of which, so far as known, all forms of matter are composed, the variety of combinations being almost infinite. It is remarkable that comparatively few of these fundamental substances, — about one-fifth, — are intimately related to the growth of plants; and those that occupy a promi- nent place in animal nutrition are even less in number. It is necessary to mention only fifteen elements in this connection, some of which are of minor impor- tance: carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, chlorine, silicon, fluorine, potassium, so- dium, calcium, magnesium, iron and manganese. At ordinary temperatures, four of these, oxygen, hydrogen, nitrogen and chlorine, are gases, and the re- maining ones are solids. Four are constant and im- (11) 12 The Feeding of Animals portant ingredients of the atmosphere; viz., carbon, oxygen, hydrogen and nitrogen, and they also exist in the soil in gases, as well as in combination in liquids and solids; the other eleven, though sometimes present in the air in minute quantities, are found to no appre- ciable extent except as fixed compounds in water and in the crust of the earth, or in plants and animals. Nearly all of these elementary substances are absolutely essential to the existence of animal life as now con- stituted. From the standpoint of necessity, they are, therefore, nearly all of equal value, but if we take into consideration the relative ease and abundance of the supply, certain ones rise to a position of supreme im- portance. THE ELEMENTS AND THEIR SOURCES Carbon. — This is a familiar substance in common life. Anthracite coal and charcoal are examples of im- pure carbon. Graphite in lead pencils is also carbon, and so are diamonds. When wood chars or food is burned in an overheated oven the partially decomposed materials become black, revealing the presence of car- bon, the other elements with which it was associated being driven out. The humus of the soil is vegetable matter, which, from other causes, has undergone some- what the same change. An immense quantity of carbon exists in the air, combined with oxygen as carbon dioxid or carbonic acid gas. The average proportion by weight of this compound in the atmosphere is stated to be .06 per Carbon 13 cent, and as the weight of a column of air one inch square is fifteen pounds, it follows that over every acre of land there is 28.2 tons of carbon dioxid, or 7.7 tons of carbon. As we know that plants draw their supply of this element from the atmosphere, and as vegetable tissue is its only source to the animal, we are able to assert, with confidence, that the carbon in the tissues of animal life was once floating in space. A long time ago, Boussingault determined the aver- age yearly amount of carbon which was withdrawn from the air by the crops grown on a particular field during a period of five years, and found it to be 4,615 pounds. This is no more than is acquired by a large crop of maize. As a matter of fact, plants, as well as animals, contain a larger proportion of this element than of any other, and the amount of this substance which enters into the processes of growth and decay in the vegetable and animal kingdoms is almost beyond comprehension. It is natural to wonder whether the atmospheric supply is equal to the demand. Any anxieties we may have con- cerning this should be removed by learning that during many years the percentage of atmospheric carbon has not changed appreciably. The processes of decay on the earth's surface, the combustion of wood and coal as fuel and of carbon compounds by animal life are re- turning carbon to the air as rapidly as it is being with- drawn. This is the round traveled, — from the air to the plant, from the plant to the animal, and from the animal back to the air, — a cycle in which this element has been moving since life began, and in which it will continue to move so long as life exists. 14 The Feeding of Animals Oxygen. — This element is, next to carbon, the most abundant component of vegetable and animal tissues, and it stands second to none in its relation to the vital processes of nearly all forms of life. It is not a sub- stance with which we are familiar by sight, because we ordinarily come in contact with it as a transparent, colorless gas. We live and move in it, for it is an im- portant and uniformly abundant constituent of the at- mosphere. The air is over one-fifth oxygen by volume, the proportion by weight being slightly larger. More than twenty -one million pounds of this element are contained in the air above a single acre of land, a quantity which remains remarkably constant, and which is surprisingly uniform over the entire surface of the globe. While it is being continuously withdrawn from the air for the uses of life and to maintain fuel com- bustion and processes of decay, it is, like carbon, as continuously returned. Vast quantities of oxygen are also contained in water, as this compound, which fills the ocean and lakes, and is abundant in the crust of the earth, is nearly 89 per cent oxygen. It is estimated also that the solids in the crust of the earth are one -half oxy- gen. That which enters directly into the uses of ani- mal life is, however, chiefly that which is derived from the atmosphere and water. Not a plant grows or animal lives excepting through the circulation of oxj^gen, during which it passes into fixed combinations and back again to the free form. The animal uses the free oxygen in breathing and re- turns it to the air in part combined with carbon as car- Oxygen — Hydrogen 1 5 bonic acid, This compound the plant appropriates, re- taining the carbon for its tissues and giving back the uncombined oxygen to the atmosphere to be again used by animals. All decay and many other chemical changes require the presence of this element. What we speak of as fire is due to its union with the ele- ments of the fuel. It bears an indispensable rela- tion to the mechanical forces that man now employs, for it is the agent which maintains combustion in the furnaces of our industries. All the activities of life are intimately related to it. When a plant grows, oxy- gen is torn from its union with other elements by the dominating power of the sun's rays, and energy is stored in vegetable tissue. When this tissue is used as food the oxygen returns to its former combinations through the opportunities offered by the vital pro- cesses of the animal, and the hidden forces of the plant compounds are thus manifested in a variety of ways. The animal labors and man toils and thinks because of the energy thus stored and liberated. Hydrogen. — This element, which, in a free state, is the lightest known gas, is found abundantly in na- ture only in combination with other elements. The minute quantities which exist in the air are due to volcanic action and possibly to decay under certain conditions. As a manufactured product, it has an im- portant use in producing intense heat and in filling bal- loons. Hydrogen constitutes about one -ninth of water by weight, and is found in a large number of soil com- pounds. It is an essential constituent of vegetable and animal tissues, although it exists in the compounds 16 The Feeding of Animals of living organisms in a much smaller proportion than carbon or oxygen. Plants obtain it largely from water, and it is furnished to the animal body in water and in other compounds. Nitrogen. — Probably no element has been given more attention in its relations to agriculture from the scientific and practical standpoints than has nitrogen as such and in its compounds. Like oxygen it is an invisible, tasteless, and odorless gas which forms in the free state a large part of the earth's atmosphere. The air has been considered to be approximately 77 per cent free nitrogen by weight, but the discovery of the new element, argon, which has heretofore passed as nitrogen, will slightly modify previous determinations. Nowhere outside of the air and the tissues of living organisms does nitrogen exist in any form in compara- tively large quantities. The soil spaces contain it and it is taken into solution in small proportions in all natural waters. It is found in the mineral, as well as organic compounds of the soil, but in quantities which seem insignificant as compared with other elements, such as oxygen and silicon. Few agricultural soils contain over one -half of one per cent of combined nitrogen. Minute quantities of its compounds exist in the atmosphere which are being constantly carried to the soil in rain-water and as constantly replaced by the ammonia from decomposing animal and vegetable mat- ter and by the products of the oxidation of nitrogen through electrical action and combustion. Notwith- standing this comparatively small supply of nitrogen compounds, they play a prominent part in agriculture, Nitrogen 17 both commercially and physiologically. The nitrogen balance of the farm must be carefully considered both by the crop producer and by the cattle feeder. Nitrogen compounds are especially important be- cause the available supply is often dangerously near the demand or even below it. The nitrogen found in the air is inert for animal uses, and is ignored by a large majority of plants. Much of that in the soil is also unavailable. Moreover, its immediately useful com- pounds on the farm are constantly subject to loss, — first by processes of fermentation which the farmer cannot wholly prevent, and second by soil losses which are to some extent beyond control. Many of the com- mercial products of the farm also cany away much nitrogen. The sources of supply to balance this outgo are the nitric acid and ammonia of the rainfall, the free nitrogen captured by legumes and whatever comes from purchased fertilizers and foods. These facts relate primarily to plant production, but they also sustain an essential relation to the maintenance of animal life and cannot be ignored in a rational and w r ell- directed sys- tem of animal husbandry. Physiological^, the nitrogen compounds stand in the front rank. They are necessary building material for the fundamental tissues of the animal and are inti- mately related to the prominent chemical changes which are involved in growth and in the maintenance of life. It is safe to assert, too, that variations of these com- pounds in the food may have an important influence on the character of the body structure or on the amount of a particular product. B 18 The Feeding of Animals As a result of these conditions which relate to the supply of useful nitrogen and to its important role, we find that it has assumed a prominent place in com- merce. It is the most costly ingredient of fertilizers, and the value of commercial cattle foods is sometimes based almost wholly upon their content of this element. For these reasons, the control, even though only par- tial, which the farmer may now assume over the in- come and outgo of the nitrogen compounds valuable to agriculture is a triumph of modern science, and an important feature of rural economy. Sulfur is a common and familiar substance. As an element it is not widely distributed in nature, but its compounds are found in all soils and natural waters, and in all the higher forms of animal and vegetable life. We know it as "brimstone" when fused in sticks and as "flowers of sulfur" when in a finely divided form. Its most common commercial compounds are sulfuric acid and the sulfates of potash, soda, lime and mag- nesia. This element is an essential part of some of the most important tissues of the animal body, and is supplied in food in the form of the sulfates and in its proteid combinations. Phosphorus occupies an important place among the elements of nutrition. In the uncombined form it does not exist in nature, as that found in laboratories is produced only by chemical means. Its compounds are found everywhere. The phosphates of calcium, mag- nesium and iron are widely distributed in soils and large deposits of calcium phosphate are known, from which is obtained the crude phosphatic rock that serves Other Elements 19 as a basis for the manufacture of commercial fertilizers. All feeding stuffs in their natural forms contain phos- phorus, either as phosphates, or as combined in certain nitrogen compounds which stand in close relation to the vital processes. It is distributed in the flesh of animals, and combined with lime constitutes a large part of bone. Chlorine, which is a constituent of common salt, is essential to the nutrition of the animal. At ordinary temperatures it is, in the free state, a greenish -colored, disagreeable gas. When combined with hydrogen it forms hydrochloric acid, a compound which is necessary to th3 digestion of food. Any ordinary mixed ration contains this element in a quantity sufficient for the animal's needs. Potassium combined with oxygen and hydrogen gives us the caustic potash of the market. The ashes of all plants contain this element, a familiar illustra- tion of this fact being the potassium carbonate leached from wood ashes by hot water in the old-fashioned way of making soft soap. The saleratus formerly used in bread -making is a potassium compound. This element is found in the flesh of animals, mostly in the form of the phosphate, and is abundantly supplied for the pur- poses of nutrition by all feeding stuffs that are not by-products. Sodium is the basal element of common salt, and in this form it is very generally supplied to domestic ani- mals. In this connection, sodium chloride (common salt) is about the only sodium compound we need to mention, for this is the one that serves almost wholly 20 The Feeding of Animals as a source of this element to the animal whether it is supplied directly as such or is obtained from the food. Sodium plays an important part in the diges- tion of food, because it is the basis of certain bile salts and is concerned in other ways in the digestive processes. • Calcium, when united with oxygen, forms lime, which is one of our commonest commercial articles. Large masses of lime rock, or carbonate of lime, exist in many parts of the earth's surface, and every soil contains more or less of lime compounds. As com- pounds of this element are usually found in plants and in the milk of all animals, normal food nearly always furnishes a supply sufficient to meet the demands of animal life. The growing animal makes a generous use of lime, because in union with phosphoric acid it is the chief building material of the bony framework. A deficiency of food lime is sure to cause abnormal development of the bony structures. With birds, it is especially in demand during egg formation, egg shells being mostly a lime compound. Iron, one of the elements of living organisms, needs no description, because its common properties are fa- miliar to every one. Iron rust and iron ore are oxides of this element, and when the oxygen is removed from these, we have the bright gray metal of commerce. Though taken up by plants and animals in small quan- tities only, iron is absolutely essential to their growth and welfare, but because of its abundance the impera- tive character of the demand is never realized in ordi- nary experience. The Elements in Plants 21 PROPORTIONS OF THE ELEMENTS IN PLANTS AND ANIMALS The facts which have been reviewed concerning the elements out of which the tissues of plants and animals are built are properly supplemented by a statement of the proportions in which these are found in living or- ganisms. This information is necessary to an under- standing of the relations of supply and demand which exist between the vegetable and animal kingdoms and the raw materials of the inorganic world. In Plants. — It is estimated by a German scientist, Knop, that if all the species of the vegetable kingdom, exclusive of the fungi, were fused into one mass, the ultimate composition of the dry matter of this mixture would be the following: Per cent Carbon 45 Oxygen .... 42 Hydrogen 6.5 Nitrogen 1.5 Mineral compounds ( ash) 5 The composition of various single species or of parts of a plant, such as the fruit or straw, shows consid- erable variations from these average figures: Carbon Oxygen Hydrogen Nitrogen (Ash) Clover hay 47.4 37.8 5. 2.1 7.7 Wheat kernel 46.1 43.4 5.8 2.3 2.4 Wheat straw 48.4 38.9 5.3 .4 7.0 Fodder beets 42.8 43.4 5.8 1.7 6-3 Fodder beet leaves 38.1 30.8 5.1 4.5 21.5 22 The Feeding of Animals Carbon constitutes a larger proportion of the dry substance of plants than any other element, and there is certainly no species that is an exception to this rule. Oxygen stands next in order, followed by hydrogen, and then nitrogen. It is an important fact in the economy of nature that those elements which, on the average, make up 93.5 per cent of the dry matter of plants have as their main source either the atmosphere or water. Only a small percentage of the dry matter of the farmer's crops is drawn from the soil, and it there- fore follows that it is this small proportion of the mass of matter that makes up the inorganic world which sustains the most important economic and financial relations to the farmer's business. The elements of the ash vary somewhat in different plants. For illustration, their proportions in the dry matter of the maize plant in bloom are given in this connection: Per cent Phosphorus 26 Silicon 51 Sulfur 07 Chlorine 29 Potassium 1.78 Sodium 19 Calcium 72 Magnesium 39 Iron 10 Oxygen combined with the above 1.73 Total per cent 6.04 In animals. — We are not ignorant of the propor- tions of the chemical elements in the bodies of our Proportions of Chemical Elements 23 larger animals. Lawes and Gilbert, of England, and the Maine Experiment Station, in this country, have made analyses of the entire bodies, or nearly so, of steers and other domestic animals. These results, com- bined with our knowledge of the constitution of the compounds of the animal tissues, enable us to calcu- late very closely the proportions of carbon and other elements in the entire body of an ox: Fat ox Two steers, 2 yrs. old Lawes and Gilbert Maine Station Per cent Per cent Carbon 63 60 Oxygen 13.8 14.1 Hydrogen 9.4 9. Nitrogen 5. 5.8 Mineral compounds (ash) . 8.8 11.1 As the proportion of carbon is much larger in the fats than in the other compounds of the animal body, it is easy to see that the ultimate composition of the ox would vary with his condition, whether lean or very fat. The figures given suffice to show, however, that ani- mals, like plants, contain much more carbon than of any other element, and that the quantities of the re- maining elements stand in the same order in the plant and in the animal, the striking differences being the greater proportion of ox y gen in the former and of carbon and nitrogen in the latter. The plant and ani- mal are alike, therefore, in consisting chiefly of those elements which are derived from air and water. Car- bon, oxygen and hydrogen constitute from 83 to 86 per cent of the bodies of fat oxen and steers, raw materials which nature supplies without cost to the farmer, leav- 24 The Feeding of Animals ing less than one-sixth of the animal to be bnilt from elements that have, in part, a commercial value for crop production, which is the fundamental considera- tion in animal husbandry. As has been stated previously, one of these ele- ments, which in its various compounds bears a market value, is nitrogen. The others having commercial im- portance belong to what is termed the ash of the plant or animal. For this and other reasons it is desirable to consider the elements found in the ash or mineral portion of the animal body. We will return for this information to the analysis of a fat ox made by Lawes and Gilbert. These investigators found that the ash, constituting 8.8 per cent of the dry substance of the entire body, was made up as follows: Per cent Phosphorus 1.53 Calcium 2.80 Potassium . • . - .26 Sodium 20 Magnesium 07 Oxygen, combined with the above 3.29 Silicon, sulfur 65 8.80 Of the elements other than oxygen which appear in the ash, phosphorus and calcium take a leading place as to quantity, although sulfur, potassium and sodium are essential, even if present in relatively small amounts. Phosphorus, potassium and calcium have a commercial prominence in their agricultural relations, a fact which is to be considered chiefly in their uses as plant -foods. CHAPTER IV THE COMPOUNDS OF ANIMAL NUTRITION The animal body consists primarily of elements, but we ordinarily regard it as made up of compounds. These are groups of elements united in such fixed and constant proportions that they have as uniform proper- ties, under given conditions, as the elements themselves. In discussing the composition and uses of cattle foods and the structure, composition and functions of the animal as an organism, we refer chiefly to the com- pounds of carbon rather than to carbon itself. To be sure, the investigator of the problems of nutrition often conducts his researches and formulates his conclusions with reference to the elements, but when the informa- tion he secures reaches the language of practice, we speak of albuminoids, carbohydrates and fats. Com- merce recognizes these compounds also. It is necessary, therefore, for the student of animal nutrition, whether as a scientist or as one who would thoroughly under- stand the art of feeding, to become well informed about those substances that in various proportions form the organized structure of plants, and that furnish not only the energies that are manifested by animal life, but all the materials out of which the animal tissues are built. (25) 26 The Feeding of Animals CLASSES OF MATTER Before passing to a consideration in detail of the proximate constituents of plants and animals, it is de- sirable to reach a clear understanding of certain broad divisions into which we classify all matter, either living or dead, which has been organized by the vital forces of the various forms of life. One of the most common and familiar phenomena of the physical world is the destruction of vegetable or animal matter by combustion, with the result that only a small portion of the original material is left behind in visible and solid forms. Fuel, such as wood or coal, is largely consumed when ignited, and we have as a residue the ashes. If we incinerate hay, corn or wheat we get the same result. The gradual decomposition of exposed dead vegetable matter that occurs in warm weather is a process essentially similar to the com- bustion of fuel, only more prolonged. In view of these facts, it is customary to classify all the tissues of plants and animals into the combustible and incombus- tible portions, the former being that part of the ignited or decayed substance which disappears in the air as gases, and the latter the residue or ash. It should be well understood that combustion does not involve a loss of matter; only a change into other forms. If we w r ere to collect the gases which pass off from a stick of wood that is burned, consisting mostly of carbon dioxid, vapor of water, ammonia and, perhaps, certain other compounds of nitrogen, we would find that their total weight, plus that of the ash residue, is even greater Classes of Matter 27 than that of the dry wood, because the carbon and the hydrogen of the wood have taken to themselves from the air, during the combustion, an increased amount of oxygen. The carbon, oxygen, hydrogen and nitrogen of the plant or animal tissue belong to the combusti- ble portion, although small amounts of two of these elements are found in the ash, as it is usually esti- mated. The remainder of the fifteen elements previ- ously named are supposed to appear wholly in the ash. The relation in quantity of the combustible and in- combustible parts of vegetable and animal dry matter is illustrated below: Combustible Incombustible (Ash) Per cent Per cent Clover hay 92.8 7.2 Potato tubers 95.5 4-5 Maize kernel 98.3 1.7 Wheatkernel 98. 2. Body of fat ox 91.2 8.8 The significance of these facts in their relation to cattle feeding is, that the chemical change which we call combustion is one of the phenomena of animal nu- trition. Substances which may suffer either slow or rapid oxidation outside the animal may undergo com- plete or partial combustion in the animal; or, stated in another way, the part of the plant which "burns up" in the fireplace or crucible is the part which in general undergoes the same change within the animal organism in so far as the food is digested. The terms combustible and incombustible are less used, perhaps, than two others, which represent prac- 28 The Feeding of Animals tically the same divisions of plant or animal substance; viz., organic and inorganic. In chemical literature, the portion of a plant or animal which suffers combus- tion is called the organic, and the ash is known as the inorganic part. These terms are evidently based upon the erroneous assumption that the compounds which burn and break up into simpler ones are peculiarly those which sustain necessary and vital relations to life, and are formed through the functions of living organ- isms. To be sure, the dry substance of the plant is organized chiefly by building up compounds of carbon, oxygen, hydrogen and nitrogen, which suffer combus- tion; but compounds of sulfur, phosphorus, chlorine, potassium, sodium and calcium are also constant and essential constituents of the juices and tissues of the plant and animal; and, although the latter elements may finally wholly appear in the incombustible part or ash, they have, nevertheless, sustained in other com- binations important relations to nutrition and growth. It is true, however, that the portion of a food material which is commonly spoken of as organic embraces those compounds that furnish practically all the energy which is utilized by animal life and much the larger part of the building material. THE CLASSES OF COMPOUNDS The known compounds that belong to life in all its forms are almost innumerable, and doubtless many are yet to be discovered. These sustain a variety of re- lations to human needs, some serving as food, some Classes of Compounds 29 as medicine and some in the arts. It is fortunate that comparatively few must be considered in dis- cussing the science and art of cattle -feeding. More- over, it is convenient that the compounds which play a leading part in animal nutrition are designated, es- pecially for practical purposes, in classes rather than singly, even though this custom tends to more or less looseness of expression and definition. The same classification is used for the compounds of both the vegetable and animal kingdoms, and it is now customary to divide them into the following groups : Water, Ash (mineral compounds), Protein (nitrogenous compounds), Carbohydrates (and related bodies), Fats (or oils). In this instance, accuracy is sacrificed to conven- ience. The class names have come to be regarded, more or less, as representing entities having fixed prop- erties and functions, whereas each class contains numer- ous compounds differing widely in their characteristics and in their nutritive value and office. Moreover, these terms have a variable significance as used under differ- ent conditions. No one of them except water uniformly represents just the same mixture of compounds when applied to unlike feeding stuffs. Before passing to a detailed description of these com- pounds, singly or in groups, it will be well to gain a clear understanding of the relation which the fifteen ele- ments mentioned sustain to these classes of substances. This can be seen most readily by a tabular display: 30 The Feeding of Animals All vegeta ble or ani mal matter . Incombustible or inorganic matter . . . Water Ash Combustible or organic matter . . . Protein f Oxygen \ Hydrogen ' Oxygen Sulfur Chlorine Phosphorus Silicon. Fluorine Potassium Sodium Calcium Magnesium Iron Manganese Carbon Oxygen Hydrogen Nitrogen Sulfur (generally) Phosphorus (sometimes) Iron (in a few cases) Carbohydrates f Carbon and fats . . 1 Oxygen L Hydrogen The ash, which, on the average, constitutes about one- twentieth of the plant, and never more than one -tenth of the animal, may contain thirteen of the fifteen elements, while the larger proportion of living matter consists mostly of the compounds of three or four ele- ments, in no case of more than six or seven. From this point of view, it becomes strikingly evident that the dominant elements of life, quantity alone consid- ered, are those derived from the air and water. WATER Water fills a very important place in agriculture. It is everywhere present, generally in some useful way. All plant substance, all animal tissue, foods and nearly Water in Organic Substance 31 all the material things with which man comes in contact in his daily life are made up of more or less water, or are associated with it. Sometimes this is very evident, as with green plants or juicy fruits. It is not so evident with straw and cornmeal. If, however, we submit almost any substance, no matter how dry it may appear, except perhaps, glass and metals, to the heat of an oven at 212° F., we find that a material loss of weight occurs: and if we so arrange that whatever is driven off is first drawn through some substance that entirely absorbs the water which has been vapor- ized, we learn that the decrease in weight is nearly all accounted for by the water thus collected. This fact suggests to us the chemist's way of deter- mining the proportion of water which any particular material contains. He weighs out a certain amount of the substance and then keeps it in an oven at 212° F. for five hours perhaps, after which it is re- weighed. The difference in the two weights, or the loss, is assumed to be all water, and the percentage in the original substance is easily calculated. That por- tion of the material which is left behind after the water is evaporated, we call the dry substance. Water is associated with plant and animal tissues in two ways, hygroscopically and physiologically. It is easy to illustrate the former way by an object lesson. If an ounce of cornmeal were to be dried in an oven as described, it would, as stated, lose in weight. If it were subsequently allowed to remain exposed in the open air in a barn or out of doors, it would return quite or nearly to its original weight. The loss would 32 The Feeding of Animals be due to water driven out, and the gain to water ab- sorbed from the atmosphere, which we call h} r groscopic moisture. All solids attract moisture up to a certain propor- tion, which varies with the substance and with the conditions that prevail. The surfaces of the particles of matter are ordinarily covered with a thin film of water, which is thicker on a cold, wet day than on a warm, dry day, and so the same quantity of hay or grain weighs less at one time than at another, because the percentage of hygroscopic water varies. An equi- librium will always be established between the attrac- tion of a substance for moisture and the tension of the vapor of water in the surrounding air, which accounts for the effect of temperature and of the degree to which the air is saturated with water vapor. As all substances do not have the same attraction for moisture, therefore, under similar atmospheric condi- tions, one feeding stuff may retain more water than another. Water that is held physiologically is that which is a constant and essential part of living organisms, in which relation it is necessary to life and performs certain important functions. These functions are of three kinds: (1) The presence of water in the tis- sues of plants and animals gives them more or less firmness or rigidity combined with elasticity; (2) water acts as a food solvent; (3) water is the great carrier of food materials and of waste products from one part to another of the vegetable or animal or- ganism. Water in Plants 33 Water in living plants. — Water constitutes a large proportion of the weight of all living plants, especially during the period of active growth. The cured hay, as any farmer's boy knows, weighs much less than did the green grass when it was cut, and this loss in weight is due almost wholly to evaporation of water from the tissues of the plant under the influence of the sun and wind. This water, which is contained in the tubes and inter- cellular spaces of the stalk or leaf, is exactly the same chemical compound as pure water found anywhere else, and has no more value for the animal, excepting that it is pure and is not subject to the contamination which sometimes occurs in streams and wells. There is no such thing as the so-called natural water of plants, and which has a peculiar nutritive value or function. Vege- tation water should be distinguished from sap or plant juice. Sap is more than water; it is water holding in solution certain substances such as sugars and min- eral salts. When the plant is dried, these soluble com- pounds do not pass off, but remain behind as part of the dry matter. The proportion of water in plants varies greatly in different species, and in the same species according to the stage of growth or the surrounding conditions. These facts have more importance than is generally recognized, because the food value of vegetable sub- stances is influenced by the proportion of dry matter. It is always necessary to know the percentage of water in a green plant before we can estimate its worth for feeding purposes. The variations in water content of the living tissues 34 The Feeding of Animals of different species of plants or parts of plants is well illustrated by the following figures: Water in green plants Per cent Pasture grass (mixed) 80 Timothy grass 61.6 Oats (fodder) 62.2 Rye (fodder) 76.6 Sorghum (fodder) 79.4 Fodder corn, dent, kernels glazed 73.4 Fodder corn, flint, kernels glazed 77.1 Red clover 70.8 Alfalfa 71.8 Horse bean 84.2 Potatoes (tubers) 78.9 Beets (mangels) 90.9 Turnips 90.5 Immature plants contain more water than older or mature ones. Young pasture grass is more largely water than the same plants would be after the seed is formed. TLis iact is consistent with the very rapid transference of building material during the active stages of growth. Analyses of samples of timothy grass cut at the Maine State College in 1879, and at the Pennsylvania State College in 1881 show the marked inthience of the stage of growth upon the water content of the living plant: Maine State College Timothy Percentage of water Nearly headed out 78.7 In full blossom 71.9 Out of blossom 65.2 Nearly ripe 63.3 Water in Plants 35 Pennsylvania State College Percentage of water Highly No manured manure Cut June 6, heads just appearing 79.7 76.5 Cut June 23, just beginning to bloom 69.7 69.1 Cut July 5, somewhat past full bloom 61.4 60 What is true of timothy is probably true of all forage crops iu the perfectly fresh state. We have here au explanation of the difficulty of curing earty cut grass. When the farmer begins haying, at least two drying days are needed in order to secure a product that will not ferment in the mow, while later in the season, grass cut in the morning may be safely stored in the mow before night. At the Maine State College in 1880, immature timothy grass lost 56.7 per cent weight in curing and the ripe grass only 12.9 per cent. The extreme succulence of immature corn and other crops previous to the formation of seed, is a fact. which the dairyman who feeds soiling crops must consider if he would uniformly maintain a ration up to the desired standard. The proportion of water in plants is influenced also by the lack or excess of soil moisture. The soil and not the atmosphere is the source of supply of vegeta- tion water, which, taken up by the roots, traverses the plant and passes into the atmosphere through the leaves. If the supply is abundant, the tissues are constantly fully charged, but if, by reason of drought, the soil becomes very dry, the outgo of water by evap- oration may exceed the income. What farmer has not seen his corn with rolled leaves during an August drought ! The vegetation water had fallen below the 36 The Feeding of Animals normal, or below what was necessary to maintain the tissues in their usual condition of rigidity. This leads to the observation that the water in a growing plant is that which is in transit from the soil to the air. This liquid stream enters the plant with its load of building materials, takes into solution the compounds elaborated in the leaves and aids in trans- porting them to the points of rapid growth, finally passing into the air from the surface of the foliage. Throughout the entire growing season, the plant acts as a pump, drawing from below through the roots the water which it needs for various purposes, and dis- charging it into the air. It was found that in Wis- consin 309.8 tons of water was evaporated by the plant for each ton of dry matter in the crop. Four tons of dry matter per acre is not an unusual product with maize, requiring 1,239.2 tons, or 10.4 inches of water for its growth, the equivalent of about five -eigh- teenths of an average annual rainfall. This is a fact of great significance to the stock feeder. His success be- gins with proper husbanding of the plant -food resources of the farm, of which water is an important factor. Water in feeding stuffs. — Cattle foods, whether in the green or air -dry condition, always contain more or less water. The proportion is greatly variable, depend- ing upon several factors. With the green foods, the range of percentages is similar to that of the living plants previously noted. As, however, forage plants are used at varying lengths of time after cutting, and as a loss of moisture begins immediately after the plant is severed from its source of water supply, the amount of Water in Feeding Stuffs 37 dry matter in a green cattle food is somewhat uncer- tain, unless a water determination is made in the ma- terial exactly as it is fed. In all experimental work this precaution is necessary to accuracy. Roots and potatoes contain a large proportion of water, which, owing to their structure, is slowly evaporated. In a cool, moist cellar, their water content will remain prac- tically unchanged for a long time. In a warm, dry room evaporation occurs and they shrivel and lose weight. The water content of air -dry foods varies with the condition in which they were stored, the length of time after storage and the percentage of moisture in the air. Early cut hay often goes to the barn less perfectly cured than the late cut, and all hay dries out more than is generally realized during the first few months of storage. Concerning these points, the writer has ob- tained data through experiments at the Maine State and Pennsylvania State Colleges. Fourteen lots of hay, some early cut and some late cut, were weighed when stored and after remaining in the barn for several months. The results follow: Early cut Late cut As stored After several months Per cent loss As stored After several months Per cent loss Timothy, 1881.. . 3634 2307 36.5 4234 3390 19.9 << 1882.. . 3634 2556 29.7 3802 3168 16.7 tt 1881.. . 5000 3922 21.6 5270 4035 23. t< 1882.. . 3570 3037 14.9 4017 3413 15. Clover, 1882.. . 2110 1215 42.4 1520 1130 25.6 Timothy, 1888.. . 2815 2470 12.2 2790 2420 13.3 << Ave 1889.. . 5070 4225 16.6 6208 5086 18.1 General average loss, 22.2. 38 The Feeding of Animals It is probable that hay seldom loses less than one- eighth of its weight during storage, and often much more. As illustrating the variations in the proportions of water in hay due to changes iu air moisture, reference is made to observations by Professor Atwater. He found that dry hay hung in bags in a barn varied in water con- tent between 7.5 per cent and 13.6 per cent during the months of May, June and July. Hay in large masses would change less, but would be affected, doubtless, by long periods either of very dry weather or very wet. The proportion of moisture in coarse foods and grains has much to do with their preservation in a sound condition. New hay and grains when packed in large masses are subject to fermentations, which injure their quality and diminish their food value. This is due to the fact that sufficient moisture is present to allow the growth of low forms of life with certain at- tendant chemical changes. Feeding stuffs containing 20 per cent or more of water, — and this is likely to be the case with clover, rowen, field -cured cornf odder and stover, new oats and new corn, — when stored in large quantities are afmost certain to heat and become musty or moldy, always involving a loss of nutritive value, a result wholly due to the large proportion of water present. Water in the animal. — Water is an important and abundant constituent of animal organisms, from the lowest to the highest forms. The blood, which is from one -thirtieth to one -twentieth the weight of the bodies of farm animals, is at least four -fifths water, while the Water in Animals 39 soft tissues have been found to contain from 44 per cent to 75 per cent, according to the species and con- dition of the animal. The most extensive and com- plete analyses so far made of the entire bodies of animals were performed by Lawes and Gilbert at Roth- amsted, England. In this country four steers were analyzed at the Maine Experiment Station, and in the study of human nutrition problems many determi- nations of water have been made in the carcasses of bovines, swine, sheep, poultry and game. The figures are as follows: Water in entire body Per cent Ox, well-fed, Lawes & Gilbert 66.2 Ox, half fat, Lawes & Gilbert 59. Ox, fat, Lawes & Gilbert 49.5 Steer, 17 months old, medium fat, M. E. S 59. Steer, 17 months old, medium fat, M. E. S 56.3 Steer, 27 months old, fat, M. E. S 51.9 Steer, 27 months old, fat, M. E. S 52.2 Calf, fat, Lawes & Gilbert 64.6 Sheep, lean, Lawes & Gilbert 67.5 Sheep, well-fed, Lawes & Gilbert 63.2 Sheep, half fat, Lawes & Gilbert 58.9 Sheep, fat, Lawes &'_ Gilbert 50.9 Sheep, very fat, Lawes & Gilbert 43.3 Swine, well-fed, Lawes & Gilbert 57.9 Swine, fat, Lawes & Gilbert 43.9 Chicken, flesh 74.2 Fowl, flesh 65.2 Goose, flesh 42.3 Turkey, flesh 55.5 It is very evident that, in general, considerably more than half of the weight of the bodies of our domestic 40 The Feeding of Animals animals consists of water, the limits observed in all species and conditions here mentioned being 42.3 per cent and 67.5 per cent. The percentage of water varies with the species, age and condition. Swine carry a notably small proportion. The calf's body, even though fat, is comparatively watery. It is very noticeable that with oxen, sheep and swine the lean animals contain a much larger proportion of water than the fat. This does not mean that in the process of fattening the fat is substituted for water, and so expels it from the organism, but that the in- crease has a much smaller percentage of water than the body in its original lean condition. This is well illustrated by the data from two independent investi- gations at Rothamsted and at the Maine Experiment Station. The former investigation showed that when swine, sheep and oxen are fattened the increase con- tained from 20 per cent to 24 per cent of water, this being half the proportion found in the entire bodies of the lean animals. The Maine Station results established the fact that in the increase of two steers from the age of 17 months to 27 months, during which time a fat- tening ration was fed, there was 42 per cent of water, the bodies of the younger steers having 58.2 per cent. It is a common remark among unscientific people that beef from mature animals " spends " better than that from young, the same observation being made in com- paring lean and fat beef. Modern investigation shows clearly that the reason for this lies partly in the differ- ence in water content. Dry matter, and not water, is the measure of food value. The Ash Contents 41 ASH The ash or mineral part of plants or animals occu- pies a minor place in the discussions which pertain to the principles and problems of animal nutrition. Much is said and written about the carbon compounds of living organisms, but the compounds of the mineral world, in their relation to foods and to the processes of growth, are generally passed by with brief comment, much less than would be profitable. It is certainly desirable to gain a clear understanding of the combi- nations, distribution and functions of these bodies. Their importance as necessary constituents of foods and animals is no less than pertains to the carbon compounds, although their scientific and commercial prominence as related to animal nutrition is much less. As previously stated, the mineral portion of a plant or animal is measured by the ash or residue after com- bustion, the principal ingredients of which are the following : Acids Bases Hydrochloric acid HC1. Potash K 2 Sulfuric acid H 2 S0 4 Soda Na 2 Phosphoric acid H 6 P 2 8 Lime CaO Silicic acid Si0 2 Magnesia MgO Carbonic acid C0 2 Iron oxid Fe 2 3 Other mineral compounds are found in the various forms of vegetable life, but those mentioned are all that we need to discuss at length. The acids and bases do not exist in the ash as 42 The Feeding of Animals shown, but they are united to form salts, and so we have the chlorides, sulfates, phosphates, and carbon- ates of potassium, sodium, calcium and magnesium. These are nearly all familiar objects in common life, as, for instance, sodium chloride (common salt), potas- sium chloride (the muriate of potash of the market), potassium sulfate (the sulfate of potash of the market), calcium sulfate (of which gypsum or land plaster is composed), calcium phosphate (burned bone is chiefly this compound), potassium phosphate (a compound of phosphoric acid and potash found chiefly at the drug- gist's) and calcium carbonate (limestone). It should be remembered that the compounds in the ash are not necessarily those of the plant or animal. During the process of ignition, there is a rearrangement of the acids and bases, so that phosphoric acid which was combined with potash in the plant may be united with lime in the ash. Much of the lime in the ash is in union with carbonic acid, which in the plant may have been associated with vegetable acids, such as oxalic and tartaric, and part of the sulfur and phosphorus of the ash comes from the nitrogen com- pounds. These salts differ greatly in their properties. Some are soluble in water, others are not. To the former class belong all the chlorides, and the potassium and sodium sulfates and phosphates. The normal phos- phates of calcium and magnesium are insoluble in water, but soluble in various acids. These facts are important in showing what salts are in solution in the plant and animal juices, and what effect leaching with Ash in Plants 43 water or other solvents would have upon the inorganic portion of cattle foods. The mineral compounds of plants. — All plants and feeding stuffs contain mineral compounds, which are important in this connection because, excepting com- mon salt, they are the only source of the mineral con- stituents of the animal body. These are held in the plant tissue chiefly in three ways; in solution in the juices, in crystals in the cells and as incrustations in the cell walls. With the exception of oxygen, sulfur and phosphorus, no ingredient of the ash has sus- tained, so far as known, a structural relation to plant growth. When the fresh plant substance is reduced to an air- dry condition, the salts in solution become de- posited in the tissues as solids. The mineral matter of plants and feeding stuffs is by no means uniform in composition and quantity, even in the same species or class of materials, although in some grains there is a fair degree of similarity in this respect. Certain factors cause variations, such as species, stage of growth, fertility, the part of the plant, manner of curing or treatment of a feeding stuff and changes due to manufacturing processes, and the variations which exist pertain not only to the amount of ash but also to its composition. Variations due to species. — Different species of plants, and consequently different feeding stuffs, are greatly unlike in their content of mineral matter. The figures below illustrate this fact, further confirmation of which may be had by consulting the table in the appendix: 44 The Feeding of Animals No of Per cent analyses ash Mixed grasses 106 7. Timothy grass 9 6.8 English ray grass 11 12.1 Red clover, in bloom 113 6.9 White clover, in bloom 4 7.3 Seradella, in bloom 3 9.8 Buckwheat 17 8.2 Potatoes 59 3.8 Sugar beets 149 3.8 Mangel-wurzel 19 7.6 Turnips 32 8. Carrots 11 5.8 Winter wheat 110 2. Oats 57 3.1 Summer barley 57 2.6 Maize 15 1.4 Peas 40 2.7 Field beans 19 3.6 It is important to know that these variations pertain not alone to the quantity of ash but to the proportions of compounds which it contains : The mineral compounds ofp> lants and feeding stuffs (per cent in the dry matter) Pot- ash Soda Lime Mag- nesia Iron oxide Phos- phoric adid Sul- furic acid Silica Chlor- ine Mixed grasses.. ....1.86 .26 1.11 .48 .11 .50 .36 2. .43 ...2.37 .12 .55 .22 .06 .80 .19 2.19 .35 Redcloverin bloom2.21 .13 2.39 .75 .07 .66 .22 .18 .26 ....1.57 .53 2.21 .69 .15 .94 .54 .33 .31 Alfalfa ....1.74 .13 3. .36 .14 .63 .42 .70 .22 ...2.54 .19 3.32 1.09 .12 .50 .30 .09 .06 Roots ...2.27 .11 .10 .19 .04 .64 .25 .08 .13 ....2.03 .34 .23 .30 .04 .47 .16 .09 .18 ...3.96 1.23 .28 .83 .06 .65 .23 .15 .75 Turnips ....3.64 .79 .85 .30 .06 1.02 .90 .15 .41 ...2.02 1.16 .62 .24 .05 .70 .35 .13 .25 Ash in Plants 45 Phos- Sul- Pot- Mag- Iron phoric furic Chlor- Grain ash Soda Lime nesia oxide acid acid Silica ine Winter wheat 61 .04 .06 .24 .03 .93 .01 .04 Oats 56 .05 .11 .22 .04 .80 .06 1.22 .03 Summer barley 56 .06 .07 .23 .03 .92 .05 .68 .03 Maize kernel 43 .02 .03 .22 .01 .66 .01 .03 .01 Peas 1.18 .03 .13 .22 .02 .98 .09 .02 .04 Field beans 1.51 .04 .18 .26 .02 1.41 .12 .02 .06 We cannot fail to observe as we study these figures that potash, lime and phosphoric acid are the promi- nent mineral compounds of the whole plant, and con- sequently it is with them that we find the important variations. The true grasses differ from the clovers and related plants in containing much less lime and greatly more silica, the phosphoric acid and potash not being greatly unlike in the two cases. As a source of lime, then, the clover hay is superior. Potatoes and roots are richer in potash and poorer in lime than are the coarse fodders. The grains with hulls contain much silica, and those like wheat and corn but little. The seeds of the legumes are richer in potash and lime than those of the grasses. The maize kernel is especially poor in lime. The distribution of mineral compounds in the differ- ent parts of the plant. — Because the farmer separates his crops into grain and straw, and the manufacturer goes farther and divides the grain into parts, thus modifying the character of feeding stuffs, it is worth while to know just how the mineral compounds are distributed in the stalk, leaves and fruit, especially of the cereal grain plants. A comparison of the straws and grains shows striking dissimilarities: 46 The Feeding of Animals Per cent in ike dry matter Phos- Sul- Total Pot- Magne- Iron phoric furic Wheat ash ash Soda Lime sium oxide acid acid Straw 5.4 .73 .07 .31 .13 .03 .26 .13 Kernel 2. .61 .04 .06 .24 .03 .93 .01 Oats Straw 7.2 2.07 .24 .50 .26 .08 .33 .23 Kernel 3.1 .56 .05 .11 .22 .04 .80 .06 Maize Straw 5.3 1.93 .06 .58 .30 .12 .44 .28 Kernel 1.4 .43 .02 .03 .22 .01 .66 .01 Peas Straw 5.1 1.17 .21 1.89 .41 .09 .41 .32 Kernel 2.7 1.18 .03 .13 .22 .02 .98 .09 Silica ine 3.62 .09 .04 3.34 .31 1.22 .03 1.53 .07 .03 .01 .35 .29 .02 .04 In the first place, the straws contain more mineral matter than the grains. It is very evident also that in the straws there is much more potash, lime and silica than in the grains, while phosphoric acid in most cases exists in larger proportions in the latter. The roots and leaves of beets and turnips present a striking difference in mineral content: Per cent in the dry matter Phos- Sul- Total Pot- Mag- Iron phoric furic Chlor- Sugar beets ash ash Soda Lime nesia oxide acid acid Silica ine Roots 3.8 2.03 .34 .23 .30 .04 .47 .16 .09 .18 Leaves 14.8 3.90 2.05 3. 1.69 .08 .71 .79 1.51 1.26 Fodder beets Roots 7.6 3.96 1.23 .28 .83 .06 .65 .23 .15 .75 Leaves 15.3 4.71 2.98 1.63 1.46 .22 1. .86 .56 2.45 Turnips Roots 8.0 3.64 .79 .85 .30 .06 1.02 .90 .15 .41 Leaves 11.6 2.73 1.10 3.83 .46 .18 .85 1.09 .45 1.18 There appears to be a tendency for mineral com- pounds to accumulate in the leaves of plants, and leafy plants are, as a rule, those which appropriate these most freely. Ash in Feeds 47 The ash of the outside of the stem and of the husks of seeds is in relatively large proportions, due sometimes to an excess of silica. Husked rice kernels contain not over .5 per cent of ash, while the husks contain 39 per cent or over. Influence of manufacturing processes on the ash con- stituents. — The cattle food market is abundantly sup- plied with the residues from certain manufacturing in- dustries, such as milling, brewing and starch produc- tion. The most prominent waste product is wheat bran. As this is the outside of the kernel, we would naturally expect, in view of the previous statements, that it would be rich in mineral compounds, and we find such to be the case. The wheat kernel contains about 2 per cent of ash, wheat bran about 6 per cent and wheat flour about .5 per cent. Bran may become, therefore, an important source of mineral com- pounds in the ration. In brewing, the kernels of barley are subjected to a leaching process, which results in taking out the soluble mineral salts, chiefly the salts of the alkalies, potash and soda, leaving behind, in part, the compounds of lime and magnesia. This fact is made clear by comparing the analysis of the ash of barley with that of brewer's grain: Partial composition of ash (per Gent) Mag- Phos. Potash Soda Lime nesia acid Summer barley 56 .06 .07 .23 .92 Brewer's grains 15 . — .64 .45 1.69 As a source of phosphoric acid and lime the brew- er's grains are more efficient, pound for pound, than 48 The Feeding of Animals the original barley grains. Much the same thing oc- curs in the manufacture of starch and glucose from the maize kernel, as in brewing, for the ground grains are either treated with water or with dilute acid. As the salts in the maize kernel are largely those soluble in water, the gluten meals and feeds, which are the residues, have a very small proportion of ash, not over half that in the original kernel. Analyses show that the potash is practically all extracted, and that the phosphoric acid is materially diminished. The mineral compounds of animal bodies. — The min- eral compounds of animals are nearly similar in kind to those of plants, but are very different in relative pro- portions. This is made plain by a comparison of the figures given below: Ash in plants and animals (per cent) Pot- Mag- Phos. Sul. Dry substance Total ash Soda Lime nesia acid acid Timothy hay . . 6.8 2.4 .12 .55 .22 .80 .19 Maize kernel . . 1.4 .43 .02 .03 .22 .66 .01 Wheat kernel . . 2.0 .61 .04 .06 .24 .93 .01 Fresh bodies Fat ox 3.9 .14 .12 " 1.74 .05 1.56 Fat sheep 2.9 .14 .13 1.19 .04 1.13 Fat swine 1.8 .10 .07 .77 .03 .73 Potash is much less prominent in the composition of the animal than is the case with plants, and phos- phoric acid and lime are much more so. In general, more than 80 per cent of the ash of the animal body consists of phosphoric acid and lime in combina- tion as calcium phosphate, whereas these two com- pounds constitute less than one-fifth of the ash of Silicic acid Chlor ine 2.2 .03 .04 .35 .01 .01 .02 Ash in Animal Bodies 49 hay and less than one-half of the ash of maize and wheat kernels. The distribution of inorganic compounds in the animal body. — The bones contain a very large proportion of the ash constituents found in the animal body, the soft parts being poor in mineral salts. Usually the ash makes up between 60 and 70 per cent of bone, and the bony framework is from 6 to 9 per cent of the entire bodies of domestic animals. More than 80 per cent of the ash of bone is calcium phosphate, which is asso- ciated with calcium carbonate, calcium fluoride, calcium chloride and magnesium phosphate. The bones of all species of animals show a remark- able similarity of composition, the average of which would not be far from the following: In 100 parts of the ash of bone {average) Calcium phosphate 83. 9 Calcium carbonate 13. Calcium in other combinations 35 Fluorine 23 Chlorine 18 97.66 The muscular tissue and other soft parts of the animal body contain less than 1 per cent of incombustible bodies. The ash of flesh is mostly phosphoric acid and potash, accompanied by comparatively small amounts of soda, lime and magnesia and minute quantities of chlorine and iron. Unquestionably, potassium phos- phate is the predominating salt in flesh, as calcium phosphate is in bone. D 50 The Feeding of Animals The blood contains a variety of mineral substances, the chief of which is sodium chloride, or common salt, although a minute amount of iron is present, having a most important function. In the bile, soda is abundant, combined mostly with the peculiar or- ganic acids of this secretion. Chlorine is a constant constituent of the gastric juice, its presence as chlor- hydric acid being essential to digestion. The preceding are some of the prominent facts concerning the inor- ganic compounds of the animal body, but they are only a brief suggestion of the knowledge which pertains to this part of animal chemistry. CHAPTER V THE COMPOUNDS OF ANIMAL NUTRITION, CONTINUED — THE NITROGEN COMPOUNDS The nitrogen compounds of the vegetable and ani- mal kingdoms have received much attention from scien- tific investigators and writers during the past fifty years. It is quite the custom to declare that certain members of this class of substances are the ones most important in the domain of animal nutrition, and many writers give to protein so prominent a place in dis- cussing the relative value of feeding stuffs as to almost ignore the other nutrients. Certain investi- gators claim, on the other hand, that from the stand- point of results in practice the function and relative value of protein have been unduly magnified. What- ever may be the correct view concerning these antago- nistic opinions, it is very evident that the present tendency is towards a fuller discussion of the office and value of the non- nitrogenous bodies. There can scarcely be any disagreement, however, concerning the general proposition that protein plays a leading part in the processes and economy of animal nutrition. This is true for several reasons: (1) The nitrogen compounds are those fundamental to the energies of the living cells which make up the tis- (51) 52 The Feeding of Animals sues of plants and animals. The basic substance of the active cell is protoplasm, a complex nitrogenous body, which Huxley called "the physical basis of life." Around this primal substance seem to center all vital activities, especially the transformation of the raw materials of the inorganic world into the organized structures of life. (2) These compounds are structurally essential to the growth of living tissues and to the formation of milk. The significance of this fact is intensified by their paucity in many of the feeding stuffs that are ordinarily produced on the farm . (3) Nitrogen combinations suitable for use as plant and animal food have reached a position of great com- mercial importance. They are the most costly of all the plant -building materials, the significance of which is intensified by their scarcity in the soil in useful forms, and by their easy passage beyond reach either through chemical changes which liberate the nitrogen, or through leaching from the soil. Nitrogenous feed- ing stuffs also bear relatively high market prices. PROTEIN For the sake of brevity and convenience, the nitro- gen compounds of cattle foods, both vegetable and animal, are designated as a class by the single term protein. When, therefore, it is stated that a feeding stuff contains a certain percentage of protein, refer- ence is made to the total mass of nitrogen compounds present, which may be many in number and of greatly differing characteristics. Protein 53 It should be stated, by way of preliminary explana- tion, that, in the past, the proportion of protein (total nitrogen compounds) in a feeding stuff has been ascer- tained by determining the total amount of nitrogen and then multiplying its percentage number by the factor 6.25. This method is based on the assumption that the average percentage of nitrogen in protein com- pounds is sixteen, which is not true to so close a de- gree of approximation as was formerly believed to be the case. It may happen in some instances that a determination made in this way is sufficiently accurate, while in other cases the margin of error is large. Re- cent investigations with perfected methods show per- centages of nitrogen in the numerous single proteid substances found in the grains ranging from 15.25 to 18.78. These are largest in certain oil seeds and lu- pines and smallest in some of the winter grains. Ritt- hausen, a prominent German authority, concedes that the factor 6.25 should be discarded, and suggests the use of 5.7 for the majority of cereal grains and legu- minous seeds, 5.5 for the oil and lupine seeds, and 6.00 for barley, maize, buckwheat, soja bean, and white bean (Phaseolus), rape, and other brassicas. Nothing short of inability to secure greater accuracy justifies the longer continuance of a method of calculation which is apparently so greatly erroneous. As previously stated, protein is the accepted name for a class of compounds. Just how there came about such a grouping of a large number of substances under a single head it is not necessary to consider in this con- nection, but it should be made clear that the individual 54 The Feeding of Animals compounds which are included under this term are in part so unlike in chemical and physical properties as to warrant the assertion that they have nothing in com- mon except that they contain nitrogen; and we may believe that their unlikeness in composition is do greater than the differences in their nutritive fuuctions. It is very evident that it is not only convenient, but necessary, to classify such a heterogeneous group of bod- ies into subdivisions more nearly alike in their charac- teristics. When we come to consider doing this we discover a most unfortunate confusion of terms. Our leading chemists evidently have reached no agreement in this matter, and so we find almost as many ways of dividing the nitrogenous compounds of plant and ani- mal life as there are prominent writers. Nevertheless, some system of classification must be used in this connection, and perhaps none is more con- venient or logical than the one reported by a commit- tee on nomenclature, representing the Association of Agricultural Colleges and Experiment Stations. The classification given here is essentially this one, although there are included in it certain distinctions very clearly set forth by Professor Atwater in a paper associated with the above-mentioned report. In the arrangement adopted it is recognized that certain nitrogen bodies included under protein are so unlike the main and important members of this group as to be properly st}'led non-proteid. It is also con- ceded that there are simple or native proteids which seem to stand in the relation of "mother" substances to a large number of protein bodies that have been Protein — Proteids 55 modified either by various external agencies, or are the result of a union of proteids with compounds of another class. More than all, the classification here used seems to be fairly well adapted to the effort of making clear to the beginner or unscientific reader this most difficult division of our subject. No apology is offered for the hard names that are used. They are the only ones available, and as they have the merit of conciseness, it is hoped that in time they will come into an intelligent popular use. These are: /Albumins Globulins Albuminoids Protein. To- tal nitrogen compounds . ' Proteids (_ and allies Modified , f Derived \ Compound - Non-proteids Collagens or gelatinoids Extractives Amides, a m i d o , acids, etc. Other nitrogen compounds are included with the protein by the present methods of estimation, such as alkaloids and nitrates, but these are so uncommon in feeding stuffs, or are present in such small quantities, that they may be safely ignored. PROTEIN — THE PROTEIDS Proteids are the main and important nitrogen com- pounds either in the plant or in the animal. The pro- tein of seeds contains little else than proteids, while that of young fodder plants and especially of roots 56 The Feeding of Animals consists more largely of non-proteids. They are also the chief constituents of muscular tissue. The chemical constitution of the proteids is not definitely known. No investigator has yet been wise enough to search out their manner of combination, but it is generally con- sidered to be very complex. It is believed that a cer- tain one of these compounds holds in a single molecule no less than 5,000 atoms. These bodies are con- structed from the simpler ones of the inorganic world through the vital energies of plants, and they appar- ently must come to the animal fully organized. The ultimate composition of proteids, that is, the proportions of the elements which they contain, has been carefully studied, and while there are material differences among them in this respect, the limits of variation are not especially wide, as can be seen from the following figures taken from Neumeister: Elementary composition of the proteids Per cent Per cent Average Carbon 50. to 55. 52. Hydrogen 6.5 to 7.3 7. Nitrogen 15. to 17.6 16. Oxygen 19. to 24. 23. Sulphur 3 to 2.4 2. We see that the number of elements ordinarily found in the proteids is five, nitrogen and sulphur being those that chiefly distinguish these bodies from all others which make up the mass of combustible matter. Two other elements are occasionally involved, as, for instance, the phosphorus of casein and the iron of blood. Protein — Albuminoids 57 These proteids are familiar objects on the farm, and their properties are matters of common observation. .When the farmer's boy secures the tenacious cud of gum from the fresh wheat gluten, or when the house- wife watches the strings of coagulated albumin sepa- rate from the cold water extract of fresh lean beef that is brought to the boiling point, or observes the white of an egg harden into a tough, white mass as it is dropped into boiling water ; when we observe the stiffening of the muscular tissue of the slaughtered animal or the rapid formation of strings of fibrin in the cooling blood; — in all these instances there are manifested certain chemical or physical properties which pertain to these most important and useful com- pounds. The albuminoids. — Of all the nitrogen compounds, these exercise the most general and prominent func- tions in plant and animal life. They not only make up a large part of the protein of feeding stuffs, but their office in the nutrition of animals is definitely under- stood to be of the most important kind. As has been indicated, the albuminoids are regarded as divisible into groups, the individuals of each group having certain distinguishing common properties. The two subdivisions whose members are most common and widely distributed are the albumins and globulins. Among these and their derivatives and compounds we find albumin, myosin, fibrinogen, albuminates, pro- teoses, peptones, casein and nuclein, — a formidable lot of names whose use seems necessary to a statement of the facts we wish to discuss. It is hoped that the 58 The Feeding of Animals following explanations will clothe them with practical meaning. (1) The albumins. There are several albumins. They are found in the juice of plants, in certain liquids of the animal body such as the serous fluids, in muscle, blood and milk, and abundantly in eggs. Unlike other proteids, these compounds are soluble in pure cold water, and when such a solution is heated to the boil- ing point, they separate from the liquid by coagulation and become insoluble unless acted upon by some strong chemical. When macerated beef is treated with cold water the albumin in it goes into solution, and if this ex- tract is boiled to make beef tea, it is a matter of com- mon observation that the albumin separates in clotted masses. None remains in the tea. It is w T ell for the housewife to know that all lean meat contains this substance, which by prolonged treatment with cold water may be removed to the detriment of the residue, and which, if the exterior surface of the meat is brought in contact with boiling water at once, coagulates in the outer laj-ers of the meat and thus prevents an exten- sive loss of soluble matter. The clear serous fluid which is left after removing the clot from blood contains albumin which may also be coagulated by heat. After the casein is removed from milk by acid or rennet, the albumin of the milk remains in the whey. It is this which in part causes milk to clot if brought to the boiling point. One of the most familiar examples of this class of proteids is the white of an egg, which, when cooking in boiling water, be- Protein — A Tbuminoids 59 comes a hard, white, coagulated mass. Albumin in the serous fluids and in blood is called serum -albumin, in milk, lact- albumin and in eggs, ova-albumin. A small proportion of the proteids of plants is found to be albumin; for instance, Osborne found .6 per cent in wheat, .43 per cent in rye, .3 per cent in barley, .5 per cent in soja beans, and some in most seeds. This possesses essentially the same characters as the animal albumin described previously. Whenever a vegetable substance is leached with water, it is prob- ably this proteid which would be the first to suffer removal or destructive fermentation. (2) The globulins. It is fully recognized that when plant and animal tissues are treated with water but a small part of the proteids dissolve. If, however, we add to the water a mineral salt, especially common salt (sodium chloride), sufficient to secure a 10 per cent solution, an additional and considerable amount of al- buminoids is extracted. These compounds are called globulins and differ from the albumins in being insolu- ble in pure water and in a saturated solution of certain mineral salts, such as sodium chloride. The globulins form an important part of the proteid content of plants and of animal tissues, both in quantity and in having a maximum nutritive usefulness. In plants these proteids seem to be especially abun- dant and widespread. Our best and most recent knowl- edge on this point comes from investigations conducted in the laboratory of the Connecticut Agricultural Ex- periment Station, chiefly by Osborne. In these re- searches the seeds of fifteen species of agricultural 60 The Feeding of Animals plants were studied, all of which were found to contain globulins. In some the proteids consisted largely of these compounds. The percentage content in certain seeds was determined approximately: Globulins in certain seeds Per cent Per cent Kidney bean 20. Maize 0.4 Cottonseed meal 15.8 Lentil 13. Peas. 10. Horse bean 17. Lupin 26.2 Soy bean Chiefly globulin The seeds of the legumes, as a rule, have the largest proportion of these albuminoids. From present knowledge, many seeds appear to have characteristic globulins which are unlike in their chem- ical properties. These have been given names derived from the general names of the species in which they are found. Thus we have amandin in almonds, ave- nalin in oats, corylin in walnuts, phaseolin in several species of beans, glycin in the soy bean, maysin in maize, vicilin in horse beans, vignin in the cow-pea, hordein in barley, and tuberin in the potato. One globulin called edestin appears to be quite generally distributed in the seeds of agricultural plants, having: been found in a larger number than any other proteid yet discovered, including all the cereals, castor bean, cottonseed, flaxseed, hemp, squash and sunflower, though it is not abundant in any one of these. The animal globulins of which we have definite knowledge are those that exist in the muscle and in the blood. The names which some of them bear are myosin, fibrinogen, paraglobulin, and, according to Protein — Albuminoids 61 some authors, vitellin. If finely divided, well- washed muscle (lean meat) is treated with a 10 per cent salt solution, first by rubbing it in a mortar with fine salt, and then adding enough water to secure the proper strength of solution, a globulin is dissolved to which the name myosin has been given. The view has been generally accepted that this compound does not exist as such in living muscle, but forms there by coagula- tion upon the death of the animal. This change has been looked upon as similar to the coagulation of blood through the formation of fibrin, and is regarded as the explanation of the stiffening of dead muscles (rigor mortis). The theory is held that a "mother" substance exists in the living muscle from which myosin is formed in much the same way as fibrin is developed in clotting blood from a preexisting body, but no single view as to exactly what occurs is fully accepted. There is, never- theless, a general agreement that rigor mortis is due to a clotting of the muscle, accompanied by marked chemical transformations, one final product being my- osin. The theory is advanced that ferments are present in the muscle, to the influence of which these changes are due, and without which they do not occur, but proof of this view is still lacking. In this whole field much is yet to be learned. Certainly, the chemistry of living and dead muscle is most profound, and offers to the bio-chemist a wonderfully attractive and fruitful field of research. Another prominent and remarkable globulin is the fibrinogen, which is found in the blood. It is common knowledge that when blood is drawn from the veins 62 The Feeding of Animals and cools it clots, a phenomenon which is nothing more than the formation of strings of fibrin. Fibrin as such is not found in living blood, but is one of the prod- ucts into which fibrinogen splits when exposed blood cools, probably because of the influence of a ferment. Stranger than all is the fact that so long as the blood is retained in the arteries and veins, even if the animal dies and grows cold, this clotting does not appear. Serum globulin is a collective name for several glob- ulins, which exist in blood serum and in the other fluids of the animal body, such as lymph and its allies, in- cluding those exudations which pertain to diseased conditions, especially dropsical. One more proteid has been generally classified as a globulin, although differing in some respects from the other members of this class. Reference is made to vitellin, which is the principal proteid in- the yolk of eggs. It is there intimately mixed with certain pecu- liar phosphorized bodies, which we shall notice later. The modified albuminoids. — All of the proteids pre- viously noticed may properly be called simple, native proteids. This characterization is appropriate because these are the bodies that possess the typical reactions and qualities of the albuminoids as a class, and are the principal ones found in the normal tissues of plants and animals. They are the basal substances from which others appear to be derived after modifications of one kind or another. It seems proper, therefore, to speak of certain other proteids as modified albuminoids, because, through various influences, either natural or artificial, they have acquired chemical and physical Protein — Modified Albuminoids 63 properties unlike those possessed by the mother sub- stances. A convenient division of these modified bodies, though perhaps not strictly scientific, may be made in accordance with the cause or manner of change. These causes are: (1) coagulating ferments; (2) heat; (3) aetion of acids and alkalies; (4) the ferments of digestion; (5) combinations with other compounds. (1) Coagulating ferments. Reference has been made to that interesting phenomenon, the coagula- tion or clotting of blood. As stated, this is now known to be due to a formation of a new compound, called fibrin. The mother substance, fibrinogen, and not the fibrin exists in the living blood, and it seems to be well proven that the splitting of the fibrin- ogen into two substances, one of which is fibrin, is due to the action of a ferment, designated as a fibrin ferment. It would be out of place to review the data upon which this conclusion is based. There are, to be sure, conflicting views, but the one stated seems to be the most fully established. Fibrin, after thorough washing, is an elastic white substance, which, in its chemical properties, stands very close to the albumins that are coagulated by heat. It has been held by various investigators that other changes in animal fluids and tissues are brought about in the same manner as the formation of fibrin, i. e., by the action of a ferment. In one case, this is certainly true, viz.; the curdling of milk under the influence of the ferment rennin. This ferment, which for cheese- making purposes is extracted from the fourth stomach 64 The Feeding of Animals of a calf, will, when added to milk at a proper tem- perature, cause the coagulation which gives us the cheese curd. The probable correct explanation of this familiar phenomenon is that the casein is decomposed into two other substances, one being paracasein and the other an albumin, the first of which subsequently unites with lime salts in the milk and forms the in- soluble substance that we know as curd. The occur- rence of this latter step appears to be proven by the fact that in the absence of lime salts no curd forms, but it immediately appears when such salts are added to the lime -free solution. As milk always contains sufficient lime to make coagulation possible, this ex- planation of the coagulation of casein has chiefly a scientific interest. Mention has been made of the clotting of dead muscle, or rigor mortis. As stated, certain investi- gators have suggested that the formation of the muscle clot is a process analogous to the coagulation of blood, and is brought about by ferment action. This view is not yet proven and must at present be considered as only hypothetical. If, however, it is found to be cor- rect, myosin would properly be classed as a derived albuminoid, its progenitor being the native proteid. (2) Heat. The effect of a boiling temperature upon the albumins has already been described. They are coagulated into a mass no longer soluble in water and only redissolved by treatment which changes their chemical constitution. The same thing happens to nearly all the globulins, and as with the albumins, this begins at varying temperatures. These coagu- Protein — Modified Albuminoids 65 lated bodies, which are typified by the white of an egg after contact with boiling water, are materially unlike the original compounds, though the nature of the modi- fication is not understood. We know them simply as coagulated albumins and globulins. (3) Action of acids and alkalies. When albumins and globulins are treated with dilute mineral acid, such as hydrochloric, they dissolve, through their .conversion, into acid albuminates. The action of dilute alkalies is similar, only that alkali -albuminates are formed. An- other effect of dilute acids upon proteids is to cause them to take up water, or suffer hydrolysis. These hydrolyzed bodies are called proteoses as a general name. This term signifies that they are derived from proteids. More fully specialized names are albumose, from albumin; globulose, from globulin; caseose, from casein, and so on. The important property which the proteoses takes on is their greater solubility as com- pared with the original compounds. This change has an intimate relation to digestive processes, or to the transference of the insoluble albuminoids of the food into the blood circulation, because in the stomach the hydrochloric acid of the gastric juice plays somewhat the same part as in dilute artificial solutions in render- ing the proteids soluble. (4) Ferments of digestion. When we come to a discussion of the processes of digestion we shall learn that nearly every digestive fluid contains one or more ferments, whose office appears to be to cause certain necessary modifications of the food proteids. The gen- eral effect of these ferments is to induce these proteids E 66 The Feeding of Animals to take up water, which transforms them to proteoses, and finally to peptones, the latter being so soluble as to pass through the walls of the alimentary canal into the blood. These proteoses are similar to those formed by the action of dilute acids, and in digestion may be considered as products intermediary between the original food proteids and the peptones which are the final result of albuminoid digestion. The acid of the stomach and the alkaline compounds in certain intesti- nal juices cooperate -in bringing about these necessary changes, for we know that in their absence the digestive ferments have no extensive action such as that de- scribed. Proteoses, i. e., albumoses, globuloses, case- oses, and the like, are soluble in water, are not coagu- lated by boiling their solutions, and in other ways are unlike the proteids from which they are derived. They are regarded, however, as not having lost their albu- minoid character, and, as will be shown later, they are re-formed by the metabolic energy of the animal into bodies similar to those from which they take their rise*. (5) Combinations. There are many nitrogenous compounds found in plants and animals which it is not possible to classify at present in any exact manner. They are undoubtedly derived from simple proteids, as those to which reference is made consist of albuminoids united to a body of a different kind. There are, first of all, certain bodies designated as nucleo- albumins, this name signifying that albumin is united to a nuclein, which, in its turn, is a combination of an albumin with phosphoric acid. The best known nucleo -albumin in agriculture is the casein of milk. Protein — Modified Albuminoids 67 Some of the properties of this body have been noticed in discussing the action of ferments. It has others which it is well to mention. In the first place, casein is not soluble in water. It is not in solution as it ex- ists in milk, but is regarded as being in a swollen con- dition. Again, it does not coagulate when milk is boiled. While the skin which forms on the surface of milk at a boiling temperature contains casein as one component, the only genuine coagulation that oc- curs is of the albumin present. Every housewife has noticed that when vinegar is added to milk in a small quantity the milk curdles. This is because the casein is modified by a weakly acid medium. A generous quantity of common salt, or of certain other salts, would have a similar effect. The nuclein, which forms a part of casein, can be split into an albumin and phosphoric acid, and is an illustration of a class of compounds which are gen- erally distributed in plant and animal tissue. The name is suggestive of the fact that these bodies exist in the nuclei of living cells, having an intimate relation to the protoplasm. Nucleins are also found in milk and eggs, and it appears quite possible that they take a pecu- liarly important place in nutrition, especially with young animals and milch cows. Another compound widely distributed in the animal kingdom is mucin, a prominent constituent of the slimy secretions of the mucous membranes that line the passages of the animal body, such as the throat and the intestines. This substance appears somewhat anomalous in being a combination of a proteid and a 68 The Feeding of Animals carbohydrate (animal gum). The fact of such a union is demonstrated by boiling mucin with an acid when an acid albuminate and carbohydrate -like body are produced. The mucin-like bodies are not especially important in nutrition. The blood contains a modified proteid which has an importance second to none in its relation to the nu- tritive processes. Reference is made to haemoglobin, which arises from the union of an albumin called globin and a coloring matter (pigment) called haema- tin. The latter is peculiar in containing iron. The especial function of haemoglobin is as a carrier of oxy- gen, and it is enabled to do its work through the property of taking in and releasing oxygen with great readiness. This action will be discussed later when we consider respiration. The gelatinoids. — It is a matter of common obser- vation in cookery that when meat containing tendons (cartilage) or bones is submitted to the action of boiling water there is obtained in the extract a sub- stance, which, especially when it is cold, we recognize as the one known as gelatine. Gelatine as such is not found in the animal tissues, but is derived from certain constituents of the connective tissues like the collagen of tendons and of bones, that from the latter source being also known as ossein. Collagen is undoubt- edly transformed into gelatine by taking up water. Gelatine is insoluble in cold water, but dissolves in hot. As the dry commercial article, it is a tena- cious substance which, when prepared in thin layers, is transparent. When collagen is acted upon by tan- Protein — Non - Proteids 69 nic acid, as for instance, when the skin of an animal is treated with an extract of hemlock or oak bark, the result is a substance which does not putrefy, and which gives to a tanned hide the properties of leather. Keratin and similar substances . — The hair, wool, hoofs, horns, and feathers are made up chiefly of a compound which bears the name keratin. Chemi- cally, it is closely related to the true proteids, we may believe, because when treated with heat or with chemi- cals like acids and alkalies, the resulting products are nearly similar to those that are secured in the same ways from albumins. Sulphur is a much more promi- nent constituent of keratin than of the native pro- teids, the analyses of human hair showing as high as 5 per cent, the average amount found in horn being 3.30 per cent. These keratin bodies belong usually to the epidermis or outer skin of the animal, and are modifications of the exterior tissue to serve certain distinct purposes where rigidity or wearing quality is necessary. PROTEIN — THE NON - PROTEIDS There are certain nitrogen compounds included in the term protein which are non-proteid in character, that is, they possess physical and chemical properties greatly removed from those which characterize albumin and other true proteids. Their office as nutrients is also less comprehensive than that of the albuminoids. One group of non -proteids which we speak of under the general term amides, is found chiefly in plants. 70 The Feeding of Animals They are soluble in water, and consequently are diffu- sible throughout the plant tissues. It is believed that they are the forms in which the nitrogen compounds of the plant are transferred from one part to another, as, for instance, from the stem to the seed. It has generally been held that amides are more abundant in young plants than in mature. A larger part of the nitrogen of roots and tubers is found in these com- pounds than in other feeding stuffs, the proportion in grains being the least, and is very small indeed. Such investigations as have been conducted point to the conclusion that amides are not muscle -formers, as is the case with proteids. This is a reason for regarding the protein of coarse foods, roots, and tubers, as of less value than that of the grains and grain products. The extractives are bodies found in the extract ob- tained from beef with cold water. After the albumin has been removed from such an extract by boiling, these compounds known as creatin and creatinin chiefly constitute the nitrogenous solids that remain. Their food value is small if anything, for they appear to pass through the body without change. CHAPTER VI THE COMPOUNDS OF ANIMAL NUTRITION, CONCLUDED — THE NITROGEN- FREE COMPOUNDS Much the larger proportion of dry cattle foods consists of non- nitrogenous material. This is espe- cially true of hays and cereal grains, consequently we find that from 75 to 80 per cent of the dry matter stored in a farmer's haymows and grain -bins is made up of substances of this class. While these com- pounds are not regarded by many as fundamentally so important as the nitrogenous, in quantity they un- questionably occupy the first rank. The activities of plant life are largely devoted to their production, and their use by animal life is correspondingly extensive. They may properly be called the main fuel supply of the animal world. Other nutrients aid in maintaining muscular force and animal heat, to be sure, but these compounds are the principal storehouse of that sun- derived energy which furnishes the motive power ex- hibited in all animal life. They are also important building materials, for they fill a necessary office of this kind in the formation of milk and in the growth and fattening of animals. The compounds of this class contain only three ele- ments, — carbon, hydrogen and oxygen. They may (71) 72 The Feeding of Animals be derived, therefore, wholly from air and water, and they constitute that portion of our cattle foods which is drawn from never -failing and costless sources of supply. The elementary composition of typical nitrogen - free bodies is given in this connection: Cellulose Starch Glucose Saccharose Stearin Olean Carbon 44.4 44.4 40. 42.1 76.7 77.4 Hydrogen.. 6.2 6.2 6.7 6.4 12.4 11.8 Oxygen 49.4 49.4 53.3 51.5 11. 10.8 The non- nitrogenous compounds of feeding stuffs are usually divided into three main classes, viz.; crude fiber, nitrogen -free extract and fats or oils. The sec- ond class is sometimes spoken of as carbohydrates, because it includes the carbohydrates as its principal members, and the third is known by the chemist as ether -extract, because ether is used to extract the fats or oils from the vegetable substances in which they are contained. The actual fat obtained from hay and other feeding stuffs is always less, however, than the ether -extract. CRUDE FIBER This is the tough or woody portion of plants. It consists largely of cellulose, a familiar example of which in a nearly pure form is the cotton fiber used in making cloth. Crude fiber is separated from asso- ciated compounds by the successive treatment of vege- table substance with weak acids and alkalies, and as so determined is sometimes improperly taken to represent Crude Fiber in the Plant 73 the amount of cellulose in a plant. While crude fiber is mainly cellulose, it contains a small proportion of other compounds, and besides, more or less cellulose is dissolved by the acid and alkali treatment, so that the percentages of crude fiber given in fodder tables only approximately measure the cellulose present in feeding stuffs. All plant tissue is made up of cells, the walls of which are chiefly or wholly cellulose. It is this sub- stance out of which is built the framework of the plant, and which gives toughness and rigidity to certain of its parts. The more of this a feeding stuff contains, the more tenacious it is, other things being equal, and the more difficult of mastication. The proportion of crude fiber in plants varies greatly with the species. Large plants have more than small ones, as a rule. The dry matter in the trunks and limbs of trees is mostly woody fiber, and the chemical treatment involved in making paper from wood has for its main object the separation of this from other sub- stances. Grass and other small herbage plants are less rich in fiber, still less existing in such species as pota- toes, turnips and beets. The proportions of cellulose in the different parts of a plant are greatly unlike. It is usually most abundant in the stem, with less in the foliage and least in the fruit. With vegetables like potatoes and turnips, the leaves are much richer in fiber than the tubers or roots, which contain a comparatively small proportion. Of the grains or seeds considerable is present in the outer coat- ings, while but little is found in the interior. Cousid- 74 The Feeding of Animals ering feeding stuffs as a whole, we find that hays, and especially straws, are rich in crude fiber, while tubers, roots and the grains contain only small amounts. In certain by-product grain foods, like bran, which is made up mostly of the seed -coatings, fiber is present in fairly large proportions, while in other materials like gluten meal, which are derived from the inner parts of the grain, the percentages are very small. The stage of growth at which a plant is used for fodder purposes has a marked influence upon the pro- portion of crude fiber. In young, actively growing vege- table tissue, the cell -walls are thin, but as the plant in- creases in age, these thicken, chiefly through the depo- sition of cellulose. Pasture grass has less cellulose than hay, and early cut grass less than that which is ripe. In general, the toughness and hardness of mature plants, as compared with young, is due to the increased pro- portion of woody fiber, although the decrease in the relative amount of water in the tissues and the deposi- tion of other substances have more or less effect. NITROGEN -FREE EXTRACT This name, like protein, is a collective term, being used to designate a group of compounds possessing certain characteristics in common. A great variety of substances are included under this head, many of which are among the most familiar objects of every -day life. Here we find the starches, sugars, gums and vegetable acids, compounds universally used, and which even chil- dren recognize by name. Certain of these non-nitrog- Nitrogen -free Extract — Carbohydrates 75 enous bodies of less importance are not so well known, as, for instance, such uncommon sugars as mannose and galactose, and their mother substances, mannan and galactan. The manufacture of beers and liquors and many of the ordinary phenomena of cooking operations, are based upon the chemical properties of the starches and sugars. To the presence of these and related bodies is due many of the agreeable flavors and appetizing characteristics of certain foods, as, for instance, the sweetness or acidity of fruits, and flavors produced in grain foods under the influence of heat. The most prominent and important members of the nitrogen -free extract group are known as carbohy- drates, the significance of this term being that these compounds contain carbon united with hydrogen and oxygen in the proportions in which these two elements exist in water. A common and convenient classification of the car- bohydrates, though not strictly rational from the stand- point of chemical constitution, is the following: 1. The starches, such as corn and potato starch and those bodies similar in elementary composition, including cel- lulose, inulin, glycogen, the dextrins, pectin and the gums. 2. The sugars, of which there are two main classes, the glucoses and the sucroses, the main sugar of "corn syrup" being a familiar example of the former class, and the ordinary crystallized sugar of commerce the most prominent member of the latter. The starches. — Starch is a widely distributed and abundant constituent of vegetable tissue. Food plants, 76 The Feeding of Animals especially those most used by the human family, con- tain it in generous proportions, in some seeds as much as 60 or 70 per cent being present. Probably only water and cellulose are more abundant in the vegetable world. Starch does not exist in solution in the sap, but is found in the interior of plant cells in the form of minute grains, which have a shape, size and structure characteristic of the seed in which they are found. Potato starch grains are large, about Tihr of an iuch in diameter, and are kidney- shaped, while those of the wheat are smaller, about ToVo of an inch in diameter, and resemble in outline a thick burning-glass. Corn- starch grains are angular, being somewhat six-sided, and those of other seeds show marked and specific characteristics. These differences in size and shape furnish the most important means of detecting adul- terations of one ground grain with another, as, for instance, when corn flour is mixed with wheat flour, a practice not unknown at the present time. Unless modified by some chemical change, starch is not dissolved by water. The starch grams are not affected by cold water, and in hot water at first only swell and burst. Prolonged treatment with hot water causes chemical changes to more soluble substances. For this reason the simple leaching of a fodder mate- rial removes no starch; at least not until fermentation occurs. At the same time the treatment of a ground grain with hot water so breaks up the starch grains that they are probably acted upon more promptly by ferments and digestive fluids, though perhaps no more fully, than when not treated. Nitrogen -free Extract — Starches 77 It is somewhat customary to refer in a popular way to the nitrogen -free extract of feeding stuffs as synony- mous with starch and sugar. Such a comparison con- veys an erroneous impression. The nitrogen - free extracts of many feeding stuffs, notably the straws and hays, contain at best a very small proportion of these carbohydrates, the amount of starch often being inappreciable. It is doubtful whether these coarse fodders usually contain enough to be chemically de- termined. This has certainly been found to be true in some cases. On the other hand, the dry matter of many seeds, such as rice and the cereal .grains, wheat, maize, barley or oats, is largely made up of starch. The same is true of potatoes and other tubers. John- son quotes the following figures from Dragendorff: Amount of starch in plants Per cent Per cent Wheat kernel.'. 68.5 Peas 39.2 Rye kernel 67. Beans 39.6 Oat kernel 52.9 Flaxseed 28.4 Barley kernel 65. Potato tubers 62.5 It appears that in grain plants starch forms most abundantly during the later development of the seed. At the Maine station none could be found in very im- mature field corn cut August 15, while on September 21 the dry matter of the whole plant on which the ker- nels had matured to the hardening stage contained 15.4 per cent. In general, the stem and leaves of for- age plants are poor in starch. The distribution of starch in seeds is worthy of note. The grain of wheat has been carefully studied 78 The Feeding of Animals in this particular, and it is found that this body does not normally exist in the seed -coatings, this tissue con- sisting largely of mineral matters, proteids, cellulose, and gums. On the contrary, the germ and the interior material deposited around it are rich in starch. To be sure, wheat bran, which is now very largely the outer seed -coats of the grain, has more or less, but this is due to imperfect milling. It is very evident, there- fore, that the term nitrogen -free extract, as applied to different cattle foods, stands for greatly unlike mix- tures of compounds, for we have largely starch in the cereal grains and mostly other substances in the straws and other coarse fodders. The importance of this fact will appear in considering the digestion and value of food compounds. Starch is an important commercial article, and for this purpose is mainly obtained from corn' and pota- toes. It is used as human food, as a source of dextrin and in other ways. By treatment with an acid, corn- starch is converted into the glucose of our markets. The vegetable gums. — It has become evident, doubt- less, during our discussion of nitrogen -free extract, that a considerable portion of this class of compounds consists of something else than the carbohydrates al- ready noticed. For example, at the Maine Experiment Station, the composition of several samples of corn fodder was closely investigated. It was found that the proportions of starch and sugar varied greatly, mostly in accordance with the stage of growth, being much more abundant in the mature plant. Even with flint corn nearly ripe, not over one -half of the Nitrogen- free Extract — Vegetable Gums 79 nitrogen -free extract of the entire plant was found to be starch and sugars. The other half evidently con- sisted of bodies either not so well known or not known at all. Among the less familiar compounds which we now recognize as existing quite abundantly in the stem and leaves of many, if not all, fodder plants are the vege- table gums, some of which are designated by the chemist as pentosans. Only a few such substances are definitely known, one of which, araban, is con- tained in gum arabic, gum tragacanth, cherry gum, beet pulp, and doubtless in various other materials; another being zylan or wood gum, which may be sep- arated in abundance from wood and straw. Stone has examined a large number of agricultural products for these gums, and if present methods of analysis are accurate, he found in the dry matter of such feeding stuffs as hays from several species of grass, corn fod- der, sugar beets, rutabagas, wheat -bran and middlings and gluten meal from 6 to over 16 per cent, the high- est proportions appearing in timothy hay, corn fod- der, and wheat -bran. In mature field -corn fodder he obtained about 16 per cent, thus accounting for about half of the nitrogen -free extract left after sub- tracting the starch and sugars. Wheat bran contained much more than middlings, and the least was present in gluten meal. These gums are surely much more abundant in the coarse foods than in the grains, a fact which, as we shall learn, is important in com- paring the nutritive value of different classes of feed- ing stuffs. 80 The Feeding of Animals The pectin bodies. — Another class of compounds much like the gums, and perhaps related to them chemically, is the pectin bodies. Some of these sub- stances are gelatinous in appearance. The jellying of fruits, such as apples and currants, is made possible by 4;heir presence. They exist in greater abundance in unripe fruit than in the ripe, consequently the former is selected for jelly-making. When such fruits are cooked, the pectin which they contain takes up water chemically and is transformed into a gelatinous sub- stance, and the secret of jelly-making is in stopping the cooking process before the chemical transforma- tions have passed beyond a certain point. Mucilages not greatly unlike the gums and pectins exist in cer- tain seeds and roots, the most notable instance being flaxseed. The sugars. — When considered from the stand- point of efficiency, the sugars are the most valuable of all the carbohydrates, although in quantity they are much less important than the starches, because they are found only in small amounts in the hays and to a scarcely appreciable extent in the ^grains. Certain dis- tinctively sugar plants, to be mentioned later, are ^wd agriculturally, which are sometimes used as cattle foods. Unlike starch, the sugars are found in solution in the sap of growing plants. It is probable that these are the forms in which carbohydrate material is trans- ferred from one part of the plant to another. It is easy to see that some such medium of exchange is necessary. The actual production of new vegetable Nitrogen- free Extract — Sugars 81 substance takes place in the leaves. When, therefore, cell -walls and starch -grains are to be constructed, in the stem and fruit, the building material must be car- ried from the leaves to these parts in forms which will readily pass through intervening membranes. Except- ing certain soluble compounds, closely related to starch, the sugars appear to be the only available bodies fitted for this office. It is very seldom that a plant contains only a single sugar. Generally two or more sugars are found to- gether. This is especially the case in the corn plant, sorghum and the juicy fruits, and the proportions of each depend somewhat upon the stage of growth of the plant. The most important sugar, commercially considered, is saccharose, which is the ordinary crystallized product of the markets. As a human food it is widely used, and is especially valuable ; and its manufacture and sale con- stitute a prominent industry. This sugar is obtained mostly from two plants, sugar cane and the sugar beet. It also exists abundantly in sorghum and in considerable proportions in ordifkfy field corn. The first spring flow of sap in one species of maple tree is richly charged with it, and in a few states large quantities of maple syrup and sugar are manufactured. Saccharose is not a prominent constituent of the more common cattle foods. While it occurs in meadow grasses, in sweet potatoes and in roots, and perhaps in minute proportions in certain seeds, it is onl3 r when the fresh corn plant, sorghum and sugar beets are fed that it constitutes a material part of the ration. In corn 82 The Feeding of Animals stover and in silage there is practically none, it having been destroyed by the fermentations that have taken place. The fruits generally contain saccharose, mixed with other sugars and organic acids, and upon the relative proportions of these compounds depends the character of the fruit as to acidity or sweetness. A sugar that is intimately related to the first growth which occurs in the germination of seeds is maltose, for it stands as an intermediate product between the store of starch in the seed and the new tissues of the sprout. The solution that the brewer extracts from the malted grains contains this compound as the prin- cipal ingredient, and through succeeding fermentations in the beer vats it is broken up into alcohol and other compounds. It sustains an important relation, there- fore, to the production of beers and other alcoholic liquors. The glucose syrups found in the markets some- times contain small quantities of this sugar. It is also found abundantly in the intestinal canal during the di- gestion of food, being derived from starch and other car- bohydrates. Maltose is similar to cane sugar in ultimate composition but not in constitution, though as a nutrient it evidently has an equivalent value. So far as known, however, it does not appear to occur in material quan- tities in feeding stuffs. Another important sugar is dextrose or grape sugar, or what is known in the markets as glucose. Excepting in the hands of the chemist it is seldom seen as crystals, although these appear in the "candying" of honey and of raisins. Its commercial forms are molasses and the Nitrogen -free Extract — Acids 83 syrups. Dextrose is found in practically the same plants that contain saccharose, such as sorghum, maize and the fruits. So far as known, it is always associated with some other sugar. On account of its difficult crystalli- zation and a lower degree of sweetness, it is less valuable for commercial purposes than cane sugar. That which appears in the market is largely made from starch by the use of an acid, and it is often utilized in adulterating the more costly saccharose. Many seem to regard glu- cose as a substance deleterious to health, but in consid- eration of the fact that in digestion, starch and most other sugars are reduced to this compound before en- tering the circulation of the animal, this view does not seem to be sustained. In fact, there is a lack of evi- dence to show the ill effect of glucose either upon man or animals. Still another sugar is levulose or fruit sugar, the composition of which is identical with dextrose but w r hich has a different chemical constitution. It accompanies dextrose and is found in some fruits in considerable quantities. It is as sweet as cane sugar, but does not form crystals with the same readiness. The acids. — Other substances besides those of a car- bohydrate character are included in the nitrogen -free extract. Chief among these are the organic acids, com- pounds which are found mostly in the fruits, although they appear in certain fermented products, such as silage and sour milk. The most important and well-known of these are acetic acid, found in silage and vinegar, citric acid in lemons, lactic acid in sour milk and silage, malic acid in many fruits, such as currants and apples, and 84 The Feeding of Animals , oxalic acid in rhubarb. Sometimes these acids are free, that is, not combined with any other compound, and sometimes they are united with lime or some other base, forming a salt. Excepting the fruits, only fermented feeding stuffs contain acids to an appreciable extent. When milk sours, the sugar in it is changed to lactic acid under the influence of a ferment. In silage, various acids develop, the main one being lactic, accompanied by acetic and other acids in much smaller proportions. These are formed chiefly at the expense of the sugars that enter the silo in the corn or other material which is subjected to fermentation. ANIMAL CARBOHYDRATES A study of the composition of the animal body teaches us that, unlike plants, it is very poor in carbo- hydrate compounds. Only two carbohydrates are of distinctively animal origin, viz; glycogen or animal starch, and milk sugar. Glycogen is closely related to starch, having the same percentage composition. It is a white powder, soluble in water, and may be extracted in very small amounts from the muscles and liver, the latter being the place where it is produced. As we shall see later, it seems to perform a very important office in nourishing the animal body. It was formerly believed that another carbohy- drate exists in muscle called inosite, but it is now known that this substance belongs to a different class of com- pounds. The only sugar of animal origin which is abundant Nitrogen- free Extract — Carbohydrates 85 in farm life is that found in milk and which is known in commerce as milk sugar or lactose. The milk of all mammals contains sugar, which appears to be the same compound with every species so far investigated. When fed wholly from the mother, this is the only carbohydrate which young mammals receive in their food. The aver- age proportion of sugar in the milk of domestic animals varies from three to six parts in a hundred, cow's milk containing about five parts. When the cream is removed much the larger part of sugar remains in the skimmed milk, and in cheese- making it is nearly all found in the whey, from which the milk sugar of commerce is ob- tained. Very soon after milk is drawn, unless it is heated to the point of sterilization, or is treated with some antiseptic, the lactose begins to diminish in quan- tity, being converted into lactic acid through the action of germ life. Sour milk, therefore, is different from sweet in at least one compound, and this change causes at least a slight modification of food value. CHEMICAL RELATIONS AND CHARACTERISTICS OF THE CARBOHYDRATES The various carbohydrates, which have been pre- viously described, are greatly unlike in appearance, taste and other physical qualities, but they are closely related chemically. This is shown not only by what the chemist knows of their constitution, but also by the readiness with which one passes into another, for example, the transformation of starch into dex- trose. Under the influence of certain agencies, such as 86 The Feeding of Animals heat, ferments and hot acids, certain carbohydrates may be changed to other bodies of the same class. This fact is important in the arts, and no less so in plant and animal nutrition. The movements of these com- pounds in plants and their uses as nutrients depend largely upon these transformations, as do also certain phenomena in cookery. Heat is one immediate cause of some of these changes. Starch, when heated, becomes dextrine, a water-soluble, gum -like substance. This occurs in baking corn and wheat bread; so it does in toasting bread, and the bread -crust tea of the sickroom is in part a solution of dextrine. Probably this substance is digested with greater ease than starch, because it is an intermediate stage between starch and glucose, the latter being the final product. Hot, dilute acids, even the vegetable acids, such as those found in vinegar and in fruits, transform starch, dextrin, gums and pectin bodies into various sugars, of which dextrose is the principal one. Saccharose is changed to dextrose and levulose in the same way. These chemical facts find an application in the manu- facture of glucose from cheaper materials, and in cook- ery where vinegar and acid fruits are used. These transformations are also brought about by the influence of bodies called ferments. For instance, the carbohydrates in a grain of barley are largely not available for nourishing the new growth that takes place during germination, because, being mostly insolu- ble, they cannot be transferred from the seed to the point where new tissue is formed. It is so arranged Nitrogen -free Extract — Carbohydrates 87 that a ferment present in the seed, called diastase, acts upon the starch and converts it into maltose, a sugar. The brewer takes advantage of this fact when he malts or germinates barley, this being nothing more than the same change of starch into sugar, which oc- curs during germination in the ground. This maltose is utilized by the young plant to form new tissue and by the brewer as a source of alcohol. In the animal body, especially in the mouth and intestines, are found ferments which accomplish essentially the same result. Through their diastatic influence the starch, dextrose, cane sugar and other carbohydrates are transformed, probably by successive stages, finally into glucose (dex- trose mainly) in which form the carbohydrate nutri- ents enter the blood. The chemical changes so far noted are all in one direction, i. e., the taking up of the elements of water to form new compounds, as, for instance, the trans- formation of starch to dextrose or cane sugar into in- vert sugar. Up to the present time, however, no chemist has discovered a way of reversing this process, and by ab- stracting the elements of water from the glucoses pro- ducing cellulose, starch and cane sugar. That the plant can do this, however, is certainly true. Cell walls and starch grains are undoubtedly made from the sugars under the influence of what we blindly call vital force. The carbohydrates, especially the sugars, possess such chemical properties as cause them to be easily de- stroyed and lost from the feeding stuff in which they are contained. If grass or corn fodder is allowed to lie 88 The Feeding of Animals in a mass in a green or wet condition, there is very material loss of dry matter, dne to the breaking up of the sugars aud other carbohydrates into new compounds under the influence of ferments. This action occurs in the silo, where the sugars are used to form considerable quantities of acids besides water and carbon dioxid. Loss from this cause often occurs in the grain bin, where new grain not sufficiently dry is stored. The sugars in canned vegetables or fruits that are not prop- erly heated or sealed soon disappear, either to be lost in gasecus products or to be converted into compounds of an entirely different character. All such fermenta- tions result in a diminished food value. Not only is there an actual disappearance of dry matter from the affected material, but this is brought about at the ex- pense of some of the most valuable food compounds. For this reason the farmer should exercise great care in the storage and preservation of his cattle foods. The dangers of loss from these fermentations are greater than is generally appreciated, for the cheinist finds that in drying green or wet foods under conditions more favorable than often pertain to farm practice he is un- able to avoid it to a greater or less extent. FATS OR OILS When any finely -ground feeding stuff, either straw or hay, is submitted to the leaching action of ether, chloroform, or certain other liquids, several compounds are taken into solution, the main and important ones being fats or oils. These bodies make up the chief Fats or Oils 89 portion of such an extract from seeds, while material so derived from hay, straw and other coarse fodders also contains a considerable amount of wax, chlorophyll and other substances. Tables that show the compo- sition of feeding stuffs have a column which is some- times designated "ether -extract," and sometimes "fats or oils." The former is the more accurate term, be- cause the compounds which it is the intention to de- scribe are often no more than half fats or oils. The real value of the "ether -extract " from different feed- ing stuffs is partly determined, therefore, by its source. When it is all oil, or nearly so, it is worth much more for use by the animal than when it is made up to quite an extent of other bodies. The proportions of fat or oil in feeding stuffs vary within wide limits. In general, seeds and their by- products contain more than the coarse foods, the differ- ences in the percentages of actual oil being greater than is indicated by the ether -extract. Straws natu- rally have less oil than the hays. But little is found in the dry matter of roots and tubers. Among the cereal grains and other more common farm seeds, corn and oats show the largest amounts, the proportion in dry matter being from five to six in one hundred, while wheat, barley, rye, peas, and rice contain much smaller percentages, wheat having about 2 per cent, and rice sometimes not over one -fifth of 1 per cent. Agri- cultural seeds that are especially oleaginous are cotton- seed, flaxseed, sunflower seeds, and the seeds of many species belonging to the mustard family, such as rape. Peanuts, cocoanuts and palm nuts are also very rich in 90 The Feeding of Animals oil. The average percentages in these seeds and nuts are approximately as given below: Oil in certain seeds Per cent Per cent Linseed 34 Peanuts 46 Cottonseed 30 Cocoanuts 07 Sunflower seed 32 Palm nuts 49 Rape seed 42 Poppy seed 41 Mustard seed 32 The oils from all the above are important commer- cial products, being used in a great variety of ways in human foods and in the arts. In many cases, the refuse from this extraction goes back to the farm as food for the cattle. This is especially true of linseed and cottonseed. The vegetable and animal fats and oils may, for convenience' sake, be discussed in two divisions, the neutral fats or glycerides and the fatty acids. The neutral fats are combinations of the fatty acids with glycerine. When, for instance, lard is treated at a high tempera- ture with the alkalies, potash and soda, glycerine is set free and an alkali takes its place in a union with the fatty acids. This is the chemical change which occurs in soap -making. There are several of these neu- tral fats, the ones most prominent and important in agriculture being those abundant in butter and in the body fats of animals; viz., butyrin, caproin, caprylin, caprin, laurin, myristin, olein, palmatin, and stearin. Butyrin is a combination of butyric acid and glycer- ine, stearin of stearic acid and glycerine, and so on. These individual fats possess greatly unlike physical Fats or Oils 91 properties. At the ordinary temperature of a room some are liquid and some are solid, olein belonging to the former class and palmatin and stearin to the latter. It is a matter of common observation that butter, lard and tallow differ in hardness at a given temperature, and by the use of a thermometer it may easily be dis- covered that their melting points are not the same. As these animal fats are in all cases chiefly mixtures of olein, palmatin, and stearin, stearin being a solid at ordinary temperatures, and olein a liquid at anything above the freezing point, it is evident that the relative proportions of these compounds will affect the ease of melting and the hardness of the mixtures of which they are a part. Tallow having more stearin than lard and butter aud less olein, is consequently much more solid on a hot day. Milk fat contains not only the three principal fats but also the others mentioned, butyrin, caproin, caprylin, caprin, laurin and myristin, in small proportions, and these latter tend to give butter certain properties that distinguish it from the other animal fats, which are almost wholly palmatin, olein and stearin. Doubtless the flavor, texture and resistance of butter to the effects of heat are much influenced by the proportions of the numerous fats it contains, but there is much connected with this subject of which we are still ignorant. Free, fatty acids exist in nature. They are not found in butter, lard and tallow unless these substances have undergone fermentations, or, as we say, have become rancid. The characteristic flavor of strong butter is due to free butyric acid, which, because of fermentations, 92 The Feeding of Animals has parted from the glycerine with which it was origi- nally combined in the milk. In plant oils, on the other hand, are found considerable proportions of the free fatty acids, some of which have not been discovered so far in animal fats, either free or uncombined. Perhaps no one has studied plant oils more thor- oughly than Stellwaag, who investigated the ingredients of the ether and benzine extracts from plants. His results show that not only do these extracts include substances which are not fats, but that a considerable proportion of free fatty acids is always present, some- times in quantities exceeding the neutral fats: Composition of ether -extracts {per cent) Neutral Free fatty Material not fats acids saponifiable Hay 23.7 37.3 30.8 Malt sprouts 24.7 30.1 34.5 Potatoes 16.3 56.9 10.9 Beets 23. 35.3 10.7 Maize, kernel 88.7 6.7 3.7 Barley. 73. 14. 6.1 Oats 61.6 27.6 2.4 It appears, as before stated, that ether -extract, es- pecially that from coarse fodders, may consist, to a large extent, of materials which should not be classed among the fats. Stellwaag demonstrated that only about 60 per cent of the hay extract which he investigated con- sisted of oil. On the contrary, the extracts from- the grains proved to be nearly all oil. Moreover, the grain oils were made up principally of glycerides, and those from hay, malt sprouts, potatoes and beets consisted largely of free fatty acids. CHAPTER VII THE COMPOSITION OF THE BODIES OF FARM ANIMALS The principal compounds existing in the bodies of our farm animals have been quite fully considered on preceding pages. It now remains for us to learn some- thing of the proportions of these substances that are needed in constructing the carcasses and other tissues of steers, sheep and swine; for it is about these spe- cies that we have the most extensive and accurate knowledge as related to chemical composition. Cer- tainly such knowledge is important. The animal is the direct product of food, and before we can consider intelligently the functions of food nutrients and the ways in which they are made to fulfil their offices, we must understand what is to be done. So far, then, as it is a matter of construction, what must be accom- plished by the use of food in building the bodj r of an animal ? It has doubtless become evident from fore- going statements that many compounds are common to the vegetable and the animal kingdoms. The chem- ical constituents in plants and animals are classified in the same way, also; viz., water, ash, or mineral com- pounds, protein, carbohydrates, and fats. Here the similarity stops, for the proportions of these classes as found in the fat steer and in the stalk of maize are (93) 94 The Feeding of Animals entirely unlike, and what is true in this respect of the steer and the maize is true of all other animals and plants. The dry matter of the vegetable world con- sists most largely of fiber, starch and other carbohy- drates, while animal tissues contain these compounds in so small a proportion as to be inappreciable in stat- ing the percentage composition. In the average animal dry matter, as it appears in the market, the fats are the leading constituents, and the proportion of protein is more than twice, perhaps three times, that in average vegetable tissue. In considering the composition of farm animals, we may first divide the body substances into water and dry matter. The dry matter, aside from the contents of the stomach and intestines, and the food ingredients in the way to being used, essentially belongs to three classes of compounds, ash, protein, and fats, which, as is the case with water, are present in greatly varying proportions in different species, and even in the same species according as the animal is young or old, lean or fat. Our knowledge on this subject is largely derived from the investigations of Lawes and Gilbert, at Roth- amsted, England. These investigators carried through the great effort of analyzing the entire bodies of ten animals representing two species at different ages, and three species in different conditions of fatness. At the Maine Experiment Station in this country, the bodies of four steers were analyzed, exclusive of the skin, two steers being younger and not so fat as the other two. From these data a very fair knowledge may be obtained not only of the composition of the bodies of bovines Composition of Farm Animals 95 » sheep, and swine, but also of the extent to which this composition is affected by age and condition : Composition of farm animals (per cent) Species Water Ash Protein Fat Ox, well-fed 66.2 5.9 19.2 8.7 Ox, half-fat 59. 5.2 18.3 17.5 Ox, fat 49.5 4.4 15.6 30.5 Sheep, lean 67.5 4. 18.3 10.2 Sheep, well-fed 63.2 3.9 17.4 15.5 Sheep, half-fat 58.9 3.8 16. 21.3 Sheep, fat 50.9 3.3 13.9 31.9 Sheep, very fat 43.3 3.1 12.2 41.4 Swine, well-fed 57.9 2.9 15. 24.2 Swine, fat 43.9 1.9 11.9 42.3 Fat calf 64.6 4.8 16.5 14.1 Steer, 17 -months 59.4 4.4 17.4 18.8 Steer, 17-months 57.1 5.2 17.5 20.2 Steer, 24-months 53.1 5.1 16.6 25.2 Steer, 24-months 53.4 5.2 16.8 24.6 It is always more or less surprising" to the learner to ascertain that the bodies of farm animals of vari- ous species and in various conditions are about half water. This is water that is not in any way chemically united with associated compounds, but exists in the blood and tissues in a free state, and may be dried out in the usual manner. Next to water, fat is the most abundant material, protein and ash following in the order named. Perhaps the most striking fact displayed is the great variation in the proportion of these ingredients accord- ing to the age and condition of the animal. For in- stance, the percentage of water in the fat calf is much 96 The Feeding of Animals greater than in the fat ox, and this is an illustration of a general truth, that mature animals are less watery than young ones. The amount of water present in the animal body is also influenced to a marked extent by the degree of fatness. The half -fat ox contained over 8 per cent more water than the fat, the store sheep 22 per cent more than the extra fat, and the store pig 14 per cent more than the fat. The explanation of this, as before stated, is not that fat replaces water already in the tissues of the lean animal, but that the increase is much more largely dry matter than was the original body substance. It is obviously true, also, that in fat- tening an ox or sheep, thus increasing the relative amount of fat, the proportions in the dry substance of ash and protein are decreased. The above statements are explained by the results obtained by Lawes and Gilbert in determining the composition of the increase while animals are fattening: Water Ash Protein Fat i i $ % Lean ox 66.2 5.9 19.2 8.7 Lean sheep 67.5 4. 18.3 10.2 Well-fed swine 57 9 2.9 15. 24.2 Average of lean animals .. . 63.9 4.3 17.5 14.3 Av. of increase while fattening 23.8 1.1 7.3 67.8 This comparison of the composition of lean animals and of the increase when they are fattened is a sufficient explanation of the less watery and fatter condition of the animal when ready for the market. The store animal is nearly two -thirds water and about one -sev- enth fat, while the increase is less than one -quarter Composition of Farm Animals 97 water and over two -thirds fat. The percentage of pro- tein in the increase is also very small. Not only does fattening an animal materially modify the composition, but the proportion of butcher 7 s meat is greatly increased- Proportion of dressed carcass (per cent) Ox Sheep Swine Lean animal 47. 45. 73. Fat animal 60. 53. 82. These slaughter tests were made by Lawes and Gilbert, and they explain in part why a fat steer is worth so much more per pound of live weight, even if the quality of the meat is no higher. It may be said, in a gen- eral way, that the carcass portion of the animal body varies with bovines and sheep from 50 to 65 per cent of the live weight, according to age and condition. SwiDe "dress away" not far from one -fifth. It would be possible to go further in our discussion of the animal body and consider it from the structural or anatomical point of view. It is certainly important to know something of the organs involved in digestion, respiration and assimilation if we would reach a clear understanding of how the food is made available and utilized, but such facts as are deemed necessary con- cerning these specialized tissues we will take up in their appropriate connections. G CHAPTER VIII THE DIGESTION OF FOOD We have accepted so far without discussion the almost self-evident fact that the food is the immediate source of the energy and substance of the animal body. It now remains for us to consider the way in which the nutrition of an animal is accomplished. The first step in this direction is the digestion of food. It is necessary for food ingredients to be placed in such relations to the animal organism that they are available for use. This involves both condition and location. The various nutrients in the exercise of their several functions must be generally distributed in all the interior parts of the animal. It is obvious that hay and grain as such cannot be so distributed, and so their compounds must, in part at least, be brought into a soluble and diffusible condi- tion, in order that they may pass through the mem- branous lining which separates the blood-vessels and other vascular bodies from the cavity of the alimentary canal. In discussing physiological relations of food, two terms are employed: viz., digestion and assimilation. Digestion refers to the preparation of food compounds for use, by rendering them soluble and diffusible, changes which are accomplished in what we call the ali- os) Digestion — Ferments 99 mentary canal, a passage that begins with the mouth, includes the stomach and intestines, and ends with the anus. Assimilation signifies the appropriation of nu- trients, after digestion, to the maintenance of energy and to the building of flesh and bones, processes taking place in the tissues, to which the nutritive substances are conveyed by the blood. The two terms are entirely distinct in meaning, although they are confused in popu- lar speech. In digestion, a feeding stuff undergoes both mechani- cal and chemical changes. It is masticated, that is, ground into finer particles, after which, in its passage along the alimentary canal, it comes in contact with several juices which profoundly modify it chemically. That portion of it which is rendered diffusible is ab- sorbed by certain vessels that are imbedded in the walls of the stomach and intestines, and is conveyed into the blood. The insoluble part passes on and is rejected by the animal as worthless material, and constitutes the solid excrement or feces. A study of digestion includes, then, a knowledge of mastication, of the sources, nature and functions of the several digestive juices, and a con- sideration of the various conditions affecting the extent and rapidity of digestive action. FERMENTS The changes involved in rendering food compounds soluble are intimately connected with a class of bodies known as ferments, to which brief reference has already been made in their relations to the preservation of feed- LofC. 100 The Feeding of Animals ing stuffs; and it seems necessary before proceeding to a consideration of digestion as a process to learn some- thing of the nature and functions of these agents, which are actively and essentially present in the digestive tract. A ferment may be denned in a general way as some- thing which causes fermentation; in other words, the decomposition of certain vegetable or animal compounds with which it comes in contact under favorable condi- tions. Ferments are of two kinds, organized and unor- ganized. Organized ferments are low, microscopic forms of vegetable life, generally single -celled plants. Unor- ganized ferments are not living organisms, but are sim- ply chemical compounds. When milk is allowed to remain in a warm room for several hours it becomes sour. An examination of it chemically shows that its sugar has largely or wholly disappeared and has been replaced by an acid. A study of the milk with the microscope, before and after sour- ing, reveals the fact that there has been a marvelous in- crease in it of single-celled organisms or plants. The growth of this form of life is "regarded as the cause of the change of the sugar into lactic acid. We have here the so-called lactic -acid ferment, which may typify the organized ferments known as bacteria. Numerous other fermentations of the same general kind are common to every- day experience. The changes in the cider barrel and the wine cask, the spoiling of canned fruits and vegetables, and the heating of hay and grain are illus- trations of what is accomplished by these minute organ- isms. Bacteria that cause disease, and which multiply in the organs and other tissues of the animal body, may Digestion — Ferments 101 also be properly called ferments, because in their growth new compounds are formed which are as truly fermenta- tive by-products as the carbonic acid and alcohol of cider and beer making. As this subject viewed on its patho- genic side is not important to the feeder, we need to study organized ferments only so far as they relate to the preservation of feeding stuffs and to changes in the alimentary canal. We shall be best equipped for con- trolling ferments and preventing their destructive action if we know what they are, and understand the general conditions under which they thrive. We should also know how, and to what extent, their action occasions harm. The organized ferments are classed in the vegetable kingdom. As a rule, each individual plant is a single cell, varying in shape and so minute as to be invisible to the unaided sight. It corresponds in its general structure to the cells which make up the tissues of the higher vegetable species, i. e., it consists of a cell wall inside of which are protoplasm and other forms of living matter. These organisms are distributed every- where, — in the air, in the soil, on surfaces of plants and in the bodies of animals. Whenever the right opportunity offers itself, they are ready to begin to multiply and bring about all the results attendant upon their growth. The conditions essential to their development are the proper degree of moisture and temperature and the necessary food materials. Thoroughly dry animal and vegetable substances do not ferment. Hay and grain that have been dried to a water content of 10 102 The Feeding of Animals per cent will keep a long time without loss from fer- mentative changes. The heat of a mow of new hay or of a bin of new grain, with its subsequent musty condition, is due to the fermentations that are made possible through the presence of considerable moisture. Thorough drying is a preventive of destructive fer- mentations. There is a temperature at which each vegetable fer- ment thrives best, and there are limits of temperature outside of which the growth of these forms of life does not occur, or is very slight. Numerous species thrive between 75° and 100° F. Fermentable materials like fruit and meat at the freezing point or below are not subject to fermentations. The boiling point of water kills most bacteria, and temperatures above 150° F. retard or entirely prevent their growth. Like all life, these organisms must have food. Many species find this in acceptable forms in vegetable products. Because they generally contain the sugar, albuminoids, and mineral compounds which nourish bacteria, feeding stuffs are always the prey of ferments under proper conditions of moisture and heat. The prevention of fermentation in cattle foods is desirable because it occasions a loss of nutritive value. This becomes evident when we consider the nature of the chemical changes that occur. For instance, when sugar is broken up through the influence of a bacterium, new compounds are formed which take up free oxygen. This means that combustion occurs, causing the lib- eration of energy which otherwise would have been available to the animal, if the sugar had been taken Digestion — Ferments 103 as food. Many fermentations involve oxidation, all of which are destructive of food value. Several theories have been advanced to account for the action of the orgauized ferments. The most plausi- ble seems to be that these little plants use sugar and other compounds as food, deriving energy there- from, the carbonic acid, alcohol and other new bodies being the by-products of this use. Whatever may be the real explanation of the changes that occur, fer- mentations due to plant growth are among the most useful agencies with which the farmer deals, and may be the most harmful. There is another class of ferments which is termed unorganized, and to which the general name enzym is given. These are the ferments especially important in digestion. They are merely chemical compounds which produce a peculiar effect upon certain bodies with which they come in contact. If a thin piece of lean beef be suspended in an extract from the mucous lining of a pig's stomach, to which has been added a small pro- portion of hydrochloric acid, the liquid being kept at about 98° F., the beef will soon begin to soften, after- wards swell to a more or less jelly-like condition and finally dissolve. The same general result would occur with fish, blood fibrin or the coagulated white of an egg. When starch, which is not affected by pure, warm water, is placed in a warm water solution of crushed malt it soon dissolves, leaving a comparatively clear liquid. A chemical examination of these preparations will reveal the fact that the compounds of the meat are present in solution in somewhat modified forms, 104 The Feeding of Animals and that the starch has been changed to a sugar or other soluble bodies. In both cases substances insolu- ble in water have become soluble and diffusible. The cause of these changes is the presence of typical bodies, one in the pig's stomach and one in the malt, ferments of the enzym class, the former of which ren- ders albuminoids soluble, the latter acting to produce a similar result with the insoluble carbohydrates. This action is different from that of the organized ferments, where oxidation occurs in many cases. The enzyms simply induce the albuminoids and starch to take up the elements of water, which apparently does not greatly diminish their energy value. How this is done cannot be explained in simple terms, if at all. Our knowledge of the manner of the change rests entirely upon theo- retical grounds. The digestion of food is almost wholly accomplished through the specific effect of enzjmi bod- ies, of which every digestive fluid contains one or more. Examples of these are the pepsin and pan- creatin of the drug store that contain enzyms mixed with more or less impurities. The function of each of these ferments we shall consider as we proceed to discuss the various steps of digestion. THE MOUTH The first step in the digestion of fodders and whole grains is to reduce them to a much finer condition. This is done in the mouth, the teeth being the grind- ing tools.* Sometimes the cutting or grinding is par- * This is not true of hens, turkeys and other fowls. Digestion — The Mouth 105 tiall}* or wholly performed for the animal in hay-cutters and grain mills. However this may be accomplished, it is an essential operation for two reasons, (1) it puts the food in condition to be swallowed, and (2) fits it for the prompt and efficient action of the several diges- tive fluids. Dry whole hay or kernels of grain could hardly be forced down the tube leading to the animal's stomach. It is necessary for these materials to be" broken down and moistened in order that they may be swallowed. Even if they could be conveyed to the stomach in their natural condition the process of ren- dering their constituents soluble would proceed very slowly. Common experience teaches us how much more quickly finely powdered sugar or salt will dis- solve than the large crystals or lumps. The more finely any solid is ground, the larger is the surface ex- posed to the attack of the dissolving liquid, and this is as true of foods as of sugar or salt. Prompt and rapid solution of food is essential, be- cause if it is too long delayed, uncomfortable and in- jurious fermentations are likely to set in, and because of imperfect digestion, the final nutritive effect of the ration may be diminished. For these reasons, animals with diseased teeth, or those that have lost teeth, make poor use of their food, and require an unneces- sary amount to keep them in condition. These condi- tions may often be a cause, especially with horses, of disappointing results from an ordinarily sufficient ration. The teeth of our domestic animals differ somewhat in number and arrangement. Authorities state the following to be the usual number: 106 The Feeding of Animals Total Incisors Canines Molars Horse 36-40 12 4 24 Ox 32 8 24 Sheep and goat 32 8 24 Pig 44 12 4 28 The incisors or front teeth are those which are used for prehension, and by grazing animals for cutting off the grass and other herbages. With the ox, sheep and goat, incisors are found only in the lower jaw. These shut against a tough pad on the upper jaw. They are constantly wearing off, and with old animals may be so worn away as to leave only the roots. Such animals do not graze successfully. With the horse and pig, in- cisors are found in equal numbers in both jaws. The molars are the grinding teeth. Those of the horse sometimes need filing on the outside edges in order to prevent irritation and soreness of the adjacent tissues. A diseased molar may occasion an animal much discomfort and cause imperfect mastication. During mastication there is poured into the mouth a liquid called the saliva, which has two important functions: (1) it moistens the food, and (2) with sev- eral species of animals it causes a chemical change in certain of the constituents of the food. The saliva has its origin in several secretory glands that are adjacent to the mouth cavity, and from these this liquid is poured into the mouth through ducts that open in the cheek under the tongue. The chief of these glands are located in the side of the face, below and somewhat back of the jaws and beneath the tongue, and are called the parotid, the submaxillary and the Digestion— The Mouth 107 sublingual. Other glands of this character are scat- tered in the cheeks and at the base of the tongue. The anatomy and arrangement of these organs are not essential to our subject. We are chiefly interested in the liquid which they secrete. The saliva is a transparent and somewhat slimy liquid, and contains generally not less than 99 parts in 100 of water, and one part or less of solid matter. It is alkaline in reaction, because of the presence of compounds of the alkalies. The specific chemical effect exerted by this liquid on the food constituents may be illustrated by subjecting starch to its action. When this is done, the starch gradually disappears as such and is replaced by maltose, the same sugar that we find in barley malt. The chemist has learned that the agent which is active in causing this change is a ferment, to which the name ptyalin has been given, and which is always present in the saliva of man and of some animals. It is classed among the diastatic ferments, because it has an office similar to that of diastase in the germination of seeds; viz., the trans- formation of the starch into a sugar. This change begins in the mouth and probably continues in the stomach until the food becomes so acid that the fer- ment ceases to act, for ptyalin is inactive except in an alkaline medium. There is no reason for supposing that any considerable proportion of the starch of a ration is transformed by the saliva, but this solvent action which continues later in the digestive processes certainly begins in the mouth in the manner described. The saliva also moistens the food, which is a most 108 The Feeding of Animals important office, for it is a necessary preparation to the act of swallowing. With large rnminants, the quantity of saliva required for this purpose is large, as is evident when we remember that an ox or cow may consume in one day 24 pounds of very dry hay and grain, and that rumination goes on much of the time while the animal is not eating. It is estimated that oxen and horses se- crete from 88 to 132 pounds daily, an apparently enor- mous quantity of liquid for secreting organs no larger than the salivary glands to supply. THE STOMACH When the food leaves the mouth, it passes down the gullet (oesophagus) into the stomach. The only modi- fications it has suffered up to this point are its reduction to a finer condition and a slight action of the mouth ferment upon the starch, an influence which doubtless continues in the stomach for a larger or shorter pe- riod, according to circumstances. After the food is swallowed changes of another kind begin sooner or later, affecting the protein compounds especially. Before considering gastric digestion from a chemi- cal point of view, we should become acquainted with the widely differing structure of the stomachs of the various farm animals. Those of the ox and horse are greatly unlike. The stomach of the ox, and of all other ruminants, consists of four divisions or sacs, whereas with the horse and pig it is made up of a single sac. The ruminant stomach is really quite a complicated affair, and the way in which it disposes of the food is Digestion — The Stomach 109 understood only after a careful study of details. Its four divisions or sacs are the paunch, honeycomb, many -plies and rennet, or what the physiologist has named the rumen, reticulum, omasum and abomasum. With the ox these cavities contain on the average not far from fifty -five gallons, about nine -tenths of this space belonging to the paunch. Fig. 1. Fig. 1. Stomach of ox. T, rumen or paunch, showing attachment of oesophagus. C, reticulum or honeycomb. O, omasum or many-plies. A, abomasum or rennet, showing attachment of small intestine. The food, in its descent from ,the mouth, passes at first mostly into the paunch through a slit in the gul- let. This cavity, as stated, is very large, and it may properly be considered as an immense reservoir for the storage of the bulky materials which the ruminants take as food. As is the case with the entire digestive canal, the walls of the paunch are composed of three layers of tissue, the middle one being a very thick 110 The Feeding of Animals muscular coat, which seems necessary to produce the movement of large masses of food. The inner or mucous layer is covered with numerous leaflike pro- jections, in which the blood-vessels are freely distrib- uted. During its stay in this reservoir, the moist food becomes thoroughly softened and besides undergoes a variety of changes, chiefly those due to the organized ferments combined perhaps with the continued action of the saliva. These fermentations cause an almost constant evolution of gases, which are as constantly absorbed by the blood. It is suggested that the rapid puffing up of the paunch of a freshly -killed bovine is due to the failure of the blood to take up these gases. Sometimes unnatural and dangerous fermentations set in, induced often by the consumption in the spring of a large quantity of easily fermentable food such as green clover. This causes hoven, and unless the gas pressure is at once relieved by an opening into the paunch the animal dies, often after the bursting of the rumen. A portion of the food reaches the reticulum or honeycomb, either through the cesophagal slit when first swallowed, or through a large opening between the paunch and the honeycomb. The reticulum also communicates with the third stomach by an opening. This is the smallest division of the stomach, and de- rives its common name from the fact that its interior surface is divided by ridges of the mucous membrane into cells which bear a close resemblance to a honey- comb. These cells, which are several sided and quite deep, appear to be a "catch-all" for the foreign bodies Digestion — The Stomach 111 which animals are liable to swallow, such as small stones, pins and nails. The contents of this compart- ment of the stomach are very watery, a condition which is said to aid the return of the food to the mouth, por- tion by portion, for remastication. Rumination, which is the re -chewing of food pre- viously swallowed, is peculiar to bovines, sheep and goats. In the case of these species, the mastication of coarse fodder is not completed before it is swallowed the first time, and they have the power of returning to the mouth the material which has become stored in the paunch and honeycomb in order that it may be more finely ground. This is what is termed "chewing the cud." It is an operation which greatly aids digestion in rendering the food mass finer and more susceptible to the action of the digestive fluids. Animals fed on grain alone do not ruminate. They "lose their cud," a condition popularly and erroneously supposed to be fatal to the animal's life. After remastication, the food does not return wholly to the first and second stomachs, but is mostly carried along in what is known as the oesophagal groove to the third stomach, the omasum. The finer portions may even do this when first swallowed. The many -plies (omasum) is a cavity somewhat larger than the honey- comb, which has a most curious interior structure. It is filled with extensions of the mucous membrane in the form of leaves, between which the food passes in thin sheets, an arrangement which seems to have for its purpose the further grinding of the food so that when it finally reaches the fourth and last compart- 112 . The Feeding of Animals ment it is in a very finely -divided condition and is thoroughly prepared for the action of the juices that are subsequently poured upon it. It is at the last stage of the journey of the food through this complicated stomach that it is submitted to the true gastric digestion. As a matter of fact, the abomasum or rennet is regarded as the true stomach, the other three sacs being considered as enlargements of the oesophagus. In the calf, the rennet is the only part developed, the other divisions not coming into use until the animal takes coarse foods in considerable quantity. The fourth stomach is larger than either the second or third. It receives directly from the omasum the finely divided food, upon which it pours the gastric juice, a liquid that is secreted in large quantity by glands located in its inner or mucous membrane. This juice, like all the digestive fluids, is mostly water, the proportion being between 98 and 99 parts to less than two parts of solids. The latter consist of ferments, a certain amount of free or uncombined hydrochloric acid and a variety of mineral compounds, prominent among which are calcium and magnesium phosphates and the chlorides of the alka- lies, common salt being especially abundant. Especial interest pertains to the ferments of the gas- tric juice, one of which, in connection with free hydro- chloric acid, causes a most important change in the proteids of the food by reducing albuminoids, such as the gliadin and glutenin of the wheat kernel to soluble forms. We know quite definitely about this action, because it can be very successfully produced in an ar- Digestion — The Stomach 113 tificially prepared liquid. If the mucous lining of a pig's stomach, after carefully cleaning without washing with water, is warmed for some hours in a very dilute solution of hydrochloric acid, an extract is obtained which has the power of dissolving lean meat, wheat gluten and other proteid substances. The active agent in causing this solution is pepsin, an unorganized fer- ment or enzym which is present in the gastric fluid of all animals. It changes albuminoids to peptones, bod- ies so soluble and diffusible that they pass readily into certain small vessels which are distributed in the walls of the alimentary canal and thus become available as nutrients. The other ferment present in the gastric juice is the one which gives to rennet its value as a means of coagulating the casein of milk in cheese- making, and is called rennin. The action of this latter body is especially prominent in the stomach of the calf when fed exclusively on milk, and it is the calf's active stomach, the fourth in the mature animal, which is the source of commercial rennet. The free hydrochloric acid in the gastric juice is also actively concerned in proteid digestion. It is found that a solution of pepsin has little or no effect in the absence of free acid, for when, during artificial diges- tion, the supply of this acid is used up it must be renewed or digestion ceases. The stomach of the horse and pig consists of a single sac, so that digestion with these animals is a much simpler matter mechanically than with ruminants. Chemically, the results are essentially similar, i. e., the protein is in part changed to peptones. The food, after H 114 The Feeding of Animals being swallowed, is not returned to the mouth, but is very soon brought under the action of the gastric juice without so long -continued pre- liminary preparation by remas- tication and trituration . For this reason the horse fails to digest coarse fodders so com- pletely as the ox does. Besides, the stomachs of the horse and pig are too small to admit of so large an ingestion of hay or similar material, as is the case with ruminants of similar size. a, pyloric end of stomach, with In all species, however, the beginning of small intestine. chemical regult Q f stomach digestion is essentially the same, i. e., the protein is in part changed to peptones. Fig. 2. Fig. 2. Stomach of horse. B, cesophagal attachment. THE INTESTINES The most extended portion of the alimentary canal, though not the most capacious in all cases, is the in- testines. They consist of a tube differing in size in its various portions, which begins with the stomach and ends with the anus. This tube is not a straight passage between the points named, but presents curves and folds, so that when straightened out it appears sur- prisingly long. Its average length with the ox is given as 187 feet, sheep 107 feet, horse 98 feet, and hog 77 feet, lengths which are from twelve to twenty - seven times that of the body of the animal. The intes- Digestion — The Intestines 115 tines are divided into large and small, the latter being from three to four times as large as the former. When the food leaves the stomach, it enters the small intestines. At this point it is only partially digested. The fats are probably so far unchanged and, without doubt, the larger proportion of the proteids and carbohydrates that are susceptible of solution is still in the original condition. Hardly has this par- tially dissolved material passed into the small intes- tines before it comes in contact with two new liquids which are poured upon it simultaneously or nearly so; viz., the bile and the pancreatic juice, and the changes which began in the mouth and stomach, together with others which set in for the first time, proceed vigor- ously. The bile has its source in the liver. It is a secre- tion of this organ, and after elaboration it is stored in a small sac attached to the liver which is called the "gall bladder," and from which gall is conveyed to the intestines through a duct opening very near the orifice leading out of the stomach. Bile is a liquid varying when fresh from a golden red color in man to a grass -green or olive -green in certain herbiverous animals. It is slightly alkaline, bitter to the taste and without odor. The specific and characteristic con- stituents of the bile are two acids, glycocholic and taurocholic, that are combined with sodium and are associated with two coloring matters, bilirubin and biliverdin. Numerous other compounds are present in very small proportions, such as fats, soaps and min- eral compounds, but they appear to have no important 116 The Feeding of Animals relation to digestion. If any ferment is present at all, it is only as a trace, and therefore the bile is incapable of effecting decomposition of the proteids and carbo- hydrates, such as occur in the mouth and stomach. This is shown by experiments. Nevertheless, this liquid must be regarded as having a real digestive function, which it exerts in two ways, (1) by preparing the chyme (partially digested food from the stomach) for the action of the pancreatic juice and (2) in acting upon the fats in such a way as to render their absorption possible. We have learned that pepsin, the stomach ferment, acts upon proteids only in an acid medium. The oppo- site is true of the ferments which the food meets in the intestines, for these require an alkaline condition. The bile tends to neutralize the acidity of the chyme, and in this, as well as by other chemical changes too complex for discussion here, prepares the way for the pancreatic juice to do its work. The most important discovery so far made in con- nection with the bile is the fact that when its entrance into the intestines is prevented the fat of the food largely passes off in the feces. This proves that in some way the liver secretion is essential to the digestion of fats. The ordinary and probably correct explanation of what takes place is that, while bile does not decom- pose the fats in any way, it is able, in connection with certain influences of the pancreatic juice, to reduce them to an emulsion, i. e., to a condition of suspension in a liquid in very finely divided particles, a form in which they are able to pass into the blood. It is believed Digestion — Intestines 117 that the bile has more or less antiseptic influence and so prevents the intestinal contents from undergoing putrefactive fermentation, which would have the effect of greatly increasing the offensive odor of the feces. The pancreatic juice has a more complex function in digestion than that of any other digestive fluid. It is known to contain at least three distinct ferments, each of which has its own peculiar effect upon each of the three classes of food constituents. This juice reaches the food at practically the same time as the bile. It comes from the pancreas, a gland known to butchers as the "sweet bread," and enters the intestine through a small duct which in some animals is confluent with the bile duct. It is somewhat gluey in character, of alkaline reaction and has a saltish taste. First of all, the pancreatic juice has, in a marked degree, the power of digesting proteids in an alkaline medium. This power is due to a ferment known as trypsin, which converts proteids to peptones, and cor- responds in its function, therefore, to the pepsin of the stomach. Under the influence of this ferment the proteids are also, to some extent, split into simpler bodies. The transformation of starch into sugar and other soluble bodies, which ceased in the stomach, is again taken up through the influence of a diastatic ferment present in the pancreatic juice, and proceeds vigorously. A third enzym, also present, is one that has the power of splitting the neutral fats into fatty acids and glycer- ine, a change which appears to have an important rela- tion to the emulsionizing of fats. As before intimated, 118 The Feeding of Animals the bile and the pancreatic juice appear to share the function of fat digestion. As the intestinal contents pass along-, they come in contact with a juice secreted by the walls of the intes- tines, the action of which has been carefully studied. It has been found that this liquid has no action on the proteids or fats, but that it is able to convert starch into soluble bodies, and especially has the peculiar prop- erty of transforming into glucose the maltose arising from previous digestion, glucose being the form in which all digested carbohydrates are supposed to enter the circulation. It seems, then, that the intestinal juice supplements the action of the other digestive fluids, so far as carbohydrates are concerned, completing starch digestion and preparing the sugars for absorption, and when we consider that from 80 to 90 per cent of the food of our farm animals consists of carbohydrates the great importance of this office is apparent. From the time the food enters the stomach until the undigested residue leaves the bod}^ the contents of the alimentary canal are subjected to fermentations caused by organized ferments, resulting in the evolution of acids, gases and certain other compounds formed from the proteids, which give to the feces its offensive odor. Just what relation these fermentations have to the di- gestion of food we are not able to state. There are strong reasons for believing that crude fiber (cellulose), during its stay in the first stomach, is the subject of their action, and its digestion may be wholly brought about in this way. Such fermentations become promi- nent only when, because real digestion does not proceed Food Absorption 119 normally, they are given an opportunity to develop with unusual activity and cause bloat, colic and offensive odors in the solid excrement. ABSORPTION OF THE FOOD From the time the food enters the stomach, during nearly its entire course along the alimentary canal, there is a constant production of soluble compounds, which progressively disappear into other channels, so that when the anus is reached only a portion of the original dry matter is found in the residue. In some way, not wholly explainable in all its details, the digested food has been absorbed and received into vessels through w T hich it is distributed to the various parts of the body. A merely casual observation shows us that the inner surface of the walls of the digestive organs are covered by numerous projections. The anatomist, by a careful study of these, has learned that imbedded in their tis- sue, especially in the intestines, are the minute branches of two systems of vessels. One set is the lacteals be- longing to the so-called lymphatic system and the other set is the capillaries of the blood system. The lym- phatic vessels or tubes all lead to a main tube or reser- voir, the thoracic duct, which extends along the spinal column and finally enters one of the main blood-vessels. Any material, therefore, taken up by the lacteals ulti- mately reaches the blood. The capillaries all converge to a larger blood-vessel, known as the portal vein, which enters the liver, carrying with it whatever material the- capillaries have absorbed. 120 The Feeding of Animals The manner in which the soluble food is absorbed may be explained in part on common physical grounds. When two solutions of different densities, containing diffusible compounds, are separated by a permeable membrane, diffusion through this membrane from the denser to the lighter liquid will always occur. Such a condition as this prevails in the intestines, we may be- lieve. The intestinal solution, the denser one, is sep- arated from a less concentrated liquid, the blood, which is constantly flowing on the other side of a thin dividing membrane. Under these conditions only one thing can occur; viz., the passage into the blood of certain parts of the digested food. It is held that in this way w r ater, soluble mineral salts and sugar pass directly into the blood-vessels. The peptones are taken up largely by lacteals and the fats enter the blood entirely through this channel. In the absorption of peptones, we encounter forces other than those which pertain to the mere diffusion of liquids, the operation of which is still more or less shrouded in mystery. As we have learned, the proteids are largely changed to peptone in the stomach and in- testines, but, strange as it may seem, no peptone is found in the blood. At some point in its passage through the lining tissues of the digestive tract, it has been regenerated into forms more nearly like those from which it is derived. Moreover, the absorption of fats is regarded as being accomplished through the activity of certain cells or corpuscles, which appear to convey this portion of the food to the lacteals. It seems, then, that the vital forces residing in the living animal cells Undigested Residue — Why Digestibility Varies 121 play a part in transferring the nutrients into the blood circulation, and that this absorption can no longer be explained wholly on physical grounds. FECES The soluble and insoluble portions of the intestinal contents become separated gradually, and the undissolved part arrives finally at the last stage of its journey along the alimentary canal and is expelled as the solid excre- ment or feces. This is made up of the undigested food and a small proportion of other matter, such as residues from the bile and other digestive juices, mucus and more or less of the epithelial cells, which have become detached from the walls of the stomach and intestines. Very small quantities of fermentation products are present also, which give to the feces its offensive odor. The incidental or waste products may properly be con- sidered as belonging to the wear and tear of digestion THE RELATION OF THE DIFFERENT FEEDING STUFF COMPOUNDS TO THE DIGESTIVE PROCESSES Numerous digestion experiments with a large variety of feeding stuffs have abundantly established the fact that these materials differ greatly in their solubility in the digestive juices. This is an important matter, and one which should be well understood, for we must con- sider both the weight of a ration and its availability in determining its nutritive value. Variations in diges- tibility are caused primarily by variations in composi- 122 The Feeding of Animals tioii. The low digestibility of wheat straw, as compared with that of the wheat kernel, is due to the absence in one of compounds that are abundant in the other. We, therefore, must deal fundamentally with the suscepti- bility of the various single constituents of plants to the dissolving action of the several digestive ferments. In this connection, we need to pay little attention to the mineral compounds. They do not undergo fermen- tative changes in the way that the carbon compounds do, but pass into simple solution either in the water accompanying the food, or in the juices with which they come in contact. As has been noted, protein is a mixture of nitrog- enous compounds, largely albuminoids. The gluten of wheat contains at least five of these bodies, and other seeds as many. What is the relative susceptibility of these single proteids to ferment action either as to ra- pidity or completeness of change does not appear to be known. Some albuminoids are practically all digested by artificial methods, and probably are in natural di- gestion. It is a fact, however, that protein is much more completely dissolved from some feeding stuffs than from others. That of milk is all digestible, that of some grains very largely so, while with the fodders quite a large proportion escapes solution. Whether this is due to a differing degree of solubility on the part of the characteristic protein compounds of these feeding stuffs is not quite determined. The fact that highly fibrous materials show the lowest proportion of digestible pro- tein suggests as an explanation that the nitrogen com- pounds of the coarse fodders are so protected by the 7\luj Digestibility Varies 123 large amount of fiber present that they escape the full action of the digestive juices. It is certain, anyway, that the protein of young and tender tissues and of the grains is more fully digested than that of the hays and straws. In the case of the carbohydrates, our knowledge of the relative susceptibility of the individual compounds to enzym action is more definite. First of all, the nec- essary modification of the sugars, which are already soluble, is slight, and they are wholly digested. In the second place, we have learned in two ways that the starches are wholly transformed to diffusible compounds, first by submitting them in an artificial way to the ac- tion of various diastatic ferments, and, second, by dis- covering a complete absence of starch or its products in the feces of our domestic animals. In no case that has come under the writer's notice has either starch or sugar been found in the solid excrement. We can say, there- fore, that under normal conditions the starches, like the sugars, are completely digestible. Digestibility must be considered, however, from the standpoints both of rapidity and of completeness. As to the former factor, starches from unlike sources ex- hibit some remarkable differences. Investigations by 8 tone, who submitted a. number of these bodies to the action of several diastatic ferments, show that "this variation reaches such a degree that under precisely the same conditions certain of the starches require eighty times as long as others for complete solution." The potato starches appear to be acted upon much more rapidly than those from the cereal grains. 124 The Feeding of Animals Other carbohydrates and related substances, such as the gums and cellulose, do not undergo complete digestion, sometimes half or more of these compounds escaping solution. Stone, after examining twenty feed- ing stuffs and the fecal residues obtained from them in digestion experiments, found in the feeding stuffs from 6 to 16 per cent of gums, 46 to 77 per cent of which was digested, the average being 58 per cent. Crude fiber proves to be digestible within about the same limits, or 36 to 80 per cent with American fodders. We are much in the dark concerning the manner of diges- tion of the gums and crude fiber. To what extent these substances are the subjects of purely fermentative changes, or of merely chemical decompositions, is not known at present, but the fact of a partial digestion is well established whatever may be the causes involved. The extent of the digestion and absorption of the fats or oils is also not definitely known. If we were to accept the figures given for ether extract in tables of digestion coefficient as applying to the real fats we would believe that their digestibility varies from less than one -third to the total amount. It is unfortunately true that these coefficients mean but very little. The ether extract from the feeding stuffs is only partially fat or oil, as we have seen, and the inaccuracy of a digestion trial is still further aggravated by the pres- ence in the feces of bile residues and other bodies which are soluble in ether, so that the difference between the ether extract in the ration and that in the feces gives us little information as to what has happened to the actual fats. It seems very probable that pure vegetable Why Digestibility Varies 125 fats and oils are quite completely emulsified and ab- sorbed. The foregoing statements make it plain that when the general composition of a feeding stuff is known it is possible to predict with a good degree of certainty whether its rate of digestibility is high or low. The larger the proportion of starch and sugar and the smaller the percentage of gums and fiber, the more complete will be the solution. We see this illustrated in the ex- treme by the difference in digestibility of corn meal and of wheat straw. «#•**> CHAPTER IX CONDITIONS INFLUENCING DIGESTION The chemical changes and other phenomena consti- tuting* digestion, which have been described as occurring in the alimentary canal, are practically outside the con- trol of the one who feeds the animals. They proceed in accordance with fixed chemical and physiological laws. It is, however, within the power of the feeder to so manipulate the food or vary the conditions under which it is fed that the extent or completeness of diges- tion is modified, and this must be regarded as an im- portant matter when we remember that only the digested food is useful. PALATABLENESS It is entirely reasonable to believe that a thorough relish for food is conducive to good digestion. The secretion of the digestive juices is not a mechanical process, but is under the control of the nervous system. With man, at least, the enjoyment of eating, even its anticipation, stimulates the secretory power of the sal- ivary glands and those in the mucus lining of the stomach, and it is evident that this holds true with animals. Palatableness is, therefore, an important fac- tor in successful feeding, for it tends to promote a (126) Influence of Palatableness, Quantity 127 state of vigorous activity on the part of the digestive organs. The experienced feeder knows well the value of stimulating the appetite of his animals by means of attractive mixtures. An agreeable flavor or taste adds nothing to the energy or building capacity of a food, but it does tend to secure a thorough appropriation of the nutrients which enter the alimentary canal. With- out doubt, the success of one feeder as compared with the failure of another may sometimes be due, in part, to a superior manner of presenting a ration to the animal's attention and to manipulations that add to the agreeableness of its flavors. INFLUENCE OF QUANTITY OF RATION Early experiments by Wolff, in which he fed larger and smaller rations of the same fodder to the same animals, have been made the authority for the state- ment that a full ration is as completely digested as a scanty one, provided the former does not pass the nor- mal capacity of the animal. It must be said, however, that the testimony concerning this point is not unani- mous. Since Wolff's experiments, Weiske, in feeding oats to rabbits, found the digestibility to be inversely as the quantity of food taken. In experiments with oxen, by G. Kiihn, at Mockern, when the grain ra- tion was doubled the digestibility of the malt sprouts used was decreased about nine per cent. Results at the New York Experiment Station from feeding full and half rations to four sheep showed uniformly higher digestion coefficients with the smaller ration, the differ- 128 • The Feeding of Animals enees being too large and too constant to be considered accidental. Other experiments give varying and con- flicting figures. If we assume that the constituents of feeding stuffs have a certain fixed solubility in the di- gestive fluids, then within reasonable limits the amount of food should have no effect upon the proportions of nutrients digested, but such an assumption cannot safely be made. Doubtless no single statement concerning this point will be found applicable to all animals and all rations. Certainly, overfeeding may lessen the extent of solution and is never wise, while under -feeding for the sake of securing a maximum digestibility would not be good practice. It is reasonable to suppose, however, that the relation in quantity between the enzj^ms and the food compounds has an influence, at least, upon the rapidity of digestion ; and indeed investigations by Stone very strongly point to such a conclusion, for he found that the rate of ferment action was proportional to the concentration of the ferment solution. EFFECT OF DRYING FODDERS At one time the belief became very firmly fixed in the public mind that curing a fodder causes a material decrease in its digestibility. Because this drying is often carried on under conditions that admit of de- structive fermentations or of a loss of the finer parts of the plant, this view is probably correct for partic- ular cases, but if it is accomplished promptly and in a way that precludes fermentation or loss of leaves it is Treatment of Fodders 129 doubtful if curing has any material effect upon digesti- bility. The point has been the object of six American di- gestion experiments, Hungarian, timothy, pasture grass, corn fodder, crimson clover and winter vetch being the experimental foods. With four of these slight, but un- important, differences were observed in favor of the dried material, while the reverse was decidedly true of the crimson clover and the corn fodder. German ex- periments show in a majority of cases greater digesti- bility for the green fodders. It seems probable that in general practice, because of greater or less unavoid- able fermentation and a loss of the finer parts of the plant, dried fodders have a somewhat lower rate of digestibility than the original green material, a fact not due directly to drjdng, but to a decrease, either of the more soluble compounds or of the tender tissues. INFLUENCE OF THE CONDITIONS AND METHODS OF PRESERVING FODDERS Iii comparing the conditions and methods of pre- serving fodders in their relation to digestibility, we may safely rest upon the general statement that when, for any cause, leaching occurs or fermentations set in, di- gestibility is depressed. The explanation of this state- ment is that those compounds of the plant which are entirely soluble in the digestive fluids, notably the sugars, are the ones wholly or partially removed or destroyed by leaching or fermentations, while the more insoluble bodies remain unaffected. When, therefore, hay is cured under adverse conditions, such as long -con- 130 . The Feeding of Animals tinued rain, digestibility is decreased, and the same effect is inevitable from the changes which occur in a ferment- ing mass, such as a mow of wet hay, a pile of corn- stalks or the contents of a silo. Experimental evidence of the truth of these statements is not wanting. Ger- man digestion trials with alfalfa and esparsette, green, carefully dried, cured in the ordinary way, fermented after partial drying and as silage, show a gradually decreasing digestibility from the first condition to the last. A single American experiment, comparing the same fodder both green and as silage, gives testimony in the same direction. On the other hand, field -cured corn fodder, according to nine out of eleven American ex- periments, is considerably less digestible than silage coming from the same source. Here it is largely a question of the relative loss by fermentation in the two cases, and it is t.o be expected that the outcome would not be wholly one way. INFLUENCE OF THE STAGE OF GROWTH OF THE PLANT Another generalization, which certainly must hold good with reference to the digestibility of fodder plants, is that any conditions of development which favor a relatively large proportion of the more soluble carbo hydrates; viz., starches and sugars, and secure a min- imum of gums and fiber, promote a high rate of diges- tibility, and reverse conditions produce the opposite result. It is well known that, in general, as the meadow grasses mature the relative proportion of fiber increases and the tissue becomes harder and more resisting. Nu- Stage of Growth, Preparation 131 merous American and European digestion trials unite in testifying almost unanimously to a gradually diminished digestibility as the meadow grasses increase in age. The maturing of maize seems to produce quite the con- trary effect. The testimony of experiments conducted at the Connecticut, Maine and Pennsylvania Experiment Stations justifies the statement that the corn plant, cut when the ears are full grown, furnishes not only a larger amount of digestible material, but a larger relative pro- portion than when cut before the ears have formed; and this is strictly in harmony with our general prin- ciple; for the mature plant, on account of the storage of starch in the kernels, has by far a larger proportion of the more digestible carbohydrates. INFLUENCE OF METHODS OF PREPARATION OF FOOD Much labor and expense have been expended by farmers in giving to feeding stuffs special treatment, such as wetting, steaming, cooking and fermenting, in order to secure a supposed increase in nutritive value, an increase which must come chiefly, if at all, from a more complete digestion. It is plainly noticeable that these methods of feeding have lost in prevalence rather than gained. Practice does not seem to have perma- nently ratified them, and, so far as digestibility is concerned, this outcome is in accordance with the re- sults of scientific demonstration. The conclusions of German experimenters have been that these special treatments have no favorable influence, their effect being either imperceptible or unfavorable. 132 • The Feeding of Animals It should occasion no surprise that the mere wetting of a food is without influence upon its solubility in the digestive juices, because it becomes thoroughly mois- tened during mastication and in the stomach. It is not rational to expect that previous wetting would have the slightest effect unless it induced more complete mastication, which certainly would not be the case with ground grains. The extensive trials by Kiihn and others with a hay and bran ration, the bran being fed in several conditions, such as dry, wet, moistened some hours before feeding, treated with boiling water and fermented, gave results adverse to all of the special methods of preparation as either useless or harmful, and no testimony so thorough and convincing has been furnished on the other side. German and American experiments unite in con- demning the cooking of foods already palatable, because this causes a marked depression of the digestibility of the protein, with no compensating advantages. Diges- tion trials with cooked or steamed hays, silage, lupine seed, cornmeal and wheat bran, and roasted cotton seed, uniformly show their protein to be notably less digestible than that in the original materials, a fact which may explain the lessened productive value of cooked grains which has been observed in certain ex- periments. It must be conceded, of course, that when cooking feeding stuffs by steaming or otherwise renders them more palatable, and thereby makes pos- sible the consumption of material otherwise wasted, the influence upon digestibility is a minor consid- eration. Influence of Grinding and of Salt 133 INFLUENCE OF GRINDING Few points are more frequently questioned than the profitableness of grinding grain. There seem to be only two ways in which such preparation can enhance the nutritive value of a feeding stuff; viz., by dimin- ishing the energy needed for the digestive processes and by increasing the digestibility. While only about a half-dozen experiments bearing upon the digestion side of this question are on record, their evidence is quite emphatic. In three trials with horses, with both corn and oats, grinding caused an increase of digesti- bility varying from 3.3 to 14 per cent. A single experiment with maize kernels gave a greater diges- tibility of about 7 per cent from grinding, and with wheat, in one trial, the increase was 10 per cent. In one test of oats with sheep, the unground kernels were as completely utilized as the ground. It is reasonable to expect that with ruminants the danger of imperfect mastication is less than with horses and swine, although whole kernels of grain are often seen in the feces of bovines. The profitableness of grinding grain Hums, in part at least, upon the relation of the cost of grinding to the loss of nutritive material from not grinding. If the miller's toll amounts to one-tenth the value of the grain the economy of grinding it may be doubtful, especially with ruminants. EFFECT OF COMMON SALT It is the custom of many feeders to allow their ani- mals an unlimited supply of salt, and others furnish it 134 • The Feeding of Animals in definite and regular quantities. The belief prevails more or less widely that an abundant consumption of salt is beneficial. If this is true, the advantage arises for other reasons than an increased digestibility. The verdict from earlier experiments by Grouveu, Hofmeis- ter and Weiske that the addition of salt to the ration does not increase the digestibility has been confirmed by more recent tests by Wolff. Indeed, if we give to the data collected a literal and perfectly justifiable in- terpretation, salt diminished rather than raised the proportion of digestible nutrients. INFLUENCE OP FREQUENCY OF FEEDING AND WATERING ANIMALS Few experiments relative to this point are on rec- ord. One by Weiske and others, relative to frequency of feeding, and another by Gabriel and Weiske, in which the effects of the time of watering and of the amount of water were tested, give no indication that the completeness of digestion is materially affected by variations in these details of practice. It seems proba- ble that the nutritive importance of these minor points in managing animals has been much overestimated by some, especially as affecting the utilization of the food. INFLUENCE OF CERTAIN OTHER CONDITIONS " It is well known that the composition of fodder crops grown on the same soil may vary somewhat from year to year according as the season is wet or dry, cold Combination of Nutrients 135 or warm. Such variations may influence digestibility, though no actual demonstration of this fact appears to be on record. The question is often asked whether the storage of hay for a long period affects its nutritive value. The data from four series of experiments touching on this point indicate that there is a per- ceptible, though not marked, decrease in digestibility of hay during long -continued storage. INFLUENCE OF THE COMBINATION OF FOOD NUTRIENTS Among the apparently important and freely ex- ploited conclusions drawn from investigations in ani- mal nutrition is the statement that the digestibility of food is influenced to a marked degree by the relative proportions of the several classes of nutrients. It is taught that if more than a certain percentage of starch and sugar, or of feeding stuffs rich in carbohydrates, like potatoes or roots, is added to a basal ration, the digestibility of the latter is decreased, the protein and fiber being especially affected. The conclusions, as stated by Dietrich and Konig, on the basis of a criti- cal study of the data involved are that if pure carbo- hydrates are used to the extent of more than 10 per cent of the dry substance of a basal ration, or if pota- toes and roots are fed equivalent in dry matter to more than 15 per cent, a depression of digestibility occurs, which increases with the amount of carbo- hydrate material added. A modifying conclusion is, that if the addition of the carbohydrate material is accompanied by correspondingly more protein, the de- 136 . The Feeding of Animals pressiou of the digestion coefficients is much lessened or does not occur. Many data are cited in support of these generalizations which are worthy of careful con- sideration. It is not unreasonable to suppose that the relative quantity in a ration of the several classes of nutrients may have an influence upon the digestive processes, and we should accept the verdict of previous observa- tions in so far as they will bear critical discussion and further investigation. It should be said in the first place, by way of comment, that the carbohydrate ma- terial in the experiments cited has usually been fed in addition to a basal ration, thus increasing the amount of food consumed, and, as we have seen, this may have an influence upon the proportion of total diy matter digested. In this particular, the experiments have not been logical. In the second place, in these experiments, no allow- ance has been made for the metabolic nitrogen in the feces, i. e., that not belonging to the true undigested residue. As this appears to be independent of the amount of protein fed and stands more nearly in rela- tion to the total digested nutrients, it follows that the smaller the proportion of protein in the digested food, the larger the error caused by the waste nitrogen products. A careful study of this point in the light of more recent knowledge might modify the conclusion reached as to the depression of protein digestion through feeding starch or starchy foods. In all or nearly all the experiments where this effect is appar- ently shown the digestible dry matter of the ration Digestion — Influence of Animal 137 was largely increased and the protein remained con- stant or was diminished. The depression of the di- gestibility of the crude fiber is not easily explained on any other ground than that of the influence of the greater proportion of starch. What is claimed as the effect of a dispropor- tionate addition to the supply of carbohydrates does not appear to be true of a similar increase in the ration of fat and easily digested protein. Several ex- periments in which oils and albuminoids have been added freely to a basal ration did not indicate that such addition had any material effect upon digesti- bility. CONDITIONS PERTAINING TO THE ANIMAL: SPECIES, BREED, AGE, AND INDIVIDUALITY The conclusion reached by the early experimenters in the field of animal nutrition that the digestive effi- ciency of the several species of ruminants was prac- tically uniform, has not been set aside by more recent observations. The number of experiments upon which this conclusion was based was large, and their verdict is not likely to be reversed by observations less ex- tensive or less complete. The following coefficients were obtained from Ger- man trials with meadow hay: Dry substance digested from meadow hay (per cent) Samples Best Medium Poor Sheep 42 67 61 55 Oxen 10 67 64 56 Horse 18 58 50 46 138 The Feeding of Animals Nine American experiments have been the means of studying results with large and small ruminants, steers being compared with sheep and cows with goats. In five cases, the large animal digested from 5 to 14 per cent the more, in three cases the excess for the small animal varied between 7 and 17 per cent, and in one case there was little difference. The general effect of such conflicting results is to confirm the older and more numerous observations. The horse and ruminants differ in digestive ca- pacity to a marked extent. The comparisons which have been made show a uniformly lower digestive effi- ciency for coarse fodders on the part of the former. It appears that because of less perfect mastication, or for some other reason, the horse dissolves much less of the crude fiber than the steer or sheep, and the effect of this is prominent with hays and other fibrous materials. With the grains, ruminant and equine diges- tion are not greatly unlike, eight samples of oats with sheep and twenty -four with the horse showing almost identical digestion of the dry matter. With maize the case is the same. In experiments with beans, the ad- vantage was slightly with the ruminant. So far as we are able to judge, swine digest concentrated food about as do ruminants and the horse. How this is in the case of the fodders we do not know fully, but it is proven that the swine digest crude fiber quite freely. Past experiments have not revealed any influence of breed upon digestive capacity. There is no reason for supposing that Shorthorn cattle, Southdown sheep and Digestibility — How Determined 139 Chester White pigs would digest rations differently from Jerseys, Merinoes and Yorkshires. Young animals seem to digest high quality coarse foods and grains as efficiently as older ones of the same species, which is probably contrary to the popular belief. There is doubtless a variation in the digestive power of individual animals, but the data so far collected do not show this with any degree of definiteness. In those in- stances where the same four or more steers or sheep have been used in determining the digestibility of sev- eral feeding stuffs the highest coefficients were obtained sometimes with one animal and sometimes with another. DETERMINATION OF DIGESTIBILITY If we accept as the undigested food the dry matter of the solid excrement, which is practically in accor- dance with the fact, we have only to subtract this fecal residue from the dry matter of the ingested food in order to ascertain the amount and proportion digested. All digestion experiments have proceeded on this basis. Animals have been fed at regular intervals a uniform quantity of carefully analyzed food and the feces have been collected, weighed and analyzed. From the data thus obtained, the digestion coefficients have been cal- culated. The method and the mathematics of such experiments are so simple that correct results seem very easy to obtain and they do possess an accuracy suffi- ciently approximate to truth to render them useful in practice. As digestion trials are usually conducted, the coefficients of digestibility obtained for the dry matter 140 The Feeding of Animals and total organic matter represent, we have reason to believe, very nearly the actual digestible matter in the particular material studied. The proportions secured for particular classes of nutrients may be less accurate, for reasons that will appear. We cannot be sure, either, that the digestibility of one hay applies to another produced and cured under totally different conditions. The truth of this latter statement is clearly seen in the effect of the various factors upon digestibility. The inaccuracies of digestion coefficients are chiefly in those for protein and fats. Let us see how and why this is. The errors in the figures for protein are caused by the presence in the feces of nitrogen compounds which are not a part of the undigested food protein. These are waste compounds which are residues from the bile and other digestive juices, epithelial cells and mucus which are carried along from the walls of the intestines during the passage of the food. Their quantity seems not to be proportional to the protein fed, but appears to be influenced more or less by the amount of food digested. Their source is the "wear and tear" of the digestive apparatus. It follows then that the less pro- tein there is in a ration, the larger the percentage error caused by these metabolic products. In certain experi- ments with oat straw, the fecal nitrogen has been more than that of I he food, although without question much of the straw protein was digested. It has been found, using the best methods known for extracting these waste products, that they cause a much larger error for the protein of the straws than for that of the legume hays. It is probably safe to affirm that at least ten should Digestibility — How Determined 141 be added to the coefficients of digestibility of the pro- tein of coarse fodders as usually given in the tables that have been compiled. Errors are caused in determination of the digesti- bility of fat in much the same way. Certain of the bile residues in the solid excrement are soluble in the ether which is used to extract the fats, and consequently the undigested fat appears to be larger than it really is. CHAPTER X THE DISTRIBUTION AND USE OF THE DIGESTED FOOD The digested food, after absorption, all passes into the blood, either directly or indirectly, and mixes with it. The materials which are to serve the purposes of nutrition are now taken up by a stream of liquid that is in constant motion throughout the minutest divisions of every part of the animal. Flowing in regular chan- nels the blood reaches not only the bones and muscular tissues, but it passes through several special organs and glands where the nutrients it is carrying and certain of its own constituents meet with profound changes. It is here that we discover the manner in which food is applied to use and what are some of the transforma- tions which the proteids, carbohydrates and fats under- go in performing their functions. In order to follow intelligently this most interesting phase of nutrition, we must know something of the blood and of the organs — the lungs, liver and kidneys — through which it passes. THE BLOOD The blood, when in a fresh state, is apparently colored and opaque, but if a minute portion is ex- (142) Blood and its Functions 143 amined with a microscope, it is seen to be a compar- atively clear liquid in which float numerous reddish, disk - like bodies. These bodies, which are known as corpuscles, give to the blood its bright red color. The liquid in which they are suspended is called the plasma. The corpuscles are not mere masses of unformed matter, but they are minute bodies having a definite form and structure. They make up from 35 to 40 per cent of the blood, and contain over 30 per cent of dry matter. This dr}~ matter consists mostly of haemo- globin, a compound that is peculiar to the blood and equips it for one of its most important offices. Haemo- globin, as before stated, is made up of a proteid (globin) and a coloring matter (haematin), in the latter of which is combined a definite proportion of iron. The peculiar property of this compound, which renders it so useful a constituent of the blood, is its power of taking up oxygen and holding it in a loose combination until it is needed for use. When thus charged, it is known as oxyhemoglobin. Because of this function of their most prominent constituent, blood corpuscles become the carriers of oxygen to all parts of the body. There are reasons for believing that they are also chiefly con- cerned in gathering up one of the waste products of the nutritive changes, viz., carbon dioxid, and convey- ing it to the points where it may be thrown off from the body. The plasma is about nine-tenths water, so that it easily holds in solution whatever soluble nutrients are discharged into it from the alimentary canal. Among 144 The Feeding of Animals its constituents are found members of all the classes of compounds that are important in this connection, — ash, protein, carbohydrates and fats. The proportion of ash is about 1 per cent, three-fourths of it being common salt, and the remainder consisting of phos- phoric acid, lime and other important mineral com- pounds. The solid matter of the plasma is rich in albuminoids, including the fibrinogen which is the mother substance of fibrin and several albumins and globulins. These proteids make up about 80 per cent of the total dry substance of plasma. Sugar and fats are also present, their proportions varying with the extent to which they are being absorbed from the digestion of food. It is evident that the blood is charged with those materials which we recognize as necessary to the construction and maintenance of the animal body. THE HEART In quantity, the blood is from 3 to 4 per cent of the total weight of the live animal. It is contained in the heart and in two sets of vessels, one set called the arteries leading from the heart by various ramifications to all parts of the body, and the other set called the veins, leading from all parts of the body back to the heart. Through these vessels the blood is moving in a constant stream, which we call the circulation. It does not move of itself, but is forced along by a very powerful pump, the heart. This is a highly muscular organ divided into four chambers, which are separated by valves and partitions, the two upper chambers be- Work of the Heart 145 ing called the right and left auricles, and the two lower the right and left ventricles. The right auricle is above the right ventricle and is separated from it by a valve, and the same is true of the left auricle and ventricle. Out of the left ventricle the blood is pumped into the arteries and after reaching the arte- rial capillaries throughout the entire body, it passes from these into the smallest divisions of the veins and comes back to the heart along the venous system, en- tering the right auricle. It is then carried to the lungs by way of the right ventricle and is returned to the left auricle to be sent to the left ventricle, and from there to again start on its journey through the body. The principal facts pertaining to the blood and its circulation have been reviewed in this simple man- ner as an aid to the discussing of other considerations somewhat pertinent to our subject. The nutrients, as prepared for use by digestion, enter the blood on its return flow to the heart, com- ing into the venous cavity by way of the hepatic (liver) vein and the thoracic duct as previously de- scribed. When, therefore, the right side of the heart is reached, a new accession of food material is on its way to sustain the various functions of nutrition. We are more interested in the object of blood cir- culation than we are in its mechanism. Somehow the digested food disappears into these constantly moving blood currents, and the only evidence of its effect which comes to us from ordinary observation is the warmth, motion and perhaps growth of the animal that is nourished. 146 The Feeding of Animals THE LUNGS The first point where important changes occur is the lungs. Here the blood loses the purplish hue which it always has after being used in the body tissues and takes on a bright scarlet, a phenomenon that is more easily understood when we understand the lung structure. Breathing is a matter of common experience. We all know how air is drawn into the lungs at regular intervals, an equivalent quantity being as regularly forced out. The mechanism of respiration (breathing) we will not discuss at length. It will aid us, however, if we know that the passage which the air follows to and from the lungs, the trachea (windpipe), divides into two branches, one to each lung, and these divide and sub- divide until thejr branch into numerous fine tubes. Each of these tubes ends in an elongated dilation which is made up of air cells opening into a common cavity. These cells are so numerous in the lung tissues that only a very thin wall separates adjoining ones, and in this wall are carried the capillaries or fine divisions of the blood-vessels leading from the heart. This arrange- ment permits the blood to take up oxygen as it flows along and transfer certain wastes into the lung cavities, and thus be made ready to go back to the body carry- ing a joint load of digested food and oxygen. Of course the air that passes out of the lungs is less rich in oxygen than when it was taken in, and there have been added to it certain materials which we will notice later. Changes of Food in the Tissues 147 THE USE OF FOOD The revivified blood now passes to all parts of the body and is brought into the most intimate relation with the minutest portion of every tissue. Several things happen in the course of time. In the first place, the new supply of nutritive sub- stances is used by the living cells in a way we do not wholly understand to rebuild worn-out tissue and to form new growth. With the young animal, much material is appropriated in the latter way. In the case of the milch cow, there is furnished to the udder the nutrients out of which the milk is formed through the special activities of that gland. Moreover, it is in the tissues that the oxygen which was taken up in the lungs is used to slowly burn a por- tion of the food. This combustion is believed not to take place by contact of the oxygen and food in the large blood-vessels, but it occurs by progressive steps throughout the minute divisions of the muscles and other parts of the whole body. Notwithstanding this oxidation may be very gradual and occupy much time, its ultimate products are, for the most part, similar to those which result from the rapid combustion of fuel. In the fireplace, starch, sugar, cellulose, fats and similar bodies would be burned to carbonic acid and water, and this is what takes place in the animal to the extent these nutrients are not used for growth. When the protein is not stored as such but is broken up, the result differs somewhat in the furnace and in the animal because in the latter the oxidation is not 148 The Feeding of Animals complete. Here the proteids may be partially burned to carbonic acid and water, but a portion of their sub- stances passes from the body principally in the form of urea and uric acid, which are the prominent constituents of urine. These compounds carry with them a certain proportion of carbon and hydrogen which in ordinary fuel combustion would more fully unite with oxygen. The heat production from protein is therefore less in the animal than in the furnace. This oxidation in the animal is constant but not uniform. It varies with the exercise the animal is tak- ing and with the amount of food that must be disposed of. The quantity of oxygen needed is therefore vari- able, and when the demand for it is largely increased the heart pumps faster, more blood passes through the lungs, the breathing is more rapid and the supply of oxygen is in this way augmented. ELIMINATION OF WASTES The various waste products from this combustion and from the breaking up of the proteids within the animal evidently must be disposed of in some manner. If not eliminated from the body, they would cause re- sults of a most serious character, as, for instance, when an accumulation of urea in the body produces uraemic poisoning. The blood therefore not only carries to the tissues the necessary nutrients and oxygen, but it has laid upon it the burden of taking into its cur- rents the waste products of combustion and growth and carrying them to the points where they are thrown off. Disposition of the Wastes 149 One of the branches of the arterial system of blood- vessels runs to the kidneys, and, by repeatedly rebranch- ing, traverses all their substance. The main function of the kidneys is to secrete the urine, a liquid in which all the waste nitrogen from the digested protein finds its way out of the body in the form of urea and similar bodies. The blood that enters them carries with it the urea and uric acid which have resulted from a break- ing down of protein, and in a most wonderful manner these compounds are filtered out so that they are not present in the outgoing blood. An excess of soluble mineral matters such as common salt is also removed by the kidneys, as well as the bile compounds which are absorbed from the alimentary canal. The carbon dioxid must in some way also be elimi- nated from the body. This is not accomplished to any extent until the blood containing it reaches the lungs, where it is exchanged for a new supply of oxygen and passes off in the expired air. In the case of man, the air "breathed out" is nearly a hundred times richer in carbonic acid than the air "breathed in." Water may be regarded from one point of view as a waste, for it is produced in the oxidation of the food, and this passes off from the lungs as vapor, through the skin as sensible or insensible perspiration, and in considerable quantities through the kidneys. To summarize, it may be said that the blood is con- stantly undergoing gain and loss. The gain comes from the food (including water and oxygen), and the loss consists of urea, carbonic acid and water given off through various channels. 150 The Feeding of Animals THE LIVER One part of the arterial system of blood-vessels runs to the stomach and intestines and is distributed over their walls in fine divisions. These connect with the capillaries of the portal vein which leads to the liver. During this passage of the blood from one system to the other, it takes up digested food, chiefly sugar. Now it is very evident that the quan- tity of material thus absorbed must varj^ greatly at different times according to the nature and amount of food supply and the activity of the digestive processes. If, therefore, the blood from the alimentary canal was allowed to pass directly into the general circulation, the* supply to the tissues of the nutrients, especially the carbohydrates, would be very uneven. Just here comes in a liver function. In that organ there is found a starch -like body known as glycogen, which appears in increased quantity following the abundant absorption of sugar from the intestines. It is believed, because of this and other facts, that the liver acts as a regulator of the carbohydrate supply to the general tissues of the body, storing a temporary excess of the sugar in the form of glycogen and then gradually giving it up to the general circulation as it is needed. CHAPTER XI TEE FUNCTIONS OF THE NUTRIENTS The digestion, absorption and distribution of food are not its use, — they are the preliminaries necessary to use. Not until the nutrients have been converted to available forms and have passed into the blood do they in the slightest degree furnish energy or building material to the animal organism. We have followed to a certain extent the chemical changes which the digested food suffers, but no detailed statements have been made as to the part taken by each class of nutri- ents in constructing the animal body and in maintain- ing its complex activities. Animals use food in two general ways; viz., for constructive purposes, which involve the building or repair of tissue and the formation of milk, and as fuel for supplying different forms of energy, including heat. The tissues which are to be formed are of sev- eral kinds, principally the mineral portion of the bone, the nitrogenous tissue of the muscles, tendons, skin, hair, horn and various organs and membranes, and the deposits of fat which are quite generally distributed throughout the body substance. Energy in the forms in which it is used by the ani- mal organism may appear as muscular activity, such as (151) 152 . The Feeding of Animals working, walking, breathing, the beating of the heart, the movements of the stomach and intestines, as heat, and as chemical energy necessary for carrying on di- gestion and other metabolic changes. The animal body is certainly the seat of greatly varied and complex constructive and destructive activities, which are sus- tained by the matter and potential energy of the food. How this is done we do not fully understand, but we know many facts which are of great scientific and prac- tical importance and which the feeder must consciously or unconsciously recognize if he would not come into conflict with immutable laws. FUNCTIONS OF THE MINERAL COMPOUNDS OF THE FOOD We have learned that mineral compounds are abun- dant in the animal body. The tissues, the blood, di- gestive fluids and especially the bony framework con- tain a variety of these bodies, which are as essential as any other substances to the building and mainte- nance of the animal organism. Bone formation with- out phosphoric acid and lime is not possible, and to deprive the digestive juices of the chlorine and sochi which they contain would be to destroy their useful- ness. Young animals fail to develop if given no mineral food, and mature animals when entirely "de- prived of even one substance, common salt, become weak, inactive and finally die. Not only must the growing calf have the ash compounds for constructive purposes, but the mature ox must be supplied with Uses of Mineral Compounds — Protein 153 them in order to sustain the nutritive functions. It is especially true of milch cows, which store combinations of phosphoric acid, lime and potash so abundantly in the milk that they must have an adequate supply of these substances. Nothing is clearer than that these materials must of necessity be furnished in the food. They cannot originate in the animal, neither can car- bon compounds take their place. Nature seems to have made generous provision for the animals' needs along this line. All of our home -raised feeding stuffs, as usually fed, contain in variet3 r and quantity all that is needful of these nu- trients except for poultry perhaps. Milk, that is the exclusive food of very young animals, is especially cal- culated to sustain the rapid bone formation which is taking place. It is only when feeding is one-sided, as in an exclusive corn diet, or when parts of a grain are removed, that we need fear a deficiency of 'the neces- sary mineral compounds. FUNCTIONS OF PROTEIN While there are at present many unsolved problems relative to the nutritive offices of protein, there is no reasonable doubt that the vegetable proteids are the only sources of similar substances in the animal body. This is equivalent to a statement that from the pro- teids are formed the muscles, the connective tissues, the skin, hair, horn, and hoofs, and the major part of the tissues of the secretive and excretive organs; in short, that they are the source of a large proportion 154 The Feeding of Animals of all the working parts of the animal's body. So far, scientific research has not succeeded in demon- strating that an albuminoid is ever synthesized (built up from simple compounds) outside of the plant. It appears that bodies of this class must come to animal life fully elaborated. This is a truth of great sig- nificance even in its relation to the nutrition of farm animals. The nitrogenous tissues are those that largely determine the vigor and quality of any animal, and as these are formed rapidly in the early stages of growth, a normal and unrestricted development demands an abundant supply of proteid food. It is also true of mature animals that sufficient protein is not only nec- essary to health and vigor, but it is essential to pro- duction that is satisfactory in quantity 7 and quality. The functions of protein are not restricted, how- ever, to the use already described. According to ex- isting views, it is utilized in more ways than any other class of nutrients. It was held at one time by prominent scientists that outside the vegetable fats it is the sole source of animal fats, and this view was, not so very long ago, to some extent accepted. Indis- putable proof to the contrary is now in our possession, and some investigators even go so far as to deny the possibility of the formation of fat from protein. On this point, opinion is divided. Certainly we must be convinced that nitrogen compounds of the food are, with some species, not the most important source of animal fat, for various investigators, such as Lawes and Gilbert, Soxhlet, and others, have shown upon the basis of searching experiments that sometimes over Uses of Carbohydrates 155 four -fifths of the fat stored by pigs must have had its origin outside the food protein and fat. Besides all this, the common experience of feeders that foods highly non -nitrogenous are often the most efficient for fattening purposes is good common -sense evidence that fat formation is not greatly dependent upon the pro- tein supply. Nevertheless, the possibility of producing animal fat from protein is not disproved, and there are several considerations which make it seem probable that under certain conditions this does occur. Protein can unquestionably serve as fuel, or, in other words, as a source of energy. The amount so used depends much upon the animal fed and the character of the ration. In the case of a. dog eating an exclusive meat diet or of a fattening animal which receives a ration liberally nitrogenous, probably the greater part of the protein eaten is not stored but is used as fuel. With milch cows or young animals growing vigor- ously, a much larger proportion escapes oxidation. The fuel value of protein will be discussed later under another head. FUNCTIONS OF CARBOHYDRATES Carbohydrates are usually characterized as the fuel portion of the food, or that part which is burned to produce the various forms of energy. This conception of the function of these bodies is correct in the sense that in the case of ruminants they constitute the larger part of the fuel, although not the whole of it. For instance, in the case of a cow eating daily sixteen 156 . The Feeding of Animals pounds of digestible organic matter, giving thirty pounds of milk containing 15 per cent of solids, and neither gaining nor losing flesh, not far from five pounds of this organic matter would he found in the milk and urine, leaving about eleven pounds to be used as fuel, about a pound and a half of which might be derived from the protein and fat, the remainder, or 9.5 pounds, consisting of carbo- hydrates. If a fattening steer were eating the same amount of the same kind of food and gaining two pounds of live weight daily, the body increase and urine would contain not over 2.5 pounds of dry matter, leaving not less than 13.5 pounds to be oxi- dized, of which twelve pounds might consist of car- bohydrates and fat, mostly the former. It is clear, then, that while other bodies serve as fuel, the carbo- hydrates furnish much the larger part of that which is needed for this use. Contrary to views that held for a time, it is now well established that the animal fats may have their source in the carbohydrates ; in other words, starch and sugar and related bodies may serve the main purpose in feeding animals for fattening. In many experiments, notably those with swine, the protein and fat of the food have fallen far short of ac- counting for the fat in the body increase, some- times much the greater part of the latter having no possible source other than the carbohydrates. A practical expression of this general conclusion con- cerning the fat -forming function of carbohydrates is seen in the well -recognized value of corn meal as a Uses of the Fats — Energy 157 fattening food, a feeding stuff nearly seven -tenths of which consists of starch and its allies. Recent experi- ments with milch cows leave scarcely any doubt that milk fat may also be derived from carbohydrates. These more recent views tend to magnify the impor- tance of the carbohydrates as nutrients. FUNCTIONS OF THE FATS AND OILS So far as is at present known, the possible uses of the food fats and oils and of the carbohydrates are sim- ilar. In other words, both may serve as fuel and both may be a source of animal fat. The differences are that the supply of carbohydrates is much the larger, and the fuel value of a unit weight of fats much the greater. Moreover, it seems possible for a vegetable fat to be- come deposited in the animal without essential change, whereas fat formation from carbohydrates involves complex chemical transformations. FOOD AS A SOURCE OF ENERGY The living animal, either as a whole or in some of its parts, is constantly in motion. This means that the animal mechanism is ceaselessly performing work. Even if the body is apparently quiet, the heart beats, pumping blood to all parts of the body, the lungs are expanded and contracted, and the stomach and intes- tines keep up the movements which are essential to digestion. Besides, a living body is the seat of con- tinuous, invisible and complex chemical and physical changes that, if not work in the common meaning of 158 The Feeding of Animals the term, are its equivalent. Walking, trotting, pull- ing, lifting, pumping blood, breathing, masticating, digesting and assimilating food represent, then, a great variety of operations of those living machines which we have named horse, ox, cow and sheep. Now work requires the expenditure of energy. The projection of a rifle ball through space at the rate of two thousand feet per second is work. The ball does not move of itself, but is propelled by the application of the energy stored in a powerful explosive. Back of every one of our great mechanical operations, such as pumping, grinding and moving railroad trains, will always be found some sort of energy, and what is true of machinery made of wood and iron is equally true of that made of bone and muscle. The fact that the mechanism is alive does not abrogate a single physical law, so that the fundamental principles of energy as applied to machines are as fully applicable to the activ- ities of animal life. It is safe to go farther, and say that the animal organism does not originate energy. Among the fun- damental conceptions upon which all our knowledge of chemical and physical laws rests is this, that energy and matter are indestructible, and, moreover, that the sum total of these in the universe is unchangeable. If, then, the horse expends the muscular energy neces- sary to draw a load of one ton over ten miles of road, the equivalent of this must have been supplied to his body from some outside source. He could not create it. We know that this is so, and we also know it is con- veyed to the animal in the food. Forms of Energy 159 This is a complex, but a fascinating, field of in- quiry; one that is now receiving much attention in our researches after a more intimate understanding of the facts and principles of nutrition. It will be profitable, therefore, for us to gain some conception of the knowl- edge of this kind, which so far seems to have a practical bearing upon our subject. It is natural to first ask, What is energy? This is a difficult question to answer in a popular way, and the physicists' definition would hardly serve our pur- pose. All we can do, perhaps, is to illustrate it by pointing out some of its manifestations. Let us re- sort to an old illustration. Every farmer's boy has doubtless seen a blacksmith hammer an iron rod un- til it was red hot. The motion of the hammer-head descending with great velocity was suddenly arrested when it came in contact with the rod. This descent of the hammer-head illustrated one form of active energy; viz., motion of a mass of matter. When the hammer met the iron rod on the anvil, the mass motion ceased. Was the energy therefore last? Not unless our fundamental conception is wrong, and we find that in this case it is not. The physicist teaches us that the motion of the hammer-head, a mass of matter, was communicated to the smallest par- ticles or molecules of the iron rod, and as the vibra- tions of the molecule increased in rapidity, the rod grew hotter and hotter. Here we have another illustra- tion of energy; viz., the motion of the molecule or heat. The iron rod might have been heated in another way, — by plunging it into burning charcoal. And from 160 The Feeding of Animals whence would the heat energy come in this case ? From the combustion of the carbon. Somehow, when it is deposited in the plant, there becomes stored in this carbon, in a way about which we can only theorize, what perhaps we may call the chemical energy of the atom, which, when combustion occurs, is changed into heat or molecule motion. From these phenomena we learn that not only are there several forms of energy, but that one form is transferable into another. Perhaps another illustration may still further serve our purpose. A small dynamo is being run by a pair of horses working in a tread power such as is used for threshing grain. The horses are constantly climb- ing up a moving treadway and thereby communicating motion to machinery. This motion is, by the dynamo, converted into electricity, which, by passing through the carbon film of an incandescent lamp and there meeting resistance, is in part, at least, transformed into heat. We have, then, in a chain, muscular effort, motion of the mass (pulleys, wheels, etc.), electricity and* heat, all active energy and all transferable the one into the other. This is a fairly good picture of what goes on with the horse himself, externally and internally, in sustaining life and performing labor for his owner. Back of it all, and this is what interests us, is the animal's food. As a result of years of patient investigation, it has become known that through the combustion of the carbon compounds of vegetable and animal origin, which serve as nutrients, chemical energy may be transformed into those other forms that are manifested in the activities of living Measurement of Energy 161 beings. When we ask from whence comes the energy given up by the plant compounds, we arrive at our last stage of inquiry. Here we enter the domain of plant life, and it is a notable triumph of the human intellect that we are able to declare with certainty that the ceaseless and multiple activities of life on this planet are sustained by an energy which comes to the plant in the sun's rays through almost limitless space. It is obvious that if the internal and external work performed by the animal are sustained by the food, it is desirable to measure the energy available in differ- ent feeding stuffs, provided, of course, that they differ in this respect, as we know they do. In order to measure anything, we must have a standard or unit of measurement. In this case it cannot be a unit of space or of mass, that is, we cannot declare that corn meal contains so many cubic feet or pounds of avail- able energy. Energy has neither dimensions nor weight. If we measure it at all, it must be by units of tem- perature or of work performed. Units of this kind are applied to the measurement of food energy. The one most commonly in use is the Calorie, this being the energy which in terms of heat is sufficient to raise the temperature of one pound of water 4° Fahren- heit. Expressed in terms of work, the Calorie is very nearly 1.53 foot tons, or in other words, it is equiv- alent to the work involved in lifting one ton 1.53 feet. Heat units are expressed in both the large Calorie and the small calorie. When the former is in- dicated, the word begins with a capital letter. The Calorie represents 1,000 calories. K 162 The Feeding of Animals The total energy or heat units developed in the combustion of feeding stuffs is determined in an ap- paratus called a calorimeter. The latest form of this device is one in which the ground hay is burned under pressure in the presence of pure oxygen, and the heat evolved is all used in warming a known weight of water. Data are thus obtained from which it is possi- ble to calculate the Calories in the particular material burned. The energy value of single compounds, such as albumin, starch and sugar, may also be found in the same way, as has been done in a large number of instances. These data show that the heat resulting from the combustion of the compounds of the same class is not the same in all cases. The value in large Calories of one gram (about one -twenty -eighth of an ounce) of the several nutrients is shown in the following table: Albuminoids, etc. Cal. Cal. Wheat gluten 5.99 Egg albumin 5.73 Gliadin 5.92 Muscle (pure) 5.72 Glutenin 5.88 Blood fibrin 5.64 Plant fibrin 5.94 Peptone 5.30 Serum albumin 5 . 92 Wool 5.51 Milk casein 5.86 Gelatin 5.27 Yolk of egg 5.84 Asparagin (amide) 3.45 Carbohydrates Cal Fats c j Starch 4.18 Of swine 9.38 Cellulose 4.18 Of oxen 9.38 Glucose 3.74 Of sheep 9.41 Cane sugar 3.95 Maize oil 9.28 Milk sugar 3.95 Olive oil 9.47 Maltose 3.95 Ether extract of oats. . . 8.93 Zylose 3.74 Ether extract of barley. 9.07 Available Energy 163 The heat values of a gram of the dry substance of various cattle foods, which is a mixture of the several nutrients, was found by recent determinations to be the following, expressed in small calories: cal. eal. Mixed hay 4494 Corn meal 4471 Alfalfa hay 4478 Linseed meal 5040 Oat straw 4480 Flaxseed meal 6935 Sugar beets 3931 Rice meal 4400 These figures mean that when a gram of each of these materials is wholly burned the heat produced is as stated. Available energy. — We must distinguish, however, between the heat produced when any food substance is wholly oxidized in a calorimeter and the heat or energy which is available when the same material is applied to physiological uses. It never happens that the combus- tible portion of a ration is entirely burned in the animal. In the first place, the food of domestic animals is practically never all digested and, as only the digested portion furnishes energy, the available fuel value of a ration must be based primarily, not upon the total quantity of dry matter it represents, but upon the amount which is dissolved and passes into the blood. If all feeding stuffs or rations were digested in the same proportion and with the same ease, their total fuel values might show their relative energy worth, but as digestion coefficients for dry matter vary from less than 50 per cent with the straws to nearly 90 per cent with some of the cereal products, it is evident that the fuel waste in the feces is not uniform. 164 The Feeding of Animals In the second place, the digested proteids are never fully burned. A portion of these compounds always passes off in the urine unoxidized, the fuel value of which is lost to the animal. For this reason the avail- able energy of the proteids is about one -fourth less than the total. In the third place, there is, with ruminants and horses at least, an escape from the alimentary canal of unconsumed gases, due to the fermentations which take place during digestion. These gases, mostly methane (marsh gas), have their source in the carbo- hydrates, and Kellner found them to represent from 10 to 20 per cent of the total energy value of the dry substance digested from various materials. From twenty experiments, upon five different animals, Kiihn found the loss in methane to be over one -seventh the energy of the digested crude fiber and nitrogen -free extract. We are to understand, then, that the available energy of a ration is represented by the fuel value of the dry matter which is digested from it, minus the dry matter of the urine and that lost in gases. If, however, we wish to know the actual energy gain to the animal from a particular ration, we must go farther than a determination of its available energy. Net energy. — Within a comparatively short time we have begun to speak of the net energy of foods, and as this is a practical consideration which is likely to be the subject of much future discussion, it is well to no- tice it in an explanatory way. As we have learned, food is not applied to use until it reaches the blood. Energy Loss in Work of Digestion 165 Between the time when it is taken into the mouth and when it passes into the circulation, it must have work expended on it in the way of mastication, solution and moving it along the digestive tract, and it appears highly probable that the amount of this work per pound of food must vary greatly in different cases. In fact, we know this is so from the result of some masterly investigations conducted by Zuntz in Ger- many. By means of various devices and methods, a description of which would be out of place here, he measured the oxygen consumption necessary to sustain the mechanical energy of mastication and digestion, and he calculates from his determinations that the fol- lowing heat units represented the energy used in chewing certain feeding stuffs: cal. eal. 1 pound hay 76 1 pound corn 6 % 1 pound oats 21 Green fodder equal to 1 pound of hay 47 The differences revealed by these figures are inter- esting and important. Chewing green food cost in labor only about 62 per cent of the effort required to masticate its equivalent of dry hay, the proportions of labor for hay, oats and corn being in the ratio of 100, 27 and 8%. This author goes further and calculates that the work of mastication and digestion combined is 48 per cent of the energy value of the digested mate- rial from hay and 19.7 per cent of that from oats. He also makes the statement that in general the coarse foods have 20 per cent less net energy value than the 166 . The Feeding of Animals grains. All these deductions are based upon the excess of oxygen used by the animal when engaged in the work of chewing and digestion, over that used when at rest. It follows from these results that anything in the way of growth or treatment of a fodder which tends to toughen or harden the tissue reduces the net energy value. It has long been believed, though perhaps not proved, that grain foods are superior to coarse foods to an extent not accounted for by the differences in digestibility, and if this is a fact, it is explained in part by the unlike com- position but is to some extent undoubtedly due to the greater effort of chewing and digesting the fodders. If we wish to ascertain the comparative energy worth of two unlike rations, it would obviously be incorrect to multiply the total quantities of protein, carbohydrates and fats in each by the unit heat values in order to ascertain the relative energy gain to the animal body. To recapitulate, we may define available energy as total energy minus that which is lost in the excreta and in gases which escape, and net energy as available energy minus the cost of digestion and of preparing the food for use. Net energy is the balance of profit to the animal. ENERGY RELATIONS OF THE SEVERAL NUTRIENTS As has been pointed out, the animal body is the field of numerous mechanical activities. What is the rela- tion of the several nutrients to these manifestations of vital energy is an interesting and in some ways an intensely practical matter. For instance, has protein a peculiar function in the maintenance of muscular Maintenance of Muscular Effort 167 activity which no other nutrients have f The belief prevailed at one time, that muscular contraction caused a wasting of the muscle substance which must be re- placed by the proteid compounds of the food; in other words, protein alone was believed to sustain the work of the animal body, both internal and external. It would folloAv from this that the more work is done the more protein is needed. This view is no longer held. The more exact methods of modern research have revealed the fact that an increase of muscular effort, even up to a severe point, increases but little, if any, the nitrogen compounds of the urine, these being the measure of the protein that is destroyed. There has come to light a corresponding fact that the consumption of fuel in the body other than proteids increases proportionately with the increase of work. This means that as animals are ordinarily fed mechanical work is largeh^ sustained through the combustion of carbohydrates and fats, and that while for reasons we do not yet wholly understand a fairly generous amount of protein seems to promote the well-being of a draft animal, the non- nitrogenous nutrients mostly supply the extra energy demanded for the labor. Heat relations. — The question is very naturally asked, As no energy is lost, into what is the energy of muscular contraction converted, as, for instance, that required for walking, the beating of the heart and the work of the intestines ? It is concluded by physiologists that muscular energy used by the animal is partly trans- formed into external motion and partly into heat, and this certainly is consistent with facts as observed. Vio- 168 The Feeding of Animals lent exercise by the animal greatly increases the produc- tion of heat. We know this is so because under these conditions an increased amount of blood is thrown to the surface of the body, thereby greatly increasing the loss of heat by radiation; perspiration sets in and with it the consequent evaporation of much more moisture, thus disposing of much heat. The dog, and sometimes other animals, pants and thereby causes a large loss of heat from the expanded surface of the moist tongue. All this occurs without reducing the body temperature below the normal. In fact, nature adopts these various devices, such as increased circulation of the blood and perspiration, in order to regulate the body temperature and prevent its rising above the proper point. The explanation of this greater heat during labor is that the mechanical energy manifested by the muscles is con- verted to heat, which under circumstances of severe exercise is more than enough to keep the body at its usual temperature and maintain the usual radiation. When it is severely cold, on the other hand, vigorous exercise is sometimes necessary in order to keep suffi- ciently warm. The view is held by some that all body heat is a secondary product, that combustion first supports mus- cular activity which changes to heat, in fact, that no food is burned primarily to keep the animal warm. Convincing proof of this position is still lacking, how- ever. There appears to be no good reason why we should deny the possibility of combustion of food for the specific purpose of warming the body. Certainly an Arctic climate causes a consumption of food which Heat Re (j illation 169 in kind and quantity would be impracticable in the tropics, and this too, even if there is no apparent in- crease of internal or external work. This would seem to indicate the direct oxidation of food for heating purposes. In any case, animal heat is sustained either directly or indirectly by the burning of the nutrients. CHAPTER XII PHYSIOLOGICAL VALUES OF THE NUTRIENTS The preceding discussion of the physiological uses of the various nutrients has dealt largely with them as classes. The special functions and relative values of individual compounds within the same class or of the different classes have not been considered. We know, for instance, that the albuminoids are in a general way flesh -formers, or fat -formers, or heat- formers, but we desire still further information as to the relative efficiency of the individual albuminoids for any specific purpose. Are some albuminoids more use- ful than others in aiding milk secretion ? Similar knowledge concerning the non-nitrogenous nutrients is important. How valuable physiologically is cellulose as compared with starch ? Again we are convinced that both the carbohy- drates and the vegetable fats may be sources of animal fats, but we are bound to inquire what is the relative importance of these groups of compounds as fat- formers in the animal body. It is easy to understand that knowledge of this kind would be valuable. We are coming to know a great deal about the composition of the various cattle foods, and if we could ascertain the exact physiologi- (170) Relative Energy and Production Values 171 cal uses and relative values of even the most promi- nent individual compounds, we would be able to make somewhat definite comparisons of the different feeding stuffs. It must be confessed that information of this specific kind is not as complete as one could wish. Its acquirement is very difficult and its present status is in some particulars unsatisfactory. Investigations so far conducted are not only insufficient to final con- clusions, but researches by different observers have re- sulted in a conflict of opinion in some cases. RELATIVE ENERGY AND PRODUCTION VALUES OF THE NUTRIENTS SINGLY AND AS CLASSES It is satisfactorily established, as we have seen, that protein, carbohydrates and fats have certain func- tions in common, that is, that all three classes are utilized as fuel, and that both carbohydrates and fats, and perhaps protein, may be a source of body fat. The question naturally arises, What is the relative value of these unlike nutrients as a source of energy and as fat-formers? Moreover, as each class is made up of a variety of substances, unlike in physical and chemical characteristics, can we consider the individual compounds within the same class as nutritively equal ? Relative energy values.— As a source of energy, the carbohydrates and their allies are properly regarded as of first, importance because of their large relative use as a fuel supply. These bodies, so far as they are digestible, have been considered in formulating rations as of practically equal value. It is well known that 172 The Feeding of Animals this is a doubtful assumption. The nitrogen-free ex- tract digested from the fodders is much more largely derived from crude fiber and the gums than that di- gested from the grains, starch being predominant in the latter, and we are not justified in concluding, except from reliable evidence, that the materials from the two sources are similar and equivalent as nutrients; in fact, some investigators believe the reverse to be true. If we accept the heat of combustion of the carbo- hydrates and similar substances when burned in a cal- orimeter as the measure of their energy value, we have definite figures. The heats of combustion of the com- pounds found in the nitrogen-free extract have been found to vary from 3.7 to 4.2 Calories per gram. This indicates no great difference in value for the production of heat energy. We are not sure, how- ever, that what is true of simple, rapid combustion is true of physiological use. Certain related facts must be considered. Because of Tappeiner's conclusion that the fermentations to which cellulose is subject, break it up mostly into gases and organic acids which he regarded as largely not useful to the animal, the view has more or less prevailed that digested crude fiber is greatly inferior to starch as a nutrient. More recent investigations throw doubt upon the correctness of this view, and the trend of opinion now seems to~ be towards regarding cellulose as taking practically the same place in nutrition, apart from ease of digestion, that starch does. It appears that the fermentations in the digestive tract of starch, sugar and other carbo- Value of the Nutrients 173 hydrates also give rise to gases which pass off uncon- sumed, though perhaps not to the same extent as is the case with crude fiber, and several observers de- clare that digested crude fiber is no less nutritively efficient in a maintenance ration than the more soluble compounds of the nitrogen -free extract. The question has been raised as to whether the gums (pentosans) which exist so abundantly in many coarse foods and in some grain products, like wheat bran, are not inferior to the other more soluble carbo- hydrates. It has been observed that the sugars which result from the action of ferments on these bodies have, in some instances, not been oxidized, but have passed off in the urine as such. It appears doubtful whether under normal and usual conditions this occurs to any extent. The gums are constantly present in all rations for farm animals, and we have no reason for believing that the pentose (gum) sugars are constant ingredients of their urine. The comparative physiological values of individual albuminoids and fats we do not know very much about, other than what we may judge from the determinations of heats of combustion. In experimental work single compounds have been but little studied. The conclu- sions reached have usually been based upon the results of feeding mixtures of individual albuminoids and fats as they ordinarily exist in plants. Determinations of the heats of combustion of single and mixed albuminoids and fats from various sources show a variation of from 5.6 to 6 Cal. per gram for the former and from 9.2 to 9.6 Cal. for the latter. The 174 The Feeding of Animals variation for the same class is seen not to be large, but whether the animal derives energy in similar propor- tions must be decided by experimental evidence. In recent years much attention has been given ex- perimentally to the physiological values of the nutrients. Among the most painstaking and extensive investiga- tions of this sort are those conducted at Mockern by Kellner and his associates. This work includes forty- four metabolism experiments, each of fourteen days' duration, and one hundred and eighty -four respiration experiments, each of twenty -four hours' duration. In order to secure the desired data, there was added to a basal ration gluten, oil, potato starch, extracted straw (mostly cellulose freed from incrusting and accom- panying compounds), meadow hay, oat straw, and well- ripened wheat straw. From the results obtained, through exact measurements of the ingested food, the excreta and the products of respiration, — thus making it possible to determine the relation of each substance to the maintenance of the animal and to the storage of flesh and fat, — Kellner worked out both the energy and the production values of the experimental materials. While the figures given should not be regarded as final, they have behind them so much careful and severe investigation that they must be accepted as having great weight. They at least correctly record what happened with particular animals. In presenting these results a distinction is made between available energj* value and production or net value. It is the former which interests us at this point, and it is this which is shown in the following figures: Available Energy in Typical Nutrients 175 Total heat value Per cent of Available heat Comparative of 1 gram of loss in urine value for 1 gram available heat digested and gases- digested value when organic matter methane organic matter starch is 100 cal. Percent cal. Starch 4183 10.lt 3760 100 Extracted straw.. 4247 14. t 3651 97 Molasses 4075 10.4 3645 97 Meadow hay 4480 18.7 3640 97 Oat straw 4513 16.9 3747 100 Wheat straw 4470 25.6 3327 88 Gluten 6148 19.3tt 4958 132 Peanut oil 8821 8821 235 t Loss wholly from methane. tt Loss wholly in urine. The available energy is seen in the total energy of the digested organic matter less that which is lost in the nrine and from fermentations which produce the gas -methane. These figures show the energy or heat furnished to the animal by the different materials after deducting losses. They also represent the heat production when the substances were fed in a maintenance ration, and as Rubner has demonstrated that the heat lost from the animal that is eating just a maintenance ration is a measure of the animal's use of food, these values show what the different substances were worth for maintenance purposes. It appears that in these investigations the sugars of molasses, ex- tracted cellulose and the material digested from the coarse foods containg much cellulose and gums sup- plied practically the same available energy to the animal that starch did, wheat straw excepted. Relative production values of the different nutrients. — If we calculate the fat -forming value of protein and 176 The Feeding of Animals starch on a purely theoretical basis as Henneberg did some years ago, it would appear that 100 parts of body fat can be obtained from 194 parts of albuminoids or 244 parts of starch. The fat factor of albuminoids would be therefore 51.4% and of starch 41%. The equivalence of food fat in terms of body fat has never been expressed on such a basis, though it is customary to assume that the fat of the food may cause the pro- duction of an equal quantity of body fat or milk fat, an assumption which has no foundation whatever. These theoretical figures are an attempt to show what protein and starch may do when actually used for storage purposes. They cannot be accepted as meaning much in indicating how the food is really used in practice. It is probable that the excess of food over and above maintenance is never all used for production according to the theoretical possibilities based upon chemical rearrangements of compounds. Certainly the production from a given quantity of food varies greatly under unlike conditions. It can scarcely be doubted that the proportion of the avail- able nutrients which are consumed, that is, burned as fuel, increases as the ration increases above what is needed for maintenance, and inversely the proportion of the nutrients stored, in the body as flesh and fat is less the greater is the quantity fed in excess of the demands for maintenance. A large excess over maintenance is relatively less efficient than a small one. There comes a point where additional food pro- duces no additional gain, but only additional consump- tion. The age of the growing animal and the condition Productive Value of Typical Nutrients 177 of a fattening animal also modify the efficiency of the food for production purposes, as does the period of lac- tation with a cow. With all these variations we have no averages which express with any definiteness the relative practical production value of the different nu- trients. Nevertheless this question has been the sub- ject of severe and extended investigation, and some of the results have given valuable information. Henneberg and Pfeiffer estimate that in experiments with sheep the protein in excess of maintenance caused the production of from 30.7 to 41.1 parts of fat for each 100 parts of protein. It is not shown that the fat came directly from the protein or from the carbo- hydrates which the excess of protein replaced in other uses. Experiments by Kiihn are made the basis of the conclusion that 1 pound of starch supported the storage of .2 pounds of fat. The most reliable and extensive data as to pro- ductive values are those already referred to as having been reached by Kellner and others at Mockern. They are summarized in the following table: Heat Mainten- Percentage Productive Compara- value anee value Mainten- value tive grain grata ance value gram productive organic organic applied to organic value, matter matter production matter starch 100 cal. eal. Per cent cal. Starch 4183 37G0 58.9 2215 100 Extracted straw... 4247 3651 63.1 2304 104 Molasses. 4075 3645 63.6 2310 104 Meadow hay 4480 3640 41.5 1512 68 Oat straw 4513 3747 37.6 1409 64 Wheat straw 4470 3327 17.8 592 27 Gluten 6148 4958 45.2 2241 101 Peanut oil .. 8821 8821 56.3 49t!6 224 L 178 The Feeding of Animals The productive value is stated in terms of the available energy less (1) the energy devoted to the work of chewing and digestion, and (2) that which is appropriated to the molecular rearrangement of the di- gested compounds which are transferred to the body substance. These being the factors which diminish productive value, it is easy to understand how the usefulness of a nutrient is somewhat determined by its source. When it is contained in a coarse fodder like straw where the work of chewing aud digestion is large and where, because of its physical condition, the fodder is slowly acted upon by the digestive fluids and is thus subject for a long time to the action of micro-organisms, the nutrient is less valuable than when supplied to the ani- mal in grain where the work of mastication, digestion and solution is a minimum. Starch, extracted straw and molasses, requiring no energy for mastication and but little for solution, supply digested material which Kellner found to be four times as valuable for pro- duction as that coming from ripe wheat straw The foregoing figures do not tell us how much a steer would gain daily when fed upon a certain quantity of these nutrients, but they do indicate in a general way what is the relative efficiency of the nutrients when derived from given sources. They give us a scientific explanation of the fact that coarse foods are not adapted to rapid production. Relative importance of the protein compounds. — Much prominence has been given to the fact that protein includes several groups of nitrogen compounds Differences in Protein Compounds 179 quite unlike in character. We know also that these groups exist in cattle foods in unlike proportions. For example, a much larger part of the protein of roots consists of amides than is the case with the grains, the protein of the latter being correspondingly richer in albuminoids. If, therefore, albuminoids and amides differ in function or value, we have established one point of unlikeness between cornmeal and turnips. The testimony so far obtained is quite consistent in one direction, and indicates that the flesh -forming function is confined to the true albuminoids. This means that gelatin, amides (asparagin, etc.), extrac- tives (creatin, etc.), cannot supply real muscle-build- ing material. These non-proteids have nutritive value, however. Experiments with gelatin and asparagin have led to the conclusion that their presence in the ration so protects the albuminoids from consumption that the latter may have their maximum use as flesh- and milk -formers. The extractives seem to have a peculiar place among the nutrients. They are not regarded as flesh -formers, or as fuel, but so far as is known they act merely as stimulants of the nervous system. The albuminoids are the only flesh -formers. There are, however, many albuminoids, and they differ among themselves as raw material out of which to construct the primary tissues of the animal body. Can albu- mins do what globulins cannot ? Are nucleins su- perior to albumins for special purposes % Not much that is definite can be said on this point. Because the various nitrogenous feeding stuffs are so generally 180 The Feeding of Animals interchangeable in the ration, without marked effect upon its efficiency when the protein supply is not diminished, it seems probable that the albuminoids are largely interchangeable in use. On the other hand, certain observed facts throw doubt on this view. For example, well-conducted experiments show that animal protein is superior to vegetable protein as food for ducks, when the two kinds are supplied in equally digestible quantities. It is possible that there are other differences in the effect of the protein from un- like sources which the ordinary methods of observation have not been competent to detect. One interesting question which has been consid- ered, is whether the special nuclein bodies (albu- minoids containing phosphorus) which are found so abundantly in eggs and in milk must be supplied as such in the food, or whether they may be built up in the animal from other albuminoids and phosphates. If we could learn that the food must contain these pe- culiar albuminoids all ready for use, then we would have a valuable suggestion for feeding cows and poultry. It now seems improbable that this is the case. The sea salmon, which, during its stay up the river, is believed to take no food, undoubtedly produces large masses of eggs from the body substance, and it seems unlikely that so much nuclein as is needed exists in the flesh. If a cow gives thirty pounds of milk daily, nearly or quite a pound of casein must come from somewhere, and there is no evidence that any ordinary ration would contain so large a quantity of phosphorized albuminoids. Hens' eggs are rich in nuclein, bej^ond Differences in Protein Compounds 181 any amount which the food seems likely to supply. Notwithstanding this indirect evidence, it cannot be safely affirmed that one albuminoid does not pos- sess much greater value for a specific purpose than another, and here is a field in which the investigator may render valuable service. CHAPTER XIII LAWS OF NUTRITION The preceding pages have been devoted to a discus- sion of the origin of cattle foods, what they are in substance, how their nutrients are made available and how used. So far no attempt has been made to gather together in a systematic relation what may be called the fundamental principles or laws of nutrition, some of which we have not yet directly stated, but which are inferences from the facts presented. It is desirable to do this, however, before passing to the consideration of the practice of cattle feeding. 1. All energy and building material applied to the maintenance and growth of the animal body come from the food, water and oxygen being included in this term. The animal originates neither force nor matter. 2. Only that portion of the food which is digested, i. e., that which is dissolved by the digestive fluids and rendered soluble and diffusible so that it passes into the blood, is available for any use whatever. This facu is especially important in view of the greatly varying digestibility of different feeding stuffs. 3. The unutilized food and the wastes pass from the body in some direction. The undigested part mainly (182) Laws of Nutrition 183 constitutes the solid excrement or feces. The urea and other nitrogenous compounds which are the unoxidized portion of the protein, pass out wholly in the urine. All digested nitrogen not stored is found here. The car- bon dioxid is eliminated through the skin and lungs, chiefly the latter, and water is disposed of through the kidneys, skin and lungs. 4. The digested food is used in two general direc- tions, (a) for the protection of energy and (6) for constructive purposes. (a) The food energy is made available through combustion, i. e., the burning of the carbon compounds of the food to simpler substances, carbon dioxid and water, thus liberating the energy stored in the plant during its growth. Protein is never fully oxidized, but carbohydrates and fats may be. All the organic nu- trients may be oxidized to produce energy, the total heat values of protein, carbohydrates and fats being approx- imately as 1.5, 1, 2.4. This liberated energy finds ex- pression in the animal organism in various ways, as heat, mechanical energy or motion and chemical transforma- tions. The total energy of food is never all available to the animal because of a loss in the excreta and gases. Moreover, the net energy gain seems not to be propor- tional to the available energy, but is dependent upon the work of digestion, which varies with different cattle foods. (b). The food compounds are used for constructive purposes, either without changing their general char- acter, as, for instance, the building of muscular tissue from the plant albuminoids, or they may be reorgan- ized into bodies of a very different character, as in the 184 The Feeding of Animals formation of animal fats from starch and sugar. Pro- tein is used to construct muscular tissue, in fact, all the nitrogenous parts, and it is perhaps a source of fat. Carbohydrates can only be used constructively for the formation of fat, and the same is true of food fats or oils. Mineral matter is needed for the forma- tion of bone and has important functions in digestion. 5. The matter of the digested food, including water and oxygen, is exactly equal to that stored in the body or in milk, or both, plus that in waste products, — feces, water, carbonic acid and urine solids. Such a balance may not be maintained for any particular day, but will ultimately be found to exist. 6. Under given conditions of species, sex, climate and use, a definite amount of digested organic matter is necessary to maintain a particular animal without gain or loss of body substance. This means simply that tissue wastes must be replaced, and the fuel sup- ply must be kept up. If the animal receives no food, or less than the amount needed for maintenance purposes, tissue waste and the production of energy do not cease, but go on wholly or in part at the expense of the body sub- stance, and, as it is commonly expressed, the animal "grows thin." 7. Food supplied above a needed maintenance quan- tity may be utilized for the production of new sub- stances or work or may be eliminated in part and increase the waste. Within limits, both things generally occur. In the proper sense of the term, no production ever occurs without an excess of food above the mainte- Laws of Nutrition 185 nance requirement. Milk formation may sometimes go on at the expense of the body substance, but with proper feeding, milk, flesh or muscular work are pro- duced at the expense of food supplied in excess of that needed for maintenance. 8. Regard must be had to the supply of particular nutrients as well as of total food. Even with an ani- mal doing no work and giving no milk a certain amount of protein will be broken up constantly into urea and similar compounds, an amount which will be withdrawn from the body tissues to the extent that it is not supplied by the food. In addition to this, a milch cow, for instance, must have protein for the formation of the nitrogen compounds of the milk, or a steer for the growth of flesh in a quantity proportional to the production, and food must supply it. There is, there- fore, a minimum supply of protein, which, in a par- ticular case, is necessary for maintenance and for constructive purposes, less than which ultimately dimin- ishes production to the extent of the deficiency, or else requires the use of body tissue. . 9. The different classes of nutrients are to some extent interchangeable in their functions. That is to say, all the organic nutrients may be burned to supply energy. Protein may be so used even to withdrawing it from the purposes to which it is necessary unless the carbohydrates or fats are sufficient to protect it from being consumed as fuel. A proper supply of the non- nitrogenous nutrients is required, therefore, to insure the application of the necessary minimum of food pro- tein to its peculiar uses. CHAPTER XIV SOURCES OF KNOWLEDGE The foregoing chapters embody many statements of principles and facts which have been made positively and without modification. To quite an extent these are based upon the conclusions of scientific men, that is, conclusions which have been reached after such study of the problems involved as is competent to secure ac- curate information. In some cases this study has been severe and long continued, having been carried on by the use of methods and apparatus capable of the most precise measurements. Moreover, in the investi- gations of science an effort has been made to pro- ceed logically, so that the results attained shall not be fallacious. Notwithstanding the fact that a great deal of our knowledge is the result of an earnest arid impartial search after truth, under conditions espe- cially favorable to its discovery, many persons are disposed to give more credit to the traditions and conclusions of practice than to the carefully prepared verdicts of science. It may not be out of place, therefore, to present in this connection some of the considerations and methods which have to do with the acquisition of knowledge concerning animal nutri- tion, for this may aid us to appreciate the value of (186) Real Value of Practical Observations 187 "well - established facts and to exercise caution in ac- cepting the verdicts either of science or of practice before they are thoroughly justified. There are three general ways in which we may be said to have acquired knowledge in regard to feed- ing animals: 1. The observation of ordinary practice. 2. Practical experiments, so called. 3. Scientific investigation. CONCLUSIONS OF PRACTICE Until within recent years, the practice of cattle- feeding has been entirely governed by the conclu- sions drawn from ordinary practice. Among the many men engaged in animal husbandry, certain ones pos- sessed of more than average powers of observation and business ability have secured good results with certain feeding stuffs and methods of feeding, and their practice has been accepted by their neighbors with no further demonstration than that these success- ful farmers sold fat cattle and obtained large returns from the dairy. During the centuries that man has had domestic animals under his care, certain results have appeared to follow from certain systems of feed- ing or the use of certain foods, and upon these so- called practical observations the feeder has built his creed. In these ways there have come to be accepted, sometimes locally and sometimes generally, standards of feeding as to quantity, kind of ration, and times 188 The Feeding of Animals of feeding. At the same time, it was necessary only to attend a farmers' convention fifty years ago to become convinced of a great variety of opinions as to the best methods of practice. In fact, opinion was the court of last resort. There were then no known, well-estab- lished fundamentals to which appeal could be made as a basis for discussion. While many false notions were entertained, many of the beliefs then prevailing were undoubtedly correct or contained a germ of truth. It is generally safe to assume that when an opinion is widely and persistently held it is not altogether with- out reason or foundation. It is often the expression, in more or less correct terms, of some important prin- ciple. No one should lightly turn aside from the traditions and convictions of a community in regard to any line of practice. A knowledge of the precepts governing the feeder's art that are the accumulation of experience in the care of animals is to be respected and is, to a great extent, essential to successful prac- tice. It is also true that little substantial progress can be realized in any art if its underlying truths are not understood, for when this is the case the results of experience under one set of conditions do not serve as a guide under circumstances entirely different. PRACTICAL FEEDING EXPERIMENTS With the advent of modern science and of the efforts to utilize it in agriculture, an attempt has been made to search for important truths more systematically, an effort undertaken chiefly by experiment stations. As Insufficiency of Some Experiments 189 one means of gaining knowledge, these institutions, and to some extent private farmers, have conducted many so-called practical feeding experiments in order to verify present beliefs, test theories and solve exist- ing problems. The relative value of various feeding stuffs and rations for producing growth and milk and the influence of different fodders and grain foods upon the quality of the product have been the subjects of numerous feeding tests. Much valuable information has been secured in this way, but there has not always been a full recognition, even by experiment stations, of the limitations which should be observed in drawing conclusions from this manner of experi- mentation. In order to view this matter more in detail, let us consider experiments in testing rations for growth and milk production. The usual method of procedure with such feeding trials is either to feed two lots of animals on the rations to be compared and note the comparative growth or milk yield, or to feed the same lot on one ration for a time and then change to another ration. If these tests are made with growing or fattening animals, the increase in live weight is taken as the measure of the relative efficiency of the rations com- pared. It should be said of these experiments that their apparent verdict is to be accepted with great caution, and definite conclusions are not justified until repeated trials of two rations or of two systems of feeding, made with the use of all possible precautions against error, and under a variety of conditions, give uniform and consistent results in the same direction. 190 The Feeding of Animals There are several reasons why this is so, the main one being that the increase in the weight of an animal is an uncertain measure of actual growth. Variations in the contents of the alimentary canal due to the irregular- ity of fecal discharge and to a lack of uniformity in the water drank may cause temporary variations in the live weight of considerable magnitude. Moreover, the nature of the growth of body substance is revealed by neither the mere weighing of an animal nor by his general appearance. Even if the changes in weight are due to an increase of body tissue, this may be more largely water in one case than in another,, so that the real contribution of the food to the dry substance of the body may not be shown. Nor is the character of the solids deposited in the animal discovered by merely weighing him. In fact, by such practical experiments we simply learn that one set of animals has gained more or less pounds of weight than another set, but the why and the how are not explained. Practically the same considerations pertain to feed- ing tests for milk production. When the milk flow from one ration is larger than from another, we can easily satisfy ourselves as to the comparative yield of milk solids, which is the real test of such production; but we are not able to decide whether the cow either may not have contributed to the milk secretion from the substance of her own body, or may not have gained in body substance, the extent of such loss or gain being greater, perhaps, with one ration than with another. Even if these uncertainties did not exist, we have Development of Necessary Knowledge 191 the still greater disadvantage of not learning by this means why a particular combination of feeds has superior qualities for causing growth or sustaining milk secretion. The mere data showing that an ani- mal ate so many pounds of food and produced so ruany pounds of beef or milk are important business facts, but they reveal nothing concerning the uses of the several classes of nutrients and of themselves fur- nish slight basis for developing a rational system of feeding. We must somehow learn the function of pro- tein, carbohydrates aud fats in maintaining the various classes of animals and the real effect of varying the source, quantity and relative proportions of these nutri- ents before we can draw safe general conclusions. CHEMICAL AND PHYSIOLOGICAL STUDIES As preliminary to more comprehensive and convinc- ing methods of investigating feeding problems, there has been going on during many years a necessary study of the compounds which are found in plants and ani- mals. Much has been learned about the ultimate com- position aud the constitution of the albuminoids, carbo- hydrates and fats, their physical and chemical proper- ties, the compounds into which these bodies break under certain conditions, the chemical changes to which they are subject through certain agencies, and their relation to one another. Investigations along these lines have for years occupied the time of some of our ablest scientists, and, while such researches when they were conducted may have seemed to the extreme 192 The Feeding of Animals utilitarian to be of little value, we now see how di- rectly they are contributing to human progress and welfare. To the above information has been added through physiological investigations a knowledge of the ways in which the several food compounds are transformed in digestion and in other metabolic changes, the avenues along which these compounds travel, and the ways in which their products of decomposition are dis- charged from the animal organism. We have learned how to distinguish between the digested and undi- gested food, have demonstrated that all the nitrogen of the decomposed proteids passes off in the urine, have measured the combustion of the nutrients and have learned how to strike a balance between the in- come and outgo of the animal body. It is now possi- ble to determine with reasonable accuracy just how much substance is retained or lost from the body of the experimental animal while eating a given ration, and what is the nature of the gain or loss. Very recently means have also been devised for measuring the heat given off by a man or an animal in order to ascertain the actual physiological values of different feeding stuffs. MORE ACCURATE METHODS OF INVESTIGATION In applying the principles and facts of chemistry and physiology, the first advance from the ultra -prac- tical feeding experiment in the direction of an accurate history of what occurs when the animal is eating a Progress in Experimental Methods 193 particular ration is the measurement of the digested nutrients and the determination of the gain or loss of nitrogen. This is accomplished, as heretofore stated, by ascertaining the quantity of various compounds eaten and the amount of the same in the feces, the differ- ence being the digested portion. The urine is also collected, and if the nitrogen in it is less or more than that in the digested protein, then the animal is either gaining or losing nitrogenous body substance, unless the measurement is with a milch cow, when the nitrogen in the milk must be taken into account. By an experiment conducted in this way, with careful and continued weighings of the experimental animal, it is possible to secure a probable relation between a unit of digested dry matter and a unit of production. Such a method has been used to determine what is a main- tenance ration for animals of several classes, and in those cases where the experiments have been continued for a sufficient length of time and have shown on repetition a reasonable agreement, we are justified in accepting the results as a close approximation to fact. When a ration keeps an animal in nitrogen equilibrium for one or more months and no material gain or loss of weight occurs, we may safely regard it as approxi- mately a maintenance ration under the conditions in- volved. Experiments of the same kind are equally useful in testing the productive power of various food combinations, and whenever by such continued tests one ration shows no superiority over another, it is safe to assume that no differences exist which would be especially important to the farmer's pocketbook. M 194 The Feeding of Animals RELATION OF FOOD TO PRODUCTION Another class of experiments somewhat more severe in their requirements are those designed to give infor- mation as to the relation between the constituents of the food and the growth of the various tissues in the animal body or the formation of milk solids. The ex- periments conducted by Lawes and Gilbert on the for- mation of fat with swine may be cited in illustration of the methods used. These were planned so as to learn the amounts of digested protein, carbohydrates and fat consumed by the animal and also the quantities of protein and fat stored in the body during a given period. "In experiment No. 1, two pigs of the same litter, of almost exactly equal weight, and, so far as could be judged of similar character, were selected." One was killed at once and its composition determined, and the other was fed for ten weeks on a fattening ration of known composition and then slaughtered and analyzed. The quantity of protein and fat which the pig's body had gained during the ten weeks as ascer- tained from the composition and weight of the two pigs was then compared with the food supply of simi- lar compounds. It was assumed that a pound of food fat could produce a pound of body fat and that 51.4 per cent of all the protein not stored in the body as such could be used for fat formation. Even with the most liberal allowances it was found that the pro- tein and fat of the food could not possibly have been the sole source of the new body fat, thus forcing the conclusion that the carbohydrates are fat -formers. Experiments on Use of Nutrients 195 Practically the same plan has been followed in study- ing the source of milk fat. Several cows were fed on carefully weighed and analyzed rations extremely poor in fat, and the amount and composition of the feces, urine and milk were ascertained during sixty to ninety days. The fat digested from the food and the theo- retical fat equivalent of the decomposed protein as measured by the urine nitrogen were charged up against the milk fat, and a large quantity of the lat- ter could be accounted for only as having had its source in carbohydrates. Another method of investigating fat formation has been used with dogs. It is well known that when an animal is deprived of food the expenditure of energy by the body is maintained at the expense of body sub- stance. Both muscular tissues and fatty substance are broken down and used in this way, the latter beiug regarded as furnishing the most natural and available supply of fuel. It was found in the case of dogs that after a certain number of days of starvation there oc- curred a sudden and large increase in the waste of nitrogen compounds as shown by the urine excretion, the explanation for this being that the body fat had become exhausted and a demand was at once made upon the proteid tissues for the necessary supply of energy. As soon as this rise of nitrogen waste appeared, then the dog was allowed to eat, and whatever fat was found in the body at the end of the feeding period was regarded as having been formed from the food taken after the starvation period. If, for instance, the ration was wholly protein and fat was found to have become de- 196 The Feeding of Animals posited in the body, this was regarded as proof of the formation of fat from protein. Such experiments as these have not always been conclusive, although they are regarded by some scientists as haviug furnished proof that protein may be a source of fat. THE RESPIRATION APPARATUS After all, the investigations of the kinds described fail to furnish data so accurate and so complete as are necessary for entirely safe conclusions. In every in- stance, one or more assumptions are involved where definite proof is not furnished. Nothing short of a complete record of the income and outgo of the ani- mal organism during the experimental period is con- clusive evidence as to whether there has been a gain or loss of body substance and what is the kind and extent of the growth or waste. The securing of such a record is an expensive and laborious task. It re- quires not only complete information in regard to the quantity and composition of the food, but also an ac- curate measurement of the excreta, including the feces, the urine, the respiratory products and the matter given off through the skin. Such measurements are taken by means of a respiration apparatus, a costly and complicated mechanism, a detailed description, of which would be of little use to most readers. It is sufficient to state that this apparatus makes possible the collection and analysis of all the excretory products,, whether solid or gaseous. The experimental man or animal lives in a closed chamber into which is intro- Investigation with Respiration Apparatus 197 duced food and fresh air and from which is pumped the vitiated air, the water and carbon dioxid of which are absorbed and weighed. All conclusions drawn from experiments with the respiration apparatus are based largely upon the in- come and outgo of nitrogen and carbon. As carbon is a constituent of all possible compounds of the ani- mal body except the mineral, it is certain that when the body gains in carbon it gains in organic sub- stance of some kind, and if it loses in carbon there is a waste of organic body substance. The general character of the gain or loss can be determined by the nitrogen balance. If more nitrogen is taken in by the experimental animal than is given off, it is clear that the nitrogen compounds of the body have received an accession. Knowing as we do the proportions of nitro- gen and carbon in the various tissues of the animal, we can calculate how much of the gain or loss of carbon belongs in the nitrogenous substance deposited or wasted. If more carbon is gained or lost than can possibly be associated with the nitrogen gained or lost, then there has been a gain or loss of fat, because protein and fat being the main constituents of the animal car- cass, any considerable retention of carbon must be in one of these forms. If there has been nitrogen equilibrium, all excess or deficit of carbon belongs to a deposit or waste of fat. By such searching methods as these, it is possible to ascertain with a good degree of accuracy how food is used and what quantity and kind of nu- trients are needed in maintaining an animal under given conditions. 198 The Feeding of Animals DETERMINATION OF ENERGY VALUES We have reached a point in our study of animal nutrition where we realize that food values are to some extent commensurable with energy values and that it is desirable to know the energy product of different compounds and feeding stuffs. Moreover, we cannot possess sufficiently full knowledge concerning the energy needs of the several classes of animals until we have measured energy consumption under the various conditions of work and of production. The mere determination of the income and outgo of the animal body does not necessarily measure energy needs or use. We may go so far as to ascertain that a certain amount of carbon from a certain source was consumed in a given time, but from this alone we do not learn the extent to which this combustion has supported the internal and external work of the body. Calculation of the energy value of a ration. — Three methods may be adopted for determining the energy expenditure by an animal eating a given ration. The one of these most easily carried out is largely a matter of mathematical calculation. By the use of average digestion coefficients it is possible to ascer- tain approximately the amounts of digestible protein, carbohydrates and fats contained in any ration which is apparently accomplishing a desired result. We know from previous determinations what are the calorific values of individual compounds such as albumin, starch, sugar, stearin and olein, and these compounds are assumed to represent the energy value of the Establishing Energy Values 199 classes of nutrients to which they belong. If, then, we multiply the calculated quantities of digestible pro- tein, carbohydrates and fats by their respective as- sumed energy factors, we get a number which may be taken as an expression of the available energy of the ration under consideration. This method cannot be regarded as entirely accurate, because the calorific value for protein may not be the same as that for any single albuminoid, and the heat units of the nitrogen-free extract are likely to vary materially from those found for the starches and sugars, while the ether extract is very far from representing the pure fats. At the same ,time, it is possible in this way to learn the energy value of a ration closely enough, perhaps, for all prac- tical purposes. Energy value of digested nutrients. — A second method, which is probably a step in the direction of greater accuracy, is to determine by the use of a calorimeter the heat units of the ration and also of the urine and feces. The differences between the food heat units and those found for the excreta are assumed to represent the energy value of that por- tion of the ration appropriated by the animal. Pro- vided the heat units obtained in calorimeter combus- tion and physiological combustion are equivalent, this method must be considered as furnishing a reliable energy measurement. However probable this equivalence may seem, it has not been fully demonstrated. We still need more complete experimental proof that the oxidation of the several food compounds in ordinary combustion and in the animal produces identical re- 200 The Feeding of Animals suits in the two cases. Even if this method gives us a correct estimation of the energy equivalent of the food used, it furnishes no definite information as to the manner of use. It does not appear to what ex- tent the digested nutrients have been oxidized with a corresponding radiation of heat or whether there has been a gain or loss of body substance. If there has been a gain of body substance, then the needs of the work horse or milch cow, if these are under considera- tion, are less than the heat units of the ration, but if there has been a loss of body substance, then the ration is below the required standard for the par- ticular animalr under investigation. In a study of energy relations, it is therefore even more necessary to resort to a respiration apparatus of some sort than in determining food balances. We must learn the actual extent of the food combustion which occurs if we would have all the data necessary for measuring energy used, and here we come to the third and most accu- rate method of determining energy expenditure; viz., experiments with a respiration apparatus. Measurement of food combustion. — There are two general ways of ascertaining the extent to which food is burned by any living organism. One is to measure the products of combustion and the other is to measure the amount of oxygen used. It is self- evident that no combustion can occur without the use of oxygen, and so if the experimenter is able to learn just how much of this element is taken up in uniting with the carbon and hydrogen of the food, he has a direct and accurate means of measuring actual Respiration Calorimeter 201 energy production. The older forms of respiration ap- paratuses simpty allowed an estimation of the carbon dioxid and water given off by the animal. How much of the water was formed by the oxidation of the hydrogen of the food and how much was simply evapo- rated from the store taken in as water, it was impos- sible to know by direct determination. This could only be calculated. The carbon dioxid was, on the other hand, a direct and accurate measure of the com- bustion of carbon. Later devices, as, for instance, the one used by Zuntz, allow a direct determination, not only of the products of combustion, but of the oxygen absorbed by breathing. This method of work has great advantages, as one measurement not only checks the other, but makes it possible to ascertain the actual oxygen consumption during any given period of the experiment, as, for instance, when the animal is at rest, when masticating food, or when performing a given amount of external work. In this way, Zuntz made his masterly demonstrations of the differences in the net values of different foods due to the greater energy cost of masticating and digesting certain ones. Respiration calorimeter . — None of the older appara- tuses, whether allowing the determination of oxjgen consumption or not, measured the heat radiation from the animal body, or, in other words, the amount of energy actually evolved from internal combustion. Recently Professors Atwater and Rosa have devised a respiration apparatus which is at the same time a cal- orimeter. The quantity of heat radiated from a man or other animal confined in this calorimeter is absorbed 202 The Feeding of Animals by a known volume of water and is thus determined. This is a great advance towards certainty, because direct measurements of the energy of a ration in use are thus made possible and the necessity for theoreti- cal assumptions is largely removed. It is already made clear to the reader, doubtless, that the demonstration of facts and principles in the domain of animal nutrition is exceedingly difficult. It should be equally clear that when conclusions are reached in ways which have been briefly described, they are worthy of respect and should have greater weight than the necessarily imperfect observations of common practice. Science often errs in her deduc- tions, but the efforts of her workers are constantly directed towards the elimination of false conclusions, so that unsound theories are not likely to be accepted for a great length of time. PART II— THE PRACTICE OF FEEDING CHAPTER XV CATTLE FOODS — NATURAL PRODUCTS The number of cattle foods now available for use is very large, and the list appears to be constantly increasing. Not only have several fodder plants been added to those formerly grown, but we have now a great variety of waste products from the manufacture of oils, starch, and human foods that are being placed upon the market as feeding stuffs. At one time farmers produced all their cattle ate, and this was done without going outside a very limited list of forage plants and grains. All this is changed, especially in the older, more thickly -settled portions of the United States, so that considerable knowledge is now needed regarding the composition and specific characters of the numerous kinds of feeding stuffs if they are to be used intel- ligently. It will aid in discussing this branch of our subject if we first note the divisions into which the materials used for feeding farm animals are grouped. There is more than one basis upon which it is possible to make these divisions, — botanical relations, the portion of the plant used, whether stem or fruit, and chemical com- position. As a matter of fact, all these and other (203) 204 • The Feeding of Animals distinctions are involved in the classification of the cattle foods in common use at the present time. The feeding stuffs of vegetable origin are generally divided into four classes: (1) forage crops, consisting of the stem and leaves of herbaceous plants, either in green or air -dry condition, to which is attached in some cases the partially formed or wholly mature seed or grain; (2) roots and tubers, or the thickened under- ground portions of certain plants; (3) seeds or grains; (4) parts of seeds or grains which are the by- products from the removal of other parts by some manufacturing process. These are the commercial by-product feeding stuffs. FORAGE CROPS The valuable forage plants of the United States belong mostly to two families, the grasses (graminese) and the legumes (leguminosae) . June grass, red top, timothy and the cereal grain plants are types of the former; and the clovers, alfalfa (Fig. 3), the vetches, and peas, of the latter. Whether in the pasture or in tilled fields, few plants outside of these divisions con- tribute materially to the supply of high -class fodders. The most essential difference between the members of these two families of plants when considered as feeding stuffs is the larger proportion of nitrogen compounds in the legumes. It is characteristic of all legumes that their proportion of protein is high as compared with any other forage crops, and for this reason they are greatly prized on dairy farms. The fact that they are regarded as increasing materially the nitrogen supply Influence of Drying Fodders 205 of the farm from sources outside the soil also adds to their value. Green vs. dried fodders. — Conditions of drying. — Nearly all of the herbaceous plants that are grown for consumption by farm animals may be fed either in a green or dry state. Oats, maize, clover, alfalfa, and other species which serve so useful a purpose as soil- ing crops for summer feeding are also dried that they may be successfully stored for winter feeding, though Fig. 3. Crop of alfalfa, New York State Experiment Station. maize, and, to some extent, other crops, are now pre- served in a green condition through the process of ensilage. The advantages and disadvantages of green as com- pared with dry fodders have been much discussed, and some of the facts, chemical and otherwise, bearing upon the question are presented in this connection. It is safe to assert that the compounds of a dried fodder which has suffered no fermentation are practically what they were in the green, freshly-cut material, excepting that nearly all of the water contained in the green 206 The Feeding of Animals tissues has evaporated and that in drying there is a possible loss of an imperceptible amount of volatile compounds, whose presence in the plant affects its flavor more or less. It is certain that curing a plant generally diminishes its palatableness and increases its toughness, or its resistance to mastication, although with many crops, as for instance the early -cut native grasses, these changes do not affect nutritive value to a material extent. There is no question but that the mere matter of being green or being dry has very little influence upon the heat which a fodder will develop when burned or upon the extent to which it will sustain growth or milk formation. We must, how- ever, take into account the desirability of the highest state of palatableness. It is a fact that drying fodders under perfect con- ditions is often not possible. The long -continued and slow curing of grass in cloudy weather, especially when there is more or less rainfall, is accompanied by fer- mentations that result in a loss of diy substance more or less extensive, and which involve some of the most valuable compounds, principally the sugars. The tissues of certain plants, maize for instance, are so thick that rapid curing in the field is never pos- sible, and fermentative changes are unavoidable. It is probable that maize fodder and stover are never field- dried without a material loss in food value, for the chemist finds that even when the stalks are finely chopped, drying by artificial heat is necessary to a complete retention of the dry matter. The extent of the loss from curing fodders must be very variable. Conditions of Curing Fodder 207 So far as we know, grass, which in "good haying weather" is well stirred during the day and packed into cocks over night so as to avoid the action of heavy dew, suffers practically no deterioration, while dull weather or rain may cause a serious loss. It is doubtful, however, whether night exposure during good weather is sufficiently injurious to justify the expense of cocking partially cured hay. On the other hand, the economy of using hay caps during unfavorable weather is without question. The over -drying of hay before raking into winrows and "bunching" so as to cause a loss of the leaves and the finer parts through brittleness may be as wasteful as under -drying and the consequent fermentation. Over -dried hay does not pack well in the mow and is less palatable. The leguminous hays, such as clover and alfalfa, are es- pecially subject to loss from over -drying before han- dling. Fodder crops, if dried at all, should be dried to such a per cent of moisture that they will not "heat" to discoloration after being packed in large masses and lose dry matter from the same general causes that operate in field - curing under bad con- ditions. The harvesting of forage crops. — The result to be achieved in the growing of forage crops is the produc- tion on a given area of the maximum quantity of di- gestible food materials in a palatable form. The age or period of growth at which a forage crop is harvested is an important factor in this relation and may affect the product in three ways: (1) in the quantity of ma- terial harvested, (2) in the composition of the crop, 208 The Feeding of Animals and (3) in the palatableness of the resulting fodder. In discussing this question we must recognize the fact, first of all, that in these respects no general conclusion is applicable to all crops. What would be wisest in the management of the meadow grasses might be wasteful in handling the legumes, and especially so in harvesting maize. The truth of this statement will appear as the facts are displayed. It is safe to assert that in general the maximum quantity of dry matter is secured when forage crops are allowed to fully mature and ripen. The only exception to ihe rule is found in the legumes such as the clovers and alfalfa, where at maturity the leaves unavoidably rattle off and are lost, either before or during the process of curing. The fact that growth of dry matter takes place up to the time of full maturity is well illustrated by the results of experiments conducted on the farms of the Pennsylvania State College, the New York Experiment Station, and the University of Maine, in cutting timothy grass, clover, and maize at different stages of growth. These results are sum- marized in the accompanying tables: Timothy grass (yield of dry hay per acre) Results in Pennsyl- ^-Results in Maine—- vania— two farms av. 3 years 1 year av. 2 years 1878-1880 1889 1881-1882 Stage of growth lbs. lbs. lbs. Nearly in head 3,720 Full bloom 4,072 4,225 2,955 Out of bloom or nearly ripe . 4,136 5.086 3,501 Ripe 3,832 Influence of the Stage of Growth 209 Maize for silage {yield of dry matter per acre) New York Maine 1889 180d Stage of growth lbs. lbs. Tasseled to beginning of ear 1,620 3,064 Silked to some roasting ears' 3,080 5,211 Watery kernels to full roasting period . 4,640 6,060 Ears glazing 7,200 6,681 Glazed to ripe 7,920 7,040 Bed clover (yield of dry matter per acre) Pennsylvania 1882 Stage of growth lbs. In full bloom 3,680 Some heads dead 3,428 Heads all dead 3,361 These data are convincing testimony as to the growth of dry substance in certain forage crops up to and including the period of ripening. Clover is an apparent exception, but is probably not really so be- cause after the heads begin to die there is an actual loss of dry matter from the shedding of the leaves. It does not follow when a plant increases in its yield of dry matter that its nutritive value has pro- portionately increased. The end to be sought is the largest possible quantity of available food compounds, and it is entirely possible that changes in texture and in the composition of the dry substance may partially or fully offset the greater yield. With the meadow grasses this undoubtedly happens. The dry matter of mature grass contains a larger proportion of fiber than the immature. • The progressive increase of fiber as the plant approaches ripeness is well illustrated by- analyses made at the Connecticut Experiment Sta- N Ash Protein Crude fiber Nitrogen- free extract Fats 4.7 9.6 33. 50.8 1.9 4.3 7.1 33.3 53.3 2. 4.1 7.1 33.8 53.3 1.7 3.6 6.8 35.4 52.2 2. 210 The Feeding of Animals tion of a sample of timothy grass cut at different periods of growth: Composition of dry substance {per cent) Stage of growth of timothy Well headed out .... In full blossom When out of blossom . Nearly ripe 3.6 These analyses show that the changes are not con- fined to an increase of fiber. The relative proportions of ash and protein grow less as the plant matures. An examination of the nitrogen -free extract would prob- ably show an accompanying decrease of the soluble carbohydrates. The combined effect of these changes is to cause the plant to harden in texture and become less pala- table. The digestibility is naturally affected. Three American digestion experiments with timothy hay cut in bloom or before show an average digestibility of the organic matter of 61.5 per cent, the average from four experiments with timothy cut when past bloom being 55.4 per cent. Doubtless the increase in dry matter when timothy stands beyond the period of full bloom no more than compensates for the decrease in digesti- bility. Using the average coefficients of digestibility and the average yields, as given in this connection, the yield of digestible organic matter would be in full bloom, 2,306 pounds, and when out of bloom or nearly ripe, 2,350 pounds. If one considers the decrease in pala- tableness the advantage is with the earlier cut hay. Influence of the Stage of Growth 211 These facts do not pertain to timothy alone. Other meadow grasses are similar in their characteristics of growth. The clovers, and especially alfalfa, deteriorate to a marked degree from the same cause when allowed to ripen too fully before cutting. It is probable, all factors considered, that if the grasses and clovers which are cut for hay could be harvested when in full bloom a desirable compromise would be effected between quantity and quality. Al- falfa should be cut no later than when the first bloom makes its appearance. Conditions are quite different with maize. This plant in maturing gains not only in quantity but in quality. In support of this statement data are cited from an experiment conducted at the Maine Experi- ment Station. The following is the composition of the dry matter of the corn when cut at several periods of growth : In 100 parts water- free substance of maize Stage of growth Ash Very immature, Aug. 15 9.3 A few roasting ears, Aug. 28 . . 6.5 All roasting stage, Sept. 4 6.2 Some ears glazing, Sept. 12. . . . 5.6 All ears glazed, Sept. 21 5.9 Here we see the same decrease in the proportions of ash and protein as occurs with timothy, but, unlike timothy, the maturing of the maize causes a decrease in the percentage of fiber and a material increase in the relative amount of the soluble carbohydrates, sugar and starch. Protein Crude fiber Sugar Starch Total nitrogen free extract Fat 15. 26.5 11.7 46.6 2.6 11.7 23.3 20.4 2.1 55.6 2.9 11.4 19.7 20.6 4.9 59.7 3. 9.6 19.3 21.1 5.3 62.5 3. 9.2 18.6 16.5 15.4 63.3 3. 212 The Feeding of Animals These data give us every right to expect that the dry matter of the mature corn plant is more digestible than that of the immature plant, and experimental tests show this to be the case. There follows a sum- mary of American digestive experiments bearing on this point: Digested from 100 parts organic matter i — Corn fodder — - < Corn silage « Max. Min. Av. Max. Min. Av. Cut before glazing, 13 experiments . . 71.4 53.6 65.7 77.8 56.6 67.4 Cut after glazing, 10 experiments.... 74.2 61.2 70.7 80.2 65.2 73.6 The advantage is seen to be with the mature corn. It is fair to conclude from all these observations that harvesting the corn plant when immature is injudicious from every point of view. SILAGE About twenty -five years ago a new process for pre- serving crops in a green condition was introduced into the United States; viz., ensilage. This consists in storing green material in receptacles called silos, in masses sufficiently large to insure certain essential con- ditions. Within a brief period after maize or other green material is packed in a silo, the mass becomes perceptibly warm and in the course of two or three days it reaches its maximum temperature, which is much above the average heat outside. This rise in temper- ature is due to chemical changes which involve the consumption of more or less oxygen and the produc- tion of compounds not previously existing in the fresh material. Silage Formation 213 Nature of the changes in the silo. — These changes are very complex. They have been regarded as due to the activity of a variety of ferments, principally those which are believed to cause the formation of alcohol and acetic, lactic and other acids. Whether the oxi- dations occurring in the silo are wholly induced by ferment action or in part at least are the result of oxidations brought about in other ways is a point over which there has been some recent interesting discussion. Babcock and Russell have carried on at the Univer- sity of Wisconsin, able and very suggestive inves- tigations concerning the causes of silage formation. They conclude that the theory that silo changes under normal conditions are due wholly to bacteria "does not rest on a sound experimental basis.' 7 Their data lead them to regard respiratory processes, both direct by the plant cells and intramolecular, as the main causes of the chemical transformations which produce carbon dioxid and the evolution of heat within the ensiled mass. The direct respiration appropriates the oxygen confined in the air spaces of the silo, and the intramolecular respiration uses oxygen combined in the tissues. Both forms of respiration go on only so long as the plant cells remain alive. Concerning bacteria the authors say: "The bacteria, instead of function- ing as the essential cause of the changes produced in good silage, are on the contrary only deleterious. It is only where putrefactive changes occur that their influence becomes marked." Whatever are the inducing causes, the chemist finds, when he keeps a careful record of what takes place in 214 The Feeding of Animals the silo, that the silage contains considerably less dry substance than the original fresh material. In some way loss has occurred through the formation of volatile products. An examination of the fresh corn and of the silage shows, moreover, that the latter contains much less sugar than the former, sometimes none at all. In the place of the sugar we find a variety of acids, chiefly acetic and lactic. This is a change similar to the for- mation of acetic acid in cider and lactic acid in milk, in all cases sugars being the basal compounds. Along with the development of these acids, carbon dioxid and water are formed from the carbon compounds of the ensiled material. In other words, combustion takes place and more or less of dry matter is actually burned up, thus generating heat and causing rise of temperature of the fermenting mass. The amount of dry matter thus lost is determined partly by the kind of crops and the care with which the silo is built and filled. Another important chemical change induced by fer- mentation is a splitting up of a certain portion of the proteids of the fermenting material into amides, com- pounds which, as we have learned, have a more limited nutritive function than the proteids. Investigation conducted at the Pennsylvania State College showed that in some cases over half the nitrogen of silage existed in the amide form, this being between two and three times as much as was found in the original fodder. Probably the same change takes place in the field- curing of fodder, but no data are available on this point. All observers agree so far that with normal silage much the larger part of the material lost is sugar. Changes and Losses in the Silo 215 Starch seems to resist the usual silo oxidations. In certain experiments a considerable loss of nitrogen is reported. It is hard to understand, though, how this can occur to any large extent unless the conditions in the silo are very bad, so that putrefactive fermentations set in. An extensive loss of nitrogen compounds cer- tainly would indicate very serious and long -continued destructive changes. The nature of the changes and losses in producing silage have been dwelt upon partly because corn, the principal silo crop, is one of our most important forage crops, perhaps the most so on a dairy farm, and partly in order to illustrate the necessity and value of good management in preserving this crop by the silo method. Moreover, the loss that is incident to the field -curing of maize is practically the same in kind and is fully as large as that pertaining to silage, so that the facts pre- sented are pertinent to both methods as well as to all circumstances where similar oxidations and fermenta- tions are likely to ensue. Extent of loss in the silo. — The extent of the loss of dry substance is important. It measures in a general way the difference between the food value of the silage and of the fresh material. The silo combustion reduces the energy or heat value which the fermented fodder will have whenever it is eaten by the animal. The heat lost would warm an animal during a cold day were the combustion to occur within the animal instead of in the silo. It is desirable, therefore, to know the extent to which dry substance is actually broken up in the preparation of silage. This loss has been measured 216 The Feeding of Animals by several investigators, and, as was to be expected, it has been found to depend greatly upon the condi- tions involved, the figures reached varying from about 2 per cent to nearly 40 per cent of the dry matter of the fresh crop. In a majority of cases the loss has been over 15 per cent and less than 20 per cent. Professor King, of the Wisconsin Experiment Station, who has given the production of silage much study, concludes upon the basis of his observations that in good prac- tice the necessary reduction of dry matter in making corn silage need not exceed 4 to 8 per cent, and with clover silage from 10 to 18 per cent. The necessary loss is explained as being that which occurs in the interior of the mass where all outside air is excluded and other favorable conditions prevail. Considering the contents of the silo as a whole, it will require care- ful attention to all details in order to reach Professor King's estimate with the best conditions attainable. This investigator found that 64.7 tons of silage packed in a silo lined with galvanized iron, thus secur- ing a perfect exclusion of air, lost an average of 6.38 per cent of dry matter. This silo was filled in eight detached layers, and the proportion of loss in these sev- eral divisions, as affected by location, is most suggestive: Surface layer. . . 8,934 lbs., lost 32.53 per cent dry matter Seventh layer . . 8,722 Sixth layer 14,661 Fifth layer 48,801 Fourth layer ...13,347 Third layer 7,723 Second layer . . .12,689 Bottom layer... 12, 619 23.38 10.25 2.10 7.01 2.75 3.53 9.47 Extent of ISilo Losses 217 The mean loss of dry matter in the lower six layers was only 3.66 per cent. These figures show that it is profitable to make the walls of the silo air-tight, even at large expense. The importance of reducing the loss in the silo to the lowest possible percentage is almost self-evident. As this point is capable of mathematical demonstration, it will be interesting and suggestive to calculate what might take place in a hundred -ton silo. In many of the trials which appear to have been conducted under not unusual conditions, a loss as high as 20 per cent of the dry matter put in the silo has been observed. In a hundred -ton silo filled with corn containing 25 per cent of dry matter, or 50,000 pounds, this would amount to the destruction of 10,000 pounds of dry food sub- stance. As the loss falls chiefly on the sugars or other soluble bodies which are wholly digestible, the available nutrients in the fresh material are diminished by an amount of digestible dry matter, equivalent to what would be required by ten milch cows during two months. If, therefore, < by good planning and extra care this waste could be reduced three -fourths or even one -half, the food resources for carrying a herd of cows through the winter would be materially increased, from five to seven and one -half tons of timothy hay being the measure of the saving in a hundred -ton silo. Ensiling vs. field-curing. — The question is often raised whether ensilage or field - curing is the more wasteful method of preserving a forage crop. Con- siderable study has been given this matter, and the results secured have been taken as a justification of the 218 The Feeding of Animals statement that one method is about as economical as the other, which is correct if we consider only the out- come of certain comparisons. A general survey of the data accumulated shows that on the whole the waste has been the larger in field - curing. Observations made in six states reveal a loss by the old method as low as 18 per cent in only one case, and from 21 per cent to 34 per cent in all others. Possibly under favorable conditions of weather, field -cured corn fodder may lose as little dry matter as silage, though this is doubtful, but in bad weather the waste from the ex- posed fodder is extensive. The greatest advantage in silo preservation is that conditions can usually be con- trolled with more satisfactory average results than are possible in field -curing. Other advantages pertain to the silo which are of a business nature and which need not be discussed here, further than to affirm- that the cost of a unit of food value is in general diminished by the use of the silo. Crops for ensilage. — The number of crops that may be successfully ensiled is not large. Maize is the most valuable one for this purpose, and clover is stored in this manner with a fair degree of success. So are peas, especially when mixed with corn. The true grasses and cereal grains outside of corn are not de- sirable silo crops, first because the silage from them is generally poor in quality, and second because usually they may be successfully and more cheaply stored in an air -dry condition. Any crop with a hollow stalk, giving an enclosed air space, — oats, for instance, — is not adapted to silo conditions, and there is no justification Construction of the Silo 219 for ensiling any fodder which is susceptible of prompt and thorough drying in the field, because in such cases there is an unnecessary waste of food substance by fer- mentation and an unnecessary handling of many tons of water contained in the green material, with no com- pensating advantages. But any crop used for the production of silage should be managed in the most efficient manner. A few general facts may be discussed in this connection. Construction of silos. — Silos that are of proper construction and shape have air-tight perpendicular walls and a height considerably in excess of either of the horizontal dimensions. These conditions are essen- tial to the completest possible exclusion of air and to the closest possible packing of the material, with a minimum of exposed upper surface. Silos may be either round, square or rectangular, provided that in the latter case one horizontal dimen- sion is not too greatly in excess of the other. The shape of a silo which is most economical and efficient is not the same for all conditions, although the round and square forms hold most in proportion to the wall area. Many farmers desire to have the silo in the barn, and generally there the square or rectangular form is more economical of space than a round one. When built outside the barn, the round form, according to the opinion of many, may be used to advantage both as to expense and results. If a square or rectangular silo is built the corners should be cut off inside in order to prevent an access of air and the decay which occurs at those points when this is not done. Several 220 The Feeding of Animals kinds of materials have been used in building silos, wood, brick, and stone, the former material proving to be the most satisfactory. If the walls are of masonry the inner surface must be cemented not only air-tight but so smoothly as to allow easy and uniform settling of the silage without leaving air spaces. If wood is used, which is certainly to be preferred, the inside con- struction must meet the same requirements. Lining a wooden silo with iron has been suggested as practical and economical. Economj- demands that as a pre- ventive against decay the inner woodwork should at least be treated with some preservative, which may also serve the purpose of obviating excessive swelling and shrinking of the lining boards. Filling the silo. — The condition of the crop and the manner of filling a silo determine to a great extent the character of the silage. Obviously it should be so done as to reduce the loss of food compounds to the lowest possible point. Three points are prominently discussed in this connection: (1) the condition of the crops; (2) the preparation of the material, and (3) the rate of filling. Experience has thoroughly demonstrated that the maturity of a crop influences its value for silage. This is known to be especially true of the corn crop. An immature corn fodder, which always carries a high percentage of water with less of the matured products, such as starch, is always certain to change to very acid silage. On the contrary, mature corn, when properly handled, is converted into a product with the minimum acidity and with an appearance and aroma much Filling the Silo 221 superior to that from the immature plant. Neither are satisfactory results secured from material that is over- dry. It may be stated in general terms that the best results are obtained when the proportion of dry matter falls between 25 per cent and 30 per cent. If corn is harvested for the silo after the kernels have begun to glaze, while the leaves are still green and before they show dryness, other conditions being favorable, it will meet every requirement for good silage. Whether the material with which a silo is filled shall be put in whole or after cutting or shredding depends to quite an extent upon its degree of coarseness. It is probable that clover, and even the smaller varieties of maize, are often successfully preserved without cutting, but no one professes that this can be done with the coarser varieties of maize. It is generally admitted that, with maize, cutting or shredding it increases the probability of satisfactory preservation, because the finer mechanical condition allows more uniform pack- ing and prompter and more uniform settling. The highest grade of silage with the minimum loss is undoubtedly more surely made from cut or shredded material. In the early days of silos it was taught that to insure the least possible waste by fermentation, the silo should be filled with the maximum rapidity and then promptly weighted. Following this view was the con- clusion on the part of some that very slow filling with no packing other than that given by the weight of the mass, was the proper way to make silage of the highest quality. This method was advocated for producing 222 The Feeding of Animals sweet (?) silage. It allowed violent fermentation at first with resulting high temperatures, by which means bacteria were supposed to be killed and subsequent fermentations prevented, a conclusion so far not sus- tained by scientific observations. At the present time moderately slow and continuous filling, rather than very rapid, is advocated by leading authorities. Two advantages are claimed for this method, one being that more material can be stored in the silo and the other is that silage of a higher quality is produced with a smaller loss of dry matter. The first point must be conceded and the second claim may be true, although in part it lacksiDroof. It is hard to understand why slow filling, especially if intermittent, should not increase rather than decrease the losses of food compounds. Certainly the less compact the mass the more intense the oxidation and the higher the temperature, the latter condition indicating with certainty the extent of the combustion. This point is illustrated by results reached at the Pennsylvania State College when the chemical changes in two large tubs of sorghum silage were studied, one of which was compactly filled and weighted at once and the other loosely filled and weighted after five days. The temperature rose seventeen degrees higher in the latter than in the former, with a loss of two and one -half times as much organic matter from the loosely filled tub. It follows from the theory of Babcock and Russell, previously noted, that the less the oxygen available in the air spaces and the quicker the plant tissue dies the less will be the combustion or loss of organic matter. These authors suggest as a The Straws 223 practical application of their theory that the air be excluded from the silo as rapidly as possible and only mature corn be ensiled, because such tissue will die sooner than immature, having less vitality. Their data seem to prove conclusively, also, that the evolution of much heat when a fodder is first ensiled is not essential to the formation of first-class silage. The repeated exposure of a loose upper stratum, which occurs with slow, intermittent filling, must cause extensive loss from portions of the silo. It must be held, in view of the experimental data now at hand, that the more promptly the air is excluded and expelled by the re- duction of the contents of the silo to a condition of maximum compactness, the less will be the fermenta- tion losses. The term "sweet silage" means but little as indicating completeness of preservation, for it may even be the result of extensive fermentations, a condi- tion expensively secured. Its significance is entirely different when the sweetness is due to proper maturity of the fodder plant. THE STRAWS When the grain plants which produce seeds val- uable for cattle and human foods are threshed, or in some way manipulated to remove the seeds, the other parts of the plant constitute what we call straw in the case of the cereal grains and le- gumes, and stover in the case of maize. These fod- ders differ from the same plants, when cut in a less mature condition for haj r or fodder, in being more tena- 224 The Feeding of Animals cious and less palatable, with a smaller proportion of the more soluble, and therefore more valuable, com- pounds. The most useful of these materials for feed- ing purposes are corn stover, oat straw, and the legume straws. These are better relished by farm animals than wheat and barley straws, which are utilized mostly for litter. ROOTS AND TUBERS Certain species of plants, more especially beets, mangel -wurzels, turnips, rutabagas, carrots and pota- toes, are agriculturally valuable because of the store of nutrients which they deposit in subterranean branches or in roots. The origiual purpose of this deposit is, in the case of potatoes and artichokes, to nourish the young plants of the next generation, or, in the case of biennials like beets, to supply the materials for the seed -stalk and seeds of the second year. Potatoes are not grown primarily as food for cattle, but roots have for many years been a standard crop for feeding pur- poses, especially in the production of mutton and beef. This class of crops has the advantage of furnishing very palatable, succulent food, which may be kept in perfect condition during the entire winter season, an advantage which is not wholly measured by the actual quantity of nutrients supplied by these materials. The disadvantages of these crops are that they are somewhat expensive to grow and necessitate the han- dling of large weights of water. A ton of turnips or mangels may furnish even less than 200 pounds of dry substance, to secure which 1,800 pounds of water must Boots, Grains and Seeds 225 be lifted several times. The percentage of dry matter in roots and tubers varies in American products, on the average, from 9.1 per cent in mangel -wurzels and turnips to 28.9 per cent in sweet potatoes. Potatoes are more nutritive pound for pound than roots. The dry matter of this class of cattle foods is principally carbohydrate in its character, though the proportion of protein is as large and in some cases larger than in certain grain foods. Two conditions are essential to the winter storage of roots without deterioration; viz., a low temperature, as near freezing as possible, and abundant ventilation. Large masses of roots unventilated are apt to "heat," and sometimes decay, with a resulting large loss in nutritive value. GRAINS AND SEEDS The conditions which provide for the maintenance of plant life also subserve the interests of the animal kingdom. We have seen that this is true of the store of starch and other compounds in tubers and roots, and it is a fact of much larger significance in the production of seeds, especially those of our cereal grains, including barley, maize, oats, rice, rye and wheat. Other seeds, such as buckwheat, cottonseed, flaxseed, beans and peas, also contribute an important addition to our animal feeding stuffs. In all these species there is deposited in the seed-coats and either around the chit or embryo or in the seed-leaves of the embryo, a store of protein, starch and oil, the purpose of which is to supply materials for growth during 226 The Feeding of Animals germination. This deposit of plant compounds repre- sents the highest type of vegetable food, whether we consider concentration, palatableness or nutritive effi- ciency. Besides, it is in such form that with ordinary precautions it is capable of indefinite preservation, without loss. It often occurs that when newly -harvested grain is stored in bulk it heats and grows "musty." This condition is due to fermentations that are made pos- sible by the high water content of the fresh grain and which involve a loss of dry substance. It is very de- sirable that grain shall be thoroughly dried before threshing, and it is generally necessary to secure additional drying after threshing before storing it in large bins. The agricultural value of the cereal grains is much enhanced by their adaptability to a great range of soil and climatic conditions. They are the American farmer's great reliance for the production of the high- est class of cattle foods. Maize, especially, is grown from Maine to Florida and from the Atlantic to the Pacific. These crops are useful, not only for their seeds but as fodder plants. For soiling purposes, as well as a source of dried forage, they are indispen- sable. CHAPTER XVI CATTLE FOODS— COMMERCIAL FEEDING STUFFS The cereal grams and other seeds are the source of a great variety of by-product feeding stuffs which have a large and widespread use, especially in the dairy sections of the United States. In the preparation of a great variety of human foods and of other materials important in industrial life, certain by-products are obtained which represent particular parts or compounds of the grain or seed. Whenever the methods of manu- facture are such as not to injure the palatableness or healthfulness of these waste products, they may be utilized as cattle foods. As a matter of fact, a large proportion of our commercial feeding stuffs is of this general kind and because these materials differ greatly in composition and nutritive value, the purchaser should clearly understand their source and character. Changes in methods and new manufacturing enterprises are constantly modifying the composition of old products aud introducing new ones, consequently the facts as they exist at one time may not be applicable for a long period. There is need therefore of constantly keeping informed in regard to the various cattle foods found in the markets, if they are to be economically purchased and wisely used. (227) 228 The Feeding of Animals CLASSES OF COMMERCIAL BY-PRODUCT FEEDING STUFFS For the purposes of description, the various by- product feeding stuffs may be classified according to their origin. Their sources are mainly as follows: 1. The milling of wheat and other grains. 2. The manufacture of oatmeal and a variety of breakfast foods. 3. The manufacture of beer and other alcoholic drinks. 4. The manufacture of starch and sugars, chiefly from corn . 5. The extraction of oils, chiefly linseed oil and cottonseed oil. Wheat offals. — No commercial feeding stuffs are regarded with greater favor, or are more widely and largely purchased by American feeders than the by- products from milling wheat. Wheat -bran and mid- dlings are cattle foods of standard excellence, whether we consider composition, palatableness or their relation to the quality of dairy products. These feeding stuffs consist of particular parts of the wheat kernel, a knowl- edge of the structure of which aids greatly in under- standing what they are and why they possess certain chemical and physical properties. To ordinarj^ observation the wheat grain appears to be merely a seed, but it is really a seed contained in a tightly - fitting seed -pod. This pod, which is woody and tough, constitutes the outer coating of the kernel. On the seed itself are two more hard and resisting coat- ings, one of which is double, that* serve to protect the Structure of the Wheat Kernel 229 softer parts. We find, then, that in every wheat ker- nel there are three coats entirely unlike the rest of the grain, because they consist of hard, thick- walled cells containing but little starch, if any, with a much larger proportion of cellulose or fiber than is found in the inner portion of the kernel. Figs. 4 and 5. Just inside the innermost of the three outer coats is a layer of material very rich in protein compounds, Fig. 4. Section of entire wheat kernel (enlarged 16 diameters). 1, Seed pod and seed coatings. 4, Gluten layer. 5, Mass of starch cells. which may properly be called the gluten layer. The great bulk of the wheat kernel is made up of cells closely filled with starch grains. This is the soft white portion of the seed and is that which furnishes the flour. All of these parts serve to protect, and, in ger- mination, to nourish the essential portion of the seed, the germ or embryo which lies "at the lower end of the 230 The Feeding of Animals rounded back of the kernel." Bessey, in an admirable description of the wheat kernel, tells us that the per- centage proportions of its various parts are as follows: Per cent Coatings 5 Gluten layer 3-4 Per cent Starch cells 84-86 Germ 6 We are now prepared to understand the significance of the statement that in milling wheat the flour of Fig. 5. Partial section of wheat kernel (enlarged 155 diameters). 1. Seed pod. 3. Inner seed coat. 2. Outer seed coat. 4. Gluten cells. 5. Starch cells. various grades comes from the starch cells, the other portions passing into the bran, shorts and middlings, which collectively are termed the offal. If only the coatings, gluten layer and germ went to make up the offal it would include only about 14 or 15 per cent of the kernel, the flours taking the remainder, but, as a matter of fact, no milling methods so far used com- pletely separate the starch cells from the enclosing tissue, so that the offal is perhaps never less than 25 per cent Offals from Milling Wheat 231 of the whole grain. In milling tests conducted by the Minnesota Experiment Station, the offal from several lots of wheat, good and bad, varied from 25 per cent to 40 per cent. If four bushels of wheat are consumed per capita by the population of the United States, which is below the estimate, and if only one-quarter of this is converted into offals, the amount of bran and middlings annually consumed by our domestic animals is 2,250,000 tons, barring the quantity which may be exported. It is a fact worthy of special comment that because of a somewhat irrational standard of excellence for bread, certain parts of the wheat kernel best adapted to the nourishment of young and growing animals are separated with great care to be used by the brute life of the farm rather than by the farmer and his family. A comparison of the composition of the whole wheat kernel, white flour and the various parts of the offal emphasizes this point. The figures given are taken from the results of an investigation by Snyder, of Minnesota, in which he compared the composition of different grades of wheat with that of the flour and products obtained from them: Composition of tcheat and its milling products (per cent) Water Ash — Protein — « Total Gluten Fiber Nitrogen- free extract Starch and dex trine Pat Wheat kernel. . 10.2 1.8 13.7 13.5 3.2 69. 64.9 2.0 Wheat flour — , 10.6 .4 11.2 11. 77.3 70.4 .5 Wheat germ . . . 10.4 2.7 15.7 15.3 67.7 3.5 Wheat shorts . . 10.1 3.1 13.1 12.9 5.4 65.3 2.9 Wheat bran. . . . 10.4 5.9 15.4 14.8 10.2 52.9 5. 232 The Feeding of Animals The greater richness of the coatings of the kernel in mineral matter, protein, fiber, and oil is made plain by this comparison. There is four times as large a percentage of mineral matter and of oil in the whole wheat as in the flour, nearly one -third more protein and considerably less starch. On the other hand, the bran is not less than ten times richer in mineral com- pounds and oil than the flour, one -third richer in pro- tein, with correspondingly less starch. "Graham" flour, which contains more or less of those parts which pass into the offal in milling white flour, does not differ so much from the whole kernel. Middlings differ from bran in containing less of the hard, tough coatings and more of the finer parts of the kernels, and this feed- ing stuff varies from the coarser kinds to the fancy middlings, according to the proportion of starchy ma- terial present. Red Dog flour is counted among the offals from milling wheat, and it represents the dividing line between the middlings and the high-grade flour. There is a belief more or less prevalent that bran from the old milling processes which contained more of the starchy part of the kernel than is now the case, was more valuable than roller process bran is. It is probable that a greater proportion of starch in- creases the digestibility of bran, and in this sense the old process bran was superior to the roller process product; but, on the other hand, the latter is more nitrogenous than the former and is therefore more effi- cient as a protein supplement to home -raised foods. Residues from breakfast foods. — In the manufacture of breakfast foods, the use of which has become so By -products from Oats 233 prevalent, certain by-products are obtained which are now found in the market as cattle foods. The prepa- ration of oatmeal and similar materials involves the selection of the finest oat -grains, i. e., those having the largest kernels, from which the hulls are removed. These hulls and the smaller oat -grains, and perhaps bran, constitute by-products which, after being finely ground, are sold as oat -feed and in various mixtures. Fig. 6. Section of entire oat grain (enlarged 16 diameters). 0. Hull. 1. Seed coat. 4. Gluten layer. 5. Mass of starch cells. As the sale of oat hulls as such, or in a fraudulent way when mixed with other substances, is likely to occasion a financial loss to feeders, it is desirable to clearly understand the situation. We shall accomplish this by a study of the relation of the oat hulls to the kernel in quantity and composition. Figs. 6 and 7. It is common knowledge that the oat -grain con- sists of a hull and kernel, which are easily separated. The former is fibrous and tough, and the latter soft with very little fiber. The hull forms a considerable portion of the grain. In 1894, the Ohio Experiment 234 The Feeding of Animals Station made a study of numerous varieties of oats. It was found that with sixty -nine varieties the hulls constituted from 24.6 per cent to 35.2 per cent of the whole grain, the average being 30 per cent. It did not appear, contrary to the general opinion, that the proportion of hull was larger with light oats than with heavy, although observations elsewhere have sustained the popular view. At the Mustiala Agricultural Col- lege twenty -eight samples of Finnish oats and twenty samples from five other counties gave from 28 to 32 per cent of hulls. Wiley states that the average propor- tion of hull to kernel is as three to seven, which varies with the locality in which the oats are grown. The figures in the next table show the composition of the dry matter of whole oats, oat hulls and the hulled kernel : Nitrogen- free Ash Protein Fiber extract Fat % % % % % Whole oats, 30 samples 3.4 13.2 10.8 67. 5.6 Hulls, New Jersey 7.2 3.5 32. 56.3 1. Hulls, Vermont 6.9 4.4 29.5 57.2 2. Hulls, Wisconsin 7.8 2.3 50.1 39. .8 Hulled kernels, 179 analyses . 2.3 15.4 1.5 72.1 8.7 The inferiority of the hulls as compared with the whole grain or with the hulled kernels is very appa- rent, because of their smaller proportion of protein and oil and their much larger percentage of fiber: If hulls are purchased at all the price should be on a par with that at which the coarsest and cheapest grades of fodders are sold, and the surprisingly prevalent dis- honest adulteration of ground whole grains with oat Residues from Barley and Com 235 ^f^&0ii '~7H hulls should in some way be prevented by official in- spection. Farmers will do well to carefully inquire into the character of the so-called oat feeds and mixed feeds offered to them. These articles are often oat hulls, poor oats and other refuse mixed with corn or with by - products of an- other class and are dis- tinctly inferior to the whole grains. Such low grade mixtures are not wisely purchased at prices nearly equal to those rul- ing for whole cereal grains of any kind. Other grains besides oats are used as the source o f specially prepared human food. Barley feed, a by - product from the manufacture of pearled barley, like oat feed con- sists of the hulls and por- tions of the grain and contains more fiber and less starch than the origi- nal grain, its value being proportionately less. Hominy is made from corn and consists of the hard portions of the kernel, leaving as a residue the hull, germ, and part of the starch cells, which collectively are sold as hominy feed or chop. This differs from the whole kernel but little in composition and is practically as digestible. Fig. 7. Partial section of oat grain (enlarged 170 diameters). 0. Hull. 4. Gluten cells. 1. Seed coat. 5. Starch cells. 236 The Feeding of Animals Brewers 1 by -products. — Sugar in some form is at present essential to the production of alcoholic bev- erages, a cheap supply of which is obtained by con- verting the starch of certain cereal grains into maltose, which afterward passes into fermentable sugars. This result is accomplished by placing barley and other grains under such conditions of moisture and tempera- ture that they germinate. We have already seen that during germination the starch of a seed is converted into maltose through the action of a diastatic ferment, and the maltster arrests this germination at a point which gives the maximum quantity of sugar. The malted grains^ are subsequently dried and the sprouts after removal appear in our markets in an air -dry con- dition, constituting one of our valuable nitrogenous feeding stuffs. The malted grains are then crushed, the sugar is extracted from them, and the residue is known in commerce as brewer's grains, a by-product feeding stuff fairly rich in protein. The high propor- tion of protein is due to the fact that the starch has been partially used up, leaving the other constituents behind in a more concentrated form. These grains are mostly dried and may then be shipped to distant mar- kets in a perfectly sound and healthful condition. Residues from starch and glucose manufacture. — Within a comparatively recent time the gluten meals and feeds have assumed an important place among our commercial feeding stuffs. These materials and others bearing related names vary within wide limits in texture and composition, and concerning their quali- ties and value there has existed among the farmers Structures of the Maize Kernel 237 much confusion of thought. Even the best informed have not always been promptly cognizant of new products of this class or of changes in the compo- sition of older ones, so rapidly have new methods of manufacture developed. The gluten meals, gluten feeds, corn bran, and the like are residues obtained in the manufacture of starch and glucose from the maize kernel. This kernel, like Fig. 8. Section of entire maize kernel (enlarged 10 diameters). 1. Outer layer of husk or skin. 2. Inner layer of skin. 4. Gluten layer. 5. Mass of starch cells. that of wheat, is not homogeneous in structure and composition, a condition which makes it possible, through mechanical or chemical operations, to secure a variety of by-products greatly unlike in texture and in their proportions of nutrients. All this is made plain through a consideration of the structure of the maize kernel. This seed is in some respects similar to that of wheat. We have first an outside husk or skin made up of two distinct layers, one less than we find in wheat. This skin is rich in 238 The Feeding of Animals fiber, scarcely any being found in the other portions of the kernel. Next on the inside is a layer of cells rich in gluten. The body of the kernel surrounding the germ or embryo consists of closely compacted starch cells, though some of this interior tissue on the sides of the kernel next to the walls is flinty. We may property speak of the maize kernel, then, as consisting of four parts, — the husk, the gluten layer, the germ, and the starchy and hard part. Figs. 8 and 9. At the New Jersey Experiment Station 100 grains of the maize kernels were separated as nearly as possible into the skin, germ, and main or starchy and hard portions. These parts were analyzed, and below are given the results: Composition of dry substance of maize kernel (per cent) Nitrogen- free Proportion Ash Protein Fiber extract Fat of parts Original kernel 1.7 12.6 2. 79.4 4.3 100. Skin 1.3 6.6 16.4 74.1 1.6 5.5 Germ 11.1 21.7 2.9 34.7 29.6 10.2 Starchy and hard part . .7 12.2 .6 85. 1.5 84.3 These figures are essentially similar to those obtained by other investigators, including Salisbury, Atwater, and Balland. The separation of starch cells from other parts of the kernel is now accomplished mechanically. Either before or after soaking in warm water, the maize ker- nels are crushed into a coarse powder. The various parts separate in water by gravity, the hulls floating on the surface and the germs sinking to the bottom. The starch and harder portions of the kernel remain By-products from Maize Kernel 239 in suspension in the water, which is conducted slowly through long troughs, where the starch settles to the bottom and the more glutinous portions float off and are recovered. It is now easy to see how these various by- products may differ widely. When made up largely of the hulls or bran they are characterized by a relatively Fig. 9. Partial section of maize kernel (enlarged 170 diameters). 1. Outer layer of skin. 2. Inner layer of skin. 4. Gluten cell. 5. Starch cells. high proportion of fiber with comparatively low per- centages of protein and fat. The presence of the germs increases the relative amount of protein some- what and of the fat very greatly. The fine glutinous part, that is finally separated from the starch, when unmixed with other materials is distinguished by its high content of protein. As found in the market, the principal brands are "sugar corn" or "starch" feed, made up mostly of hulls and germs; gluten meal, that comes from the flinty portion of the kernel, and gluten feed, which is now a 240 The Feeding of Animals mixture of hulls and the gluten part. When unmixed with other parts of the kernel, the hulls are also known as corn bran and the germ portion from which the oil has been pressed is called, when ground, germ oil meal. The corn bran contains the least protein and the gluten meal the most, while the gluten feed and germ oil meal occupy a position between these. It should be remarked that the commercial names for gluten prod- ucts are not always a safe guide in their purchase. Residues from the manufacture of beet sugar. — An industry apparently now on the increase in the United States, the manufacture of beet sugar, is offering to farmers two waste products, sugar beet pulp and sugar beet molasses. The former is the extracted beet tissue from which all the sugars and more or less of other soluble compounds have been removed. This pulp as it leaves the factory has been found to contain an average of scarcely 10 per cent of solids. One ton of pulp supplies, then, not over two hundred pounds of total dry substance, or perhaps one hundred and sixty pounds of digestible dry substance. This means that it would require six tons of pulp to supply as much of digestible nutrients as one ton of good hay. The solids of the pulp must be regarded as inferior to those of the beets before extraction, because consisting more largely of fiber and gums whose productive value is below that of sugar. Experiments at Cornell University indicated that the pulp is worth about one- half as much as corn silage, which would be approximately the proportion of digestible matter in the two materials. Sugar beet pulp is, however, a useful, succulent Residues from the Oil Seeds 241 food, and may be fed to advantage in quantities from seventy-five to one hundred pounds daily to full-grQwn animals, provided it can be purchased at a price pro- portional to its value. The pulp is not adapted to transportation for long distances because of the heavy expense of freight and handling, but is most available for consumption near the factories. It may be preserved in pits or silos. The molasses is generally four-fifths or more dry substance and contains from 40 to 50 per cent of sugar, which is all digestible and which gives to this product its only value for feeding purposes. This material has been fed successfully to bovines and swiue. When given as an addition to coarse foods and home -raised grains it obviously should be combined with some nitrogenous feeding stuff like gluten meal or the oil meals. The oil meals in general. — Materials of this class may properly be regarded as among the standard feed- ing stuffs. Because of their uniformity in quality and composition, their general usefulness in compounding rations and their value in maintaining soil fertility, their use has had the sanction of scientific men and of successful practice. The oil meals are so called be- cause they are the residues left after the extraction of the oil from certain seeds and nuts, among which are cottonseed, flaxseed, hemp and poppy seed, rape seed, sesame seed, sunflower seed, cocoanuts, palm nuts, peanuts, and walnuts. Of the residues from these sources, those from cottonseed and flaxseed are most common in the United States; in fact, no 242 The Feeding of Animals other oil meals have become important in our cattle feeding. A description therefore of the production of cottonseed meal and linseed meal will not only cover the points of practical interest to American feeders, but will serve to illustrate the main facts that pertain to the manipulation of these oil seeds. It uiay be stated in a general way that two methods are used for removing vegetable oils from seeds, expressing bj r pressure and extraction with a solvent, both of which are now in use. In using the first method, it was formerly the custom to express the oil from the cold crushed seed, but now the seed is more generally submitted to heat, either by boiling or steaming, afterwards applying the pressure to the warm material. More oil is obtained by the latter process. The second or extraction method involves the use of a solvent, gen- erally a light naphtha, which leaves less oil behind than either cold or warm pressure. Before extraction the crushed seed is heated just as when pressure is used. Cottonseed meal. — The cottonseed as gathered from the plant consists on the exterior of a mass of long white fibers that are attached to the outer coat or hull, inside of all of which is the kernel or meat. The seed is first delinted by running it through a gin, which removes the lint or cotton of commerce. After this operation there is still attached to the seed a soft down, which is subsequently removed and which constitutes what is known as "linters," a short lint that is used in making cotton batting. The remaining portion is that from which cottonseed oil and certain by-product feeding stuffs are produced. Cottonseed By-products 243 The first process in the manufacture of the oil is to remove the hull from the inside meat. This is done by a sheller, which breaks the seed -coat and forces it from the kernel. These seed -coats, which constitute from 45 to 50 per cent of the delinted seeds, are known in commerce as cottonseed hulls, and are used to some extent as a feeding stuff. They are characterized by a very low proportion of protein and a very high con- tent of fiber. Twenty -two analyses show a range of protein from 1.6 per cent to 4.4 per cent, and of fiber from 35.7 to 66.9 per cent. Such material as this be- longs with the very lowest grade of coarse fodder, as both composition and experience demonstrate. The hulless kernels make up from 50 to 55 per cent of the delinted seed, and from those the oil is obtained. These meats are first cooked twenty or thirty minutes in large, steam -jacketed kettles in order to drive off the water and render the oil more fluid, and then after being formed into cakes in wire cloths, they are sub- mitted to a pressure of 3,000 to 4,000 pounds to the square inch. This removes at least four -fifths of the oil and leaves the cakes very solid, which after dry- ing are cracked and then ground into a fine meal, known in commerce as cottonseed meal. Formerly a ton of ginned seed yielded the following quantities of the different parts: Linters 20 pounds Hulls 891 ' ' Cake or meal 800 " Crude oil , 289 " Since the above estimate was prepared the manufac- 244 • The Feeding of Animals turing process has been so improved that from forty to forty -five gallons of oil are now obtained from a ton of seed, giving a correspondingly smaller amount of cake. Chemists are well aware that cottonseed meal at the present time is less rich in oil than was the case a few years ago. When we learn that no less than 1,500,000 tons of cottonseed are worked annually at oil mills, which in- volves the production of about 600,000 tons of meal, we realize the importance of this by-product feeding stuff, and the future possibilities are seen in the fact that only about one -third of the seed now grown finds its way to the oil mills. The composition of the cotton oil by-products may properly be stated in this con- nection : Nitrogen- free Water Ash Protein Fiber extract Fat % % % % % % , 9.9 4.7 19.4 22.6 24. 19.4 Cottonseed hulls. . .11.4 2.7 4.2 45.3 34.2 2.2 Cottonseed kernels . 6.9 6.9 30.3 4.8 21.4 29.6 Cottonseed cake. . . 8.6 7. 44.1 4.9 21.2 14.2 These figures represent the composition of the several materials when the separations are fairly complete. Cottonseed products are sometimes sold, however, in a more or less mixed condition. There has been found in the market undecorticated cottonseed meal, or the meal with all the hulls ground in without removal from the seed. Practically all the meal found in the markets now is the decorticated, or that free from hull. This should be light yellow in color and have a slightly nutty flavor. It should show few or no black Linseed Meal 245 specks, because the presence of these indicate either accidental or intentional adulteration with hulls. Cot- tonseed feed, which appears to have found only a limited use, is a finely -ground mixture of cottonseed hulls and cottonseed meal, and its value is usually much less than that of the pure meal. Linseed meal (oil meal) . — The original source of this feeding stuff is the flax plant. This plant serves a very useful purpose in producing a valuable fiber, an oil which now seems indispensable as a constituent of paint and a high class stock food. Flaxseed, of which the annual production in this country averages about twelve million tons, contains a very high per- centage of oil, ranging in the analyses so far made from 22 to 40 per cent. The average is variously stated by different compilers at from 33 to 37 per cent, and the mean of these two numbers is probably fairly correct. On this basis a bushel of flaxseed, weighing fifty -six pounds, contains nineteen and one -half pounds of oil and thirty -six and one -half pounds of other substances. Linseed oil is obtained from the seed by both the pressure and extraction methods. The oldest method was to subject the cold crushed seeds to a heavy pres- sure, which expressed from 70 to 80 per cent of the oil, leaving a cake containing from 10 to 15 per cent. Later the warm pressure process was introduced, which consists of moistening the crushed seed, heating it to from 160° to 180° Fahr., and submitting it to a pressure of 2,000 to 3,000 pounds per square inch. This im- provement increased the output of oil from a given 246 The Feeding of Animals quantity of seed, the amount expressed being about 90 per cent of the whole, leaving a cake containing from 6 to 7 per cent. The latest and most effective process is the extraction of the oil by a light naphtha. The seed is crushed and heated as in the warm pres- sure method, and the oil is then extracted by repeated teachings with naphtha until the residue when dry contains only about 3 per cent of oil. The naphtha is thoroughly driven from this residue with steam so that the resulting meal is entirely free from odor and is as palatable as the residue from the pressure process. The terms "old process" and "new process" are now applied to linseed meal, the former referring to that made by the cold and warm pressure processes and the latter to the residue from naphtha extraction. The composition differences between the two is seen in the following average of several analyses of each kind which were made by Woll : Water % Ash % Protein % Nitrogen- free Fiber extract % % Fat % Old process linseed meal. . 9.4 5.4 35.6 7.1 35. 7.5 New process linseed meal. . 9.2 5.4 36 6 8.6 37. 3.2 These averages show 1 per cent more protein and 3 per cent less fat in the new process meal. The old process samples analyzed by Woll were doubtless from the warm pressure methods and do not fairly represent the linseed which was found in the markets when it first came into general use. Four hundred and twenty -eight analyses of old process cake compiled by Dietrich and Konig, which were made pre- vious to 1888, show an average of only 28.6 per cent Linseed Meal 247 of protein and 10.6 per cent of fat. An average by the same authors of 179 analyses of the meal shows 30 per cent of protein and 9.9 per cent of oil, those samples taken previous to 1880 being poorer in pro- tein and richer in fat than those analyzed after that date. The average of twelve samples of linseed cake made prior to 1883 and compiled by Jenkins, gives 29.7 per cent of protein and 11.2 per cent of fat. There is no question but that the meal now found in the markets is considerably richer in protein and poorer in fat than that with which American farmers were first acquainted. The relative values of the old and new process meals are much discussed. Many farmers are preju- diced in favor of the former, possibly because any- thing which has been treated chemically is regarded with suspicion when considered as a food. No good evidence exists, however, that new process meal is less palatable or less healthful than the old process prod- uct, nor has practice demonstrated that in a general way it is less nutritious. A very useful inquiry by Woll into the charac- teristics of the two kinds of meal showed certain differences which are interesting in this connection. Two points were studied : the digestibility and the property of swelling to a mucilaginous condition when stirred up with water. Experiments with animals both in Germany and in this country have shown a quite uniformly lower coefficient of digestibility for the pro- tein of the new process, than for the old process, meal. Woll tested this matter by artificial digestion with a 248 • The Feeding of Animals solution of pepsin, and his results verified those se- cured with animals, the protein of the old process samples proving to be 10 per cent the more soluble. This difference is believed to be caused by the addi- tional cooking with steam which attends the driving out of the naphtha from the new process meal, for it seems to be well proven that the digestibility of vege- table protein is diminished by cooking. American experiments do not indicate a lower digestibility of total dry matter for the new process meal, which is contrary to the verdict of German digestion trials. The property of swelling to a mucilaginous condi- tion is one well known to pertain to flaxseed. This is due to mucilage cells found in the seed -coat. When this mucilaginous matter has once been swollen, it will not repeat the process after drying. Woll's tests showed that the old process meal responded to the swelling test, but not the new process, a result due probably to the steam cooking of the latter. This may serve as a means of determining the method used in manufacturing a given lot of meal, but probably has no special significance as to feeding value, unless it indicates the new process meal to be less useful in making a porridge for feeding calves CHEMICAL DISTINCTIONS IN CATTLE FOODS The classes of cattle foods as arranged in the pre- vious discussion have had reference to several factors, chiefly those relating to origin and texture. Chemical facts have not been considered in these divisious. There How Cattle Foods Differ 249 are, however, certain chemical differences among the various groups of feeding stuffs, a knowledge of which is helpful in selecting materials for compounding rations. Coarse foods vs. grains and grain products. — In com- paring hays, straws, and other fodders with grains and grain products there are points of chemical un- likeness which bear an important relation to problems of nutrition. In the first place, the nitrogen com- pounds differ. In the grains we find the nitrogen combined mostly in the form of albuminoids, while in the fodders a proportion of it, and sometimes quite a large one, exists in amides. This is a point in favor of the grains, for, as we have seen, the nutritive function of amides is probably more limited than that of albuminoids. Again, the non -nitrogenous material of the grains is in general superior to that of the her- baceous cattle foods. In the former, especially in the cereal grains, there is but little fiber and the nitrogen- free extract is made up largely of starch and other bodies, whose net value in nourishing an animal is quite surely greater than that of fiber and gums found in such abundance in the hays and other fodders. The work of digesting fiber and gums is greater than with sugar or starch, and of the digested material from the former we cannot affirm an equal value with that coming from the more easily soluble carbohydrates. In short, the terms protein and nitrogen -free extract do not signify the same compounds or the same values when applied to different feeding stuffs. Classification according to the 2^oportions of nu- trients. — The relative proportion of nitrogenous and 250 The Feeding of Animals non -nitrogenous compounds in feeding stuffs is greatly varied. There is no fixed proportion in the same spe- cies, even, but it varies to some extent with the season, period of cutting, and other conditions. At the same time, there are differences of composition between several groups of feeding stuffs that are constant within not very wide limits, and which it is important to recognize. There are a few terms that are popularly used to differentiate feeding stuffs which are misleading. For instance, corn meal is often spoken of as "carbona- ceous" in contrast to cottonseed meal, which is called "nitrogenous." It may be seen by reference to pre- ceding data that there is a higher proportion of carbon in albuminoids than in starch or sugars. Cottonseed meal is more carbonaceous than corn meal, rather than less so. Such a distinction is therefore absurd. "Heat forming" is another term often applied to foods rich in carbohydrates, while the more highly nitrogenous materials are characterized as "muscle forming," a distinction apparently based upon the facts that carbohydrates are usually largely burned in the animal body, and that albuminoids are the only source of the muscle compounds. But, as a matter of fact, the potential heat value of the digestible part of an oil meal is certainly as great as that of digestible corn meal. Under certain conditions one feeding stuff is no more fully, used than the other for tissue -forming purposes, and both may be wholly utilized in the pro- duction of some form of energy, ultimately heat, the potential value of the oil meal being no less in this respect than that of the corn meal. Classes of Feeding Stuffs 251 The satisfactory division of feeding stuffs into as few as two classes, according to their composition, is not possible by the use of any terms whatever. Such a division is necessarily based upon the relation in quantity of the protein to the non- nitrogenous part, and there is an almost uniform gradation of foods in protein content from those containing the least to those most highly nitrogenous. Any division into groups with reference to the percentage amount of protein must be entirely arbitrary and should take account of at least four classes of materials, other- wise the extremes of each division are too widely apart. Probably no more convenient and rational class- ification of grains and grain products can be suggested than the one proposed by Lindsey: Class I. Thirty to 45 per cent protein, 30 to 45 per cent carbohydrates. The oil meals and gluten meals, the latter of which are represented by the Chicago, King, Cream, and Hammond. Class II. Twenty to 30 per cent of protein, 60 to 70 per cent carbohydrates. Gluten feeds, in- cluding the Buffalo, Golden, Diamond, Daven- port, Climax, Joliet, and Standard as now made, Atlas meal, dried brewer's grains, malt sprouts, buckwheat middlings, and beans and peas. Class III. Fourteen to 20 per cent protein, 70 to 75 per cent carbohydrates. Wheat brans and mid- dlings, rye bran, mixed feeds or any mixtures of oat feed reinforced by more highly nitrog- enous material. 252 The Feeding of Animals Class IV. Eight to 14 per cent protein, 75 to 85 per cent carbohydrates. Barley, corn, oats, rye, wheat, cerealine, hominy, oat feeds, corn and oat chop, and corn bran. The hays and other fodders properly belong with Class IV. By reference to these groups it is possible to ascer- tain about what place a particular feeding stuff will take in making up a ration, for instance, to what ex- tent it will serve as a protein amendment to a mixture of materials composed largely of carbohydrates. FOODS OF ANIMAL ORIGIN The principal materials of animal origin that are used in feeding domestic animals are milk, dairy by- products and offals from slaughter-houses. They are mostly characterized by their large relative proportion of protein and their high rate of digestibility. The net nutritive value of their solid matter is very high, because it is practically all utilized and a minimum amount of energy is required for its mastication and digestion. Practice has long recognized the peculiar efficiency of feeding stuffs of this class, which is due to the directs available forms of the nutrients. Milk. — Whole milk has a greatly varying food value according to its proportion of solid matter. Its com- position is determined by several factors. The milks of different species of domestic animals are greatly unlike both in their proportions of total solids and in the relation in quantity of the different constituents. The table of composition of the milk of several Milk of Various Species 253 species, including human milk, given herewith, is taken mostly from figures given in Richmond's Dairy Chem- istry : Composition of the milk of mammals (per cent) Species Water Dry matter Ash Casein Albumin Sugar Fat Bitch 75.44 24.54 .73 6.10 5.05 3.09 9.57 Ewe 79.46 20.56 .97 5.23 1.45 4.28 8.63 Sow 84.04 15.96 1.05 7.23 3.13 4.55 Goat 86.04 13.96 .76 3.49 .86 4.22 4.63 Cow*.. 87.10 12.90 .70 3.20 5.10 3.90 Woman 88.20 11.80 .20 1. .50 6.80 3.30 Mare 89.80 10.20 .30 1.84 6.89 1.17 The milks are arranged in the order of their rich- ness, the dry matter present varying from 24.54 per cent to 10.20 per cent. Those containing a high pro- portion of total solids, particularly those from the bitch and the ewe, are especially rich in proteids and fat, the percentages of sugar being less than half those in the poorer milks. It is noteworthy that the pro- portions of proteids and fats in the milk decrease, and the percentage of sugar increases, as the total solids diminish. Two -thirds of the solids of mare's milk is sugar, the proportion of this constituent in the dry matter of a ewe's milk being only about one -eighth. If we assume that the milk of each species is best adapted to its own progeny, it follows that when the young of other species is fed the milk of the cow, as is so often done, this milk should be modified so far as possible to simulate that provided under natural conditions. When, for instance, cow's milk is fed to * Van Slyke. 254 ' The Feeding of Animals a colt, it should be diluted and have its content of milk sugar increased; or when lambs are given cow's milk it may well be made richer, by the addition of cream, perhaps. The milk of the cow varies with the breed, the individual and the period of lactation, and in its use for feeding purposes these variations should be considered. While we have little or no data on the subject, it is probable that the same causes op- erate in affecting the milk of all species. Dairy by-products. — These by-products are three in number, skim -milk both from the gravity and the separator processes, buttermilk, and whey. Their aver- age composition, as taken from compilations by several authors, is as follows: Composition of dairy offals (per cent) Total Casein and Water solids Ash albumin Sugar Fat Skim-milk, general average, Cooke... 90.25 9.75 .80 3.50 5.15 .30 Skim-milk, gravity, Fleischman 89.85 10.15 .77 4.03 4.60 .75 Separator-milk, Richmond 90.50 9.50 .78 3.57 4.95 .10 Buttermilk, Cooke 90.50 9.50 .70 3. 5.30* .50 Buttermilk, Vieth 90.39 9.61 .75 3.60 4.06t .50 Whey, Cooke 92.97 7.03 .60 .93 5. .50 "-They, Van Slyke 93.07 6.93 .60t .83 5.16 .34 Skim -milk and buttermilk are not greatly unlike in richness in solid matter or in general composition. In case the skim -milk is sweet, buttermilk differs from it because in the latter the sugar has changed partially or wholly to lactic acid. Whey is considera- bly poorer in solids than the other dairy by-products and also differs from them in the proportions of the several constituents. * Probably includes the lactic acid, t.80 per cent lactic also present, t Assumed. Dairy By-products as Foods 255 Skim -milk is the residue left after removing the cream. It differs in composition according to the composition of the original whole milk and the thor- oughness of the creaming. The percentage of solids which it contains is proportional in a general way to the richness of the whole milk. At one time a con- trary notion prevailed and the skimmed milk of the butter breeds, especially the Jersey and the Guernsey cows, was popularly supposed to be of inferior quality. Numerous analyses have been made of this by-product from several breeds, and the succeeding figures give the proportion of solids and fat in skimmed milk from the gravity process: Skimmed milk Solids in Total whole milk solids Fat % % % Holstein 12.22 9.50 .52 Ayrshire 12.98 10.40 .85 Jersey 15.24 10.50 .37 These figures show most clearly that the Jersey product is more valuable than that from Holstein cows, volume for volume. Skim -milk is also affected by the manner or thor- oughness with which the cream is removed. The more perfectly the fat is taken out the less the percentage of solids left behind and the less their unit value as a source of energy. For these reasons gravity process skimmed milk is often more valuable for feeding than that from the separator, though under the best con- ditions of skimming in both cases the difference is small. Buttermilk, which is the residue after extracting 256 . The Feeding of Animals butter from cream, varies in composition from such causes as the composition of the cream and the per- fectness of the churning. The more fat is left in it the more it is worth for feeding purposes. Its feeding value is but little less than that of skim -milk. Whey solids are mostly sugar. In good cheese- making practice, whey retains scarcely any of the casein and fat of the milk. It therefore takes a place in the ration quite different from that of skim -milk, as it is essentially a carbohydrate food. The dairy offals are peculiarly valuable as food for young animals and swine. It is safe to say that for calves and pigs no other sufficiently inexpensive materials can fully take their place in their relation to health and vigor. Slaughter-house and other animal refuses. — The offals from slaughter-houses and from fish, which have a somewhat limited use in feeding domestic ani- mals, are meat scraps, meat meal, dried blood, and dried and ground fish. The accompanying analyses display their composition, which is subject to great variations : Composition of slaughter -house and other refuses {per cent) Water Ash Protein Fat Animal meal, N. Y. station. . 2.2 Meat meal, German analysis. . 10.7 Fish scrap, German analysis. 13.9 Dried blood, Henry 8.5 The meat and fish offals vary greatly according to proportion of bone which they contain. The percen- tage of protein is always large, nevertheless. Dried 38.7 37.5 13.2 4.1 71.2 13.7 31.3 48.4 6.4 4.7 84.4 2.5 Feeding Stuffs of Animal Origin 257 blood is much less rich in mineral matter and fat than other slaughter-house offals are generally, and the proportion of protein is correspondingly larger. All these materials are excellent poultry foods when used as a part of the ration. They may be fed to swine also as an amendment to cereal grains when dairy by-products are not available. Q CHAPTER XVII THE PRODUCTION OF CATTLE FOODS The farmer, in deciding what forage and grain crops he shall grow, should take into consideration several factors, of which the following are the main ones: (1) the adaptability of the various crops to the soil and climate; (2) the adaptability of the various crops to the kind of business which is to be followed, whether dairying, stock- growing or sheep husbandry; (3) the capacity of the various crops for the produc- tion of digestible food; (4) the protein supply; (5) the maintenance of fertility. 1. Concerning the adaptability of crops to the great variation of soil and climate in this country, it is not possible to treat extensively in this connection without going too fully into questions of agricultural botany. There are, however, a few general facts worthy of men- tion. In the first place, few farmers have accurate information concerning the species of grasses w T hich are growing on their farms. Only occasionally is one found who carefully observes what species are most prosperous under his conditions. This is equivalent to the statement that but little attention is given to the matter of the adaptability of forage plants to the environment under which they must be grown. While (258) The Selection of Crops 259 it may be said that nature carries on for the farmer more or less of a selective process, it must be remem- bered that the rotation of crops, involving of necessity an artificial selection of species, interferes with this process. The old practice of maintaining mowing fields for ten to twenty years without breaking the sod might allow the grasses most congenial to the soil and climate to establish themselves, but successful farming on this basis is now scarcely possible. It is essen- tial, therefore, especially in dealing with meadows and pastures, to know what members of the grass family or other forage plants find the environment congenial. It is commonly remarked, with much reas6n, that more is to be gained by the proper selection and proper care of the forage crops which have maintained suc- cessful, though perhaps unrecognized, existence among us for years, than by seeking for better results from some introduced species. No cultivated plant pos- sesses qualities that will defend the farmer against the evil effects of poor or ill-directed culture, and when intelligent, thorough methods prevail, many of the familiar species will do for us all we can reasonably expect. Occasionally an introduced species may serve a useful purpose, as is true of alfalfa, but in general a more economical production of cattle foods will be reached most surely through an improvement of meth- ods in growing what we already have. 2. It is obvious that the home production of feed- ing stuffs must be adapted to the kind of stock kept. A herd of good dairy cows can hardly be most suc- cessfully managed on the old basis of exclusive pastur- 260 The Feeding of Animals ing in the summer and exclusive dry food in the winter. To attain the best results the pasture must be amended by soiling crops, at least during late sum- mer and early autumn, and a succulent food is a de- cided improvement to a winter ration. On the other hand, the successful growing of steers, sheep or horses requires in many localities only a good pasture and plenty of dried fodder and grain, although some suc- culent foods are desirable with any class of animals. Every feeder, no matter what his line of business, should have at command quite a variety of fodders. 3. The productive capacity of the different crops used as cattle foods is greatly unlike. A satisfactory crop of maize or alfalfa contains greatly more dry matter per acre than one of oats, peas, or any of the usual meadow grasses, and in order that land may yield a maximum supply of feeding stuffs it is neces- sary to step outside grass and grain farming, where long rotations are practiced and where a major part of the farm is kept in meadow grasses and only small areas are devoted to cultivated crops. Rapid rota- tion and the use of the more grossly feeding crops are necessary to a vigorous development of the re- sources of any land for the maintenance of animal husbandry. Other things being equal, the most desirable crop is the one producing the largest amount of digestible dry matter. This will not be the same crop for all localities. In one section it may be maize, in another alfalfa, or in another roots. The selection must be determined by circumstances, and no rule of general Productive Capacity of Different Crops 2G1 application is possible. Of course, other things out- side of quantity of production are not generally equal. The cost of production varies so that the largest yield- ing crop is not necessarily the most economical. This is a local matter also, concerning which no safe gen- eral statement can be made. It would be convenient if some correct, universal standards of production and cost could be formulated for the guidance of farmers, but both growth and cost are much modified by lo- cality and other circumstances, and data are not avail- able, and doubtless never will be, from which useful averages may be obtained. The most that it is possible to show is the rela- tive productive capacity of different crops when the yield is what is regarded as highly satisfactory in fa- vorable localities under good culture. This is done in the accompanying table. Attention is again called to the fact that judgment should be based upon the amount of digestible dry matter produced : Dry Digestible Yield Dry mat- dry per acre matter ter matter fresh ma- Dry per digesti- per terial matter acre ble acre lbs. $ lbs. lbs. Alfalfa 35,000 25 8,750 69 5,162 Maize, whole plant 30,000 25 7,500 61 5,025 Red clover, about 3% tons new hay.. 18,000 30 5,400 57 3,070 Oats and peas 20,000 16.2 3,240 65 2,106 Timothy, about 2% tons new hay.... 11,500 38.4 4,416 57 2,517 Hungarian grass 19,000 25 4,750 67 3,182 Mangolds 60,000 10 6,000 88 5,200 Sugar beets 32,000 20 6,400 88 5,632 Potatoes 18,000 25 4,500 85 3,825 The estimates here given may not coincide with the views of all as to what constitutes a fair crop, but 262 The Feeding of Animals from the data shown, any one can easily make a cal- culation on the basis of his own estimate. The foregoing figures emphasize the relative high productivity of alfalfa, maize and roots, as compared with certain cereal grains and the meadow grasses. The former crops fill an important place in intensive stock husbandr}'. Probably no species of forage plants are known that are more economical sources of high class cattle food than alfalfa and maize. While no more productive than mangolds and sugar beets when these are at their best, the former cost much less in labor. Crops of such large productive capacity are espe- cially adapted to dairymen located on limited areas of high-priced land. They occupy a place in intensive culture which will become more and more important as grazing and long rotations are replaced by soiling and stable feeding during the entire year. 4. The protein supply of the farm may be aug- mented by the growth of leguminous crops, such as peas, beans, alfalfa and the clovers. In so far as climate and soil permit the economical production of this class of fodders, there will be a correspondingly less neces- sity for the purchase of nitrogenous feeding stuffs. 5. The leguminous crops are regarded as sustaining an important relation to fertility in acting as nitrogen- gatherers, and for this reason they are believed to be a valuable adjunct of any system of farming. Just what proportion of the nitrogen in a crop of clover, for instance, comes from outside the soil is not known, however, either for particular conditions or as to the average . Importance of Soiling Crops 26'S SOILING CROPS The production of green crops as an amendment to the pasture, or as a substitute for it, is a practice essen- tial to the highest success in dairyiug on many farms, and is to some extent desirable in other branches of stock husbandry. There are few pastures, perhaps none, that afford grazing in August and September of such a quality as to maintain a satisf acton 7 flow of milk. In many instances, moreover, farmers owning a limited area of high-priced tillable land wish to keep the maximum number of animals per acre, and to do this they must cultivate soiling crops for stable feeding. It is no longer a debatable question, whether or not soiling is profitable under most conditions. Unlimited testimony can be furnished showing the great gain from every point of view of even partial soiling as an amendment to the pasture. Whether soiling should be substituted entirely for grazing is a business matter which should be decided according to the conditions involved. New England farmers owning upland rocky pas- tures in which grow native grasses of the highest quality for any class of animals could not wisely dis- card them. Such land generally absorbs but little cap- ital, and the labor of supplying food by this method is reduced to a minimum. The case is different with high-priced, easily tilled land located near good mar- kets. These conditions call for intensive farming, and grazing animals on permanent pastures is not a part 264 • The Feeding of Animals of intensive practice. Under such circumstances the wisdom of a soiling system is clearly indicated. In the first place, much more food is produced per unit of area by soiling than by pasturage. Armsby found that two soiling crops in one season, for instance, rye followed by corn, yielded five times as much diges- tible organic matter as pasture sod, when the whole growth on the latter was plucked without waste, the quantities being, respectively, 5,845 pounds and 1,125 pounds. It is variously estimated from observations in practice, that three to five times as many animals can be supported on a given area by soiling as by grazing. Again, grazing is wasteful because of the imperfect consumption of the growth that is made. Much grass is tramped down and much is fouled with dung and urine. These facts are well understood. Other advan- tages besides economy of land and material pertain to soiling, such as saving of fences, comfort of the ani- mals and an increased supply of manure, but these factors do not require discussion in this connection. Outside of considerations previously noted, produc- tiveness especially, the dairy farmer in selecting soiling crops must have regard chiefl}' to the number of ani- mals to be fed, the time when the crops will be needed, and the number of days required for their develop- ment. If soiling is adopted in order to amend the pasture during the late summer and early fall a lim- ited number of crops will meet the demand. Three sowings of peas and oats in late May and early June and two plantings of corn, one at the usual time and Kinds and Succession of Soiling Crops 265 one two weeks later, would furnish a supply of green food when it is most likely to be needed. If it is a question of selecting crops for a system of complete soiling, nothing more suggestive can be offered as to species and succession than schemes prepared by Phelps for Connecticut, and by Voorhees for New Jersey : Connecticut scheme Approximate Species of crop Time of seeding time of feeding Winter rye Sept. 1 May 10-20 Winter wheat Sept. 5-10 May 20- June 5 Clover July 20-30 June 5-15 Grass (from meadows) June 15-25 Oats and peas April 10 June 25-July 10 Oats and peas April 20 July 10-20 Oats and peas April 30 July 20-Aug. 1 Hungarian June 1 Aug. 1-10 Clover, rowen Aug. 10-10 Soy beans May 25 Aug. 20-Sept. 5 Cow peas June 5-10 Sept. 5-20 Rowen grass (meadows)-. Sept. 20-30 Barley and peas Aug. 5-10 Oct. 1-30 New Jersey scheme Approximate Species of crop Time of seeding time of feeding Winter rye Sept. May 1-10 Winter wheat Sept. May 10-20 Crimson clover Sept. May 20 June 1 Oats and peas April 1 June 1-10 Oats and peas April 10 June 10-20 Mixed grasses Sept. June 20-30 Oats and peas May 10 July 1-10 Cow peas May 20 July 10-20 Corn June 1 July 20-Aug. 1 Japanese millet June 20 Aug. 1-10 266 The Feeding of Animals New Jersey scheme — continued Approximate Species of crop Time of seeding time of feeding Cow peas June 10 Aug. 10-20 Corn June 20 Aug. 20-Sept. 1 Soy beans July 10 Sept. 1-10 Japanese millet July 20 Sept. 10-20 Corn July 1 Sept. 20-Oct. 10 Barley and peas Aug. 10 Oct. 10-20 Barley and peas Aug. 20 Oct. 20-30 The schemes are not practicable for all sections of the United States. In the southern and western states more especially, they would need modification to suit local conditions. Alfalfa is not included in either of the foregoing lists. For all sections where this plant can be grown successfully it takes first rank as a soiling crop. In portions of New York, for instance, in favorable sea- sons it can be cut continuously from about the middle of May until late in September, and no other crop is more thoroughly relished by horses and cattle. It is valuable for horses, even when they are doing hard work. The area devoted to soiling crops must be deter- mined by the number of animals and the productive- ness of the land which is to be used. Voorhees states that seven acres devoted to the succession of crops which he recommends will supply twenty* -five cows from May 1 to November 1. This estimate would hold only when two and three crops are grown on the same land in a single season, which requires a generous use of manure or of commercial fertilizers, or of both. The following are suggestions of possible rotations: Rotations of Soiling Crops 267 {Winter rye, or crimson clover Oats and peas Soy beans {Oats and peas Japanese millet Barley and peas J Winter rye, or winter wheat (Corn {Winter wheat Cow peas Japanese millet {Oats and peas Cow peas Barley and peas Crimson clover Corn Some writers estimate the needed area of soiling crops on the basis of one -quarter to one -half a square rod per day for each full-grown animal, the smaller unit applying to corn and the larger to oats and peas, and similar crops. All this must be a matter of judg- ment based upon the circumstances involved. CHAPTER XVIII THE VALUATION OF FEEDING STUFFS It seems to be very generally supposed that it is possible to state fixed relative money values for feed- ing stuffs, and that by comparing these with market prices the relation of value to cost may be ascertained. Such a state of knowledge is certainly much to be de- sired, for it would be of great practical use to feeders. For various reasons, however, it is not yet attained, and there is little present prospect that it will be. The establishment of such relative values for cattle foods, as a whole and for general use, is a much more complex matter than many suppose it to be, for it touches on one side some of the most profound prob- lems of physiological chemistry, concerning which we have only partial knowledge. The problem of assigning values to the classes of nutrients in feeding stuffs may be approached from two directions; viz., from the commercial side and from the physiological side. In the first case, the effort would be to calculate on the basis of the prices of standard commercial feeds, what is the actual pound cost of each of the classes of nutrients, and thus have a means of ascertaining whether a particular «feed is selling for less or more than the existing market con- (268) Calculating Values of Feeding Stuffs 269 ditions warrant. In the second case, the attempt would be to determine the relative physiological importance of digestible protein, carbohydrates, and fats, and this being done, the relative agricultural values of feeding stuffs would be established on the basis of their com- position and digestibility, thus providing purchasers with a guide for selecting the materials costing the least in proportion to their value. COMMERCIAL VALUES Experiment stations have for many years published relative commercial valuations of the various brands of fertilizers that are in the market. Why are we not able to follow the same course with cattle foods ? Sim- ply because of existing conditions. The dry matter of cattle foods is made up of ash, protein, carbohydrates, and fats. We practically ignore the ash and base the value of a given food upon the other three classes of compounds, which are the same in number as the three useful ingredients of mixed fertilizers. Now if we could find in the market a cattle food supplying only a single ingredient, as is the case with fertilizers, we could from its composition and market price determine the cost of this ingredient. As a rule, however, these classes of nutrients must be bought in a mixed condi- tion. All commercial cattle foods, except, perhaps, one waste product from sugar production, are mix- tures in varying proportions of protein, carbohydrates, and fats. When we buy one we buy all three. Pro- tein, starch, sugar or oils as found in commerce have 270 The Feeding of Animals become, through the necessary processes of separation, too costly to be considered for cattle -feeding purposes, and their prices in these forms are not a proper basis of calculation. If, therefore, a farmer pays $15 for a ton of wheat bran, what proportion of this sum shall he assign to the 320 pounds of protein, the 1,240 pounds of carbohydrates, or the 84 pounds of fats? Commercially considered our problem is complex, and no simple process will solve it. If we were to determine what is the cost of one pound of dry matter through the simple division of the price of a ton of feed by the pounds of dry matter which it contains, and then declare that all forms of dry matter have equal cost, we would get as many prices for protein and starch as there are commercial feeds, with no dis- tinction as to the money value of these nutrients. Such a method would be absurd. It would be a bare assumption to declare that all the compounds of a food should have equal market cost. An attempt was made in Germany, and to some extent in this country, to calculate by the "method of least squares " what should be considered the cost of protein, carbohydrates, and fats as based upon the ton prices of a variety of feeding stuffs. Valuations so derived appeared to find favor for a time, and some of our experiment stations, following the lead of Ger- man chemists, published pound prices for the three classes of nutrients, and calculated what commercial cattle foods should cost when valued on a common basis. It was soon found, however, that, mathemati- Inaccuracies of Money Valuations 271 cally as well as practically, most absurd results were obtained. In the first place, it is already demonstrated that the money valuations are often greatly influenced by the choice of feeds which shall enter into the calcula- tion. Penny, in New Jersey, using cottonseed meal, bran, middlings, cobmeal, corn meal, and oats, ob- tained certain values for protein, carbohydrates, and fats. Hill shows that if Penny had left out the cob- meal the value for fat would be only half that found, and the value of the protein and carbohydrates would be a quarter more. Woll obtained certain pound prices with a list of common feeds, but Hill shows again that if Woll had left out rye bran these prices would be greatly changed. It appears that varying individual judgments as to the list of feeds which shall determine values maj' cause absurd differences in the calculated market cost of the nutrients, and introducing into the list or withdrawing from it a comparatively unim- portant feeding stuff may lower or raise the price of one nutrient even one -half. A still more serious difficulty arises from the fact that often when an apparently typical and proper list of feeds is used from which to calculate prices, the use of the method of least squares results in giving a negative value to one of the nutrients. In several cases of this kind the fat was shown to be worth less than nothing, a most absurd conclusion. This mathe- matical method is, therefore, not available for the valuation of feeding stuffs, and so far no mathema- tician has offered one that is. 272 The Feeding of Animals PHYSIOLOGICAL VALUES We are left now to inquire whether we ma}' not use physiological values, in other words the work which a nutrient will perform in the animal body, as a start- ing point from which to calculate relative values. If, for instance, it could be demonstrated that protein has a fixed physiological value twice, and fats three times, that of carbohydrates, it would then be a very simple matter to ascertain what proportion of the cost of a ton of cottonseed meal should be applied to each class of nutrients. To illustrate, a ton of average cotton- seed meal contains about 590 pounds of carbohydrates, 860 pounds of protein, and 260 pounds of fat. If these ingredients are assumed to have a ratio of value of 1, 2, and 3, then the whole would be equivalent to 3,090 units of carbohydrates, the cost of one unit of which would be .8 cent, when we pay $25 per ton for the cottonseed meal. On this basis it would be necessary to assign to the protein a cost of 1.6 cents per pound, and to the fats 2.4 cents. If our premise were correct we could calculate the cost of the nutrients in any one of the feeding stuffs, and could either ascertain which was the cheapest source of each in- gredient, or by averaging could establish a basis for a general valuation. Unfortunately no such a premise can be correctly formulated. We are not yet wise enough to establish fixed relative physiological values for the three classes of nutrients. It may be asked, do we not know the heat value of a unit of each of the nutrients, of protein, of starch, Physiological Values not Definite 273 and of fat ? We probably do. These values have been found with apparent accuracy. Why, then, may we not establish the relative, value of the nutrients on the basis of their potential energy, which is meas- ured by the heat they produce upon combustion ? Sim- ply because foods have another function beside fur- nishing motive power to the animal and keeping him warm. They act as building material. The pro- tein and fat of milk and of the body tissues are de- rived from the food compounds, and the actual rela- tive value of these compounds for constructive pur- poses is not yet known. No one has yet succeeded in actually determining the relative money value of pro- tein, carbohydrates and vegetable fats as fat producers, and we have no data that allow a definite conclusion concerning the comparative money worth of the muscle- forming function of protein as against the fat -forming function of starch. There is no promising prospect, at present, of being able to compare foods on the basis of their physiological importance as a means of deter- mining what should be the relative market cost. SELECTION OF FEEDING STUFFS What useful knowledge is available to the stock- feeder as a means of guiding him to an economical selection ? In the first place, the feeder may know the composition of feeding stuffs. If he cares to be intelligent in his business he will know that some feeds carry more nitrogenous matter than others; he will be aware that all the cereal grains contribute to R 274 The Feeding of Animals the ration much the same compounds in much the same proportions, and he will understand the varia- tions of composition among the waste products that are in the market as commercial feeds. He will learn how the coarse foods differ among themselves and from the grains. Practice and observation will teach him that some feeds are better adapted than others to a certain class of animals, even though of essentially the same composition. In his efforts to compound rations he will not only have regard for this adapta- tion, but he will keep in mind what practice and sci- ence have taught concerning the mixtures necessary to secure an efficient combination of nutrients for the work to be done. After all this is understood, there may be several feeds which are essentially alike in composition and nutritive function but which have different prices, and there still remains the problem of selecting the most economical. If a feeder wishes for carbohydrates, from what source should he purchase them ? If he needs protein should he select gluten meal, one of the oil meals, or some other of the nitrogenous by- products ! It is clear that the best he can do is to select the feeds that supply the largest quantity of available nutrients for the least money. If all the feeding stuffs were digested in equal proportions there would be no need of considering digestibility, but this is not the case. Large differences in digestibility exist. From 86 to 88 per cent of the dry matter of the cereal grains, oats excepted, is dissolved by the diges- tive juices, while the solubility of wheat bran, brewer's Selecting Feeding Stuffs 275 grains, and oat feeds is on the average only about 62 per cent. Oats are nearly one -fourth less digestible than corn, barle} r or rye. The refuse products known as the oil meals are less digestible than the gluten feeds and meals, due, doubtless, to the hulls contained in the former. These facts are important and affect the nutritive value of commercial feeds very materially. Farmers should base their judgment of the value of feeding stuffs primarily upon the proportions of digestible dry matter which they contain. This method will probably allow the closest approximation to rela- tive values of any. It is certainly more accurate than a comparison of the proportions of total dry matter. A hundred pounds of corn contains even less dry matter than the same weight of oat feed, but the di- gestible material of the former is over 30 per cent in excess of that in the latter. It is to be remembered, however, that comparisons of this kind can only be instituted between feeding stuffs of the same class. The relative values of oil meal and corn meal cannot be ascertained in this way, neither can those of tim- othy hay and corn meal. We should not pay for oil meal and corn meal on the basis of the quantities of digestible nutrients w T hich they furnish, because the nutrients are not identical in the two cases. Diges- tible material, which is 40 per cent protein, cannot be measured by digestible material, which is only 10 per cent protein. Neither can we so compare timothy hay and corn meal, for while the proportions of protein and non- protein compounds may not be so very differ- ent in the two, the nitrogen -free compounds are 276 The Feeding of Animals greatly unlike and may have unlike physiological values, as we have seen. The following table shows the digestible material in 100 pounds of various feeding stuffs, as calculated from average composition and digestibility. In the case of hays the water content is assumed to be uni- form; viz., 12.5 per cent, while the percentages given for the grains are the averages found by analysis: Class I— Dried grass plants Corn fodder, dent Corn fodder, flint, , Corn fodder, sweet , Corn stover Hungarian hay Oat straw , Orchard grass hay Red top hay , Timothy, all Timothy, in bloom or before Timothy, after bloom Class II— Dried legumes Alfalfa Clover, alsike Clover, red Clover, white , Class III— Cereal grains Barley Corn meal Corn and cob meal Oats Oat feed Rye meal Per cent of digestibility of dry matter 64 68 67 57 65 50 57 60 53 61 53 59 58 57 67 86 88 79 70 62 87 Pounds dry matter in 100 of the feeding stuff 60* 60* 60* 60* 87.5 90 87.5 87.5 87.5 87.5 87.5 87.5 87.5 87.5 87.5 89 85 85 89 92 88 Pounds digestible dry matter in 100 of feeding stuff 38.4 40.8 40.2 34.2 56.9 45 49.9 52.5 46.4 53.4 46.4 51.6 50.8 49.9 58.6 76.5. 74.8 67.1 62.3 57 76.5 *Assumed. Selecting Feeding Stuffs 277 Pounds Per cent of Pounds dry digestible digestibility matter in dry matter of dry 100 of the in 100 of matter feeding stuff feeding stuff Class IV— Nitrogenous feeds 16-30 per cent protein Brewer's grains 62 92 57 Gluten feed 86 92 79.1 Malt sprouts 67 90 60.3 Wheat bran 62 88 54.5 Wheat middlings 75 88 66 Pea meal 87 90 78.3 Class V— Nitrogenous feeds 30-45 per cent protein Gluten meal 90 92 82.8 Linseed meal, O. P 79 91 71.9 Linseed meal, N. P 80 90 72 Cottonseed meal 74 92 68 It is fully recognized that these figures cannot be taken as absolute relative values. Feeding stuffs bear- ing the same name are not always exactly similar in composition or in equally good condition. Variations in the moisture content occur, especially with the coarse fodders. Even after allowing for all these factors, results will not follow exactly the quantities of diges- tible matter supplied, because there seems to be a greater adaptability of some feeds to the needs of a particular species. Nevertheless we are forced to con- clude that food materials of the same class must fur- nish energy and building material in proportion to what is digested from them. OTHER STANDARDS OF VALUATION Certain writers and speakers base the value of ni- trogenous feeding stuffs, from bran up, entirely on the 278 The Feeding of Animals protein content, and they divide the price by the pounds of protein in a ton in order to determine the relative economy of purchasing this or that material, and the feeding stuff in which the protein cost is the least when so reckoned is regarded as the economical one to purchase. This method seems to be absurd, for it is an assumption that the nutritive value of the carbohydrates and fat in commercial foods may be ignored. The argument is that the farm furnishes carbohydrates in abundance, and that commercial products should merely serve the purpose of rein- forcing the protein supply. If the carbohydrates of the farm have no selling value then this argument has some force, but this is ordinarily not the case. When starch and similar compounds must be pur- chased as a necessary accompaniment of protein, thus causing a surplus of carbohydrate food, certainly hay, oats, corn, barley, or some other home product may be sold to relieve this surplus. Many practical feeding experiments have been con- ducted for the purpose of comparing the different grain products as foods for the various classes of animals. Useful facts have been reached in this way, especially as the greater adaptability of some materials than others for a particular species. But experiments of this kind cannot be relied upon to fix relative values of feeding stuffs for milk production, beef production or for any other purpose. This is so, first of all, because the errors of such tests are so large that we cannot re- gard their apparent outcome as establishing constants. Again, the problems involved are too complex and the Inaccurate Standards of Valuation 279 effect of a given ration too dependent upon variable conditions, to allow logical conclusions from such ex- perimental data. The difficulties of the situation will be made clear to any one by a careful study of the whole mass of data resulting from feeding tests. Differences appear, some of which are consist- ently in one direction, especially in comparing nitrog- enous with carbohydrate foods, but as between mate- rials of the same class their comparative values as indicated bj r different experiments are greatly variable, even contradictory. Any one who endeavors to reach fixed and universal valuations on an experimental basis of this kind will find himself involved in hope- less confusion. Once in a while some one talks wildly about leaving food valuation to the "old cow." It is sometimes con- sidered a telling argument against the chemist's wis- dom to declare that he and the old cow do not agree. Certainly the cow knows better than the chemist what she likes to eat, and it is little use to offer her foods she does not relish. Even a chemist knows that. If, however, a dozen commercial feeding stuffs were spread around on a barn floor it would be much safer to trust an agricultural chemist, especially one experi- enced in stock feeding, to select a ration than any cow ever grown, — Holstein, Ayrshire, Jersey, long- horned, dishorned, or what not. The cow would prob- ably get at the corn meal and stay with it until well on the way to a fatal case of indigestibility. Her judg- ment is just about as good as that of a child with a highly cultivated "sweet tooth." CHAPTER XIX THE SELECTION AND COMPOUNDING OF RATIONS There are several factors that must be considered in selecting an efficient and economical ration, — factors which relate to both science and practice. It is gener- ally desirable that a food mixture shall be "balanced," but this gives, no assurance that a ration can be fed under particular conditions with satisfactory results. Intelligent observation in the barn or stable really takes the first place in formulating a method of feed- ing, which is supplemented to a valuable extent by the scientific insight of the chemist and physiologist. A ration may be chemically right and practically wrong, but, at the same time, it is worth much to the feeder to be assured that the nutrients which he supplies to his animals will meet their physiological ueeds. More- over, commercial relations such as the prices of feeds must be considered, and this is a business question and not a scientific matter. 1. A successful ration must be palatable. An agreeable flavor is not a source of energy or of build- ing material, but it tends to stimulate the digestive and assimilative functions of the animal to their high- est efficiency, and is a requisite for the consumption of the necessary quantity of food. Common experience (280) Palatableness and Adaptability of Ration 281 teaches that when cows or animals of any other class do not like their food, they "do not do well." Per- sons sometimes claim that they have contracted dys- pepsia by eating food which is not relished, even food that is nutritious and well cooked, and which would be entirely satisfactory to other individuals. The situ- ation is still worse when the food is undesirable both as to texture and flavor. We have reason to believe that animals are susceptible to the same influences as man, though perhaps not to the same extent. An ani- mal is more than a machine, and is possessed of a nervous organism, the existence of which should never be ignored. One way of stimulating an animal's appetite is to feed a variety of materials. Continuous feeding on a single coarse food and one grain is not conducive to the best results. The various available fodders and grains should be so combined as to allow the feeding of all of them throughout the season and avoid the exclusive use of one or two kinds for any extended period of time. The skilful feeder, then, will not fail to make the ration as palatable as possible, and will always consider the idiosyncrasies of appetite of each animal. 2. The ration must be adapted to the species. This is obvious as relates to quantity, but is equally true of the kinds of materials. For instance, both poultry and swine generally eat cottonseed meal with reluctance and with danger to health. Wheat bran is less de- sirable for swine than for other species. The horse and the hog are not adapted to rough fodder as are 282 The Feeding of Animals the ruminants. It is useless, however, to mention at this point other instances of this character, or to com- ment on their importance, further than to emphasize the foolishness of trying to bring all species of animals to a common basis in the supply of feeding stuffs. 3. The physiological requirements of the animal must be considered. A ration of maximum physio- logical efficiency and economy must contain the several nutrients in such quantities and proportions as will meet the needs of the particular animal fed, without waste. This statement is based upon facts given else- where in this volume relative to the demands of the animal body- and the functions of the nutrients. It remains now for us to consider how to compound such rations as are desired, or those that are adapted in kind and quantity to the requirements which they are to meet. Obviously, the first essential for doing this is the adoption of standards to which rations should conform, for if we do not have these there is no possibility of concluding whether one food mixture is better or worse than another for a particular pur- pose. Such standards have been proposed, which we knew first as German feeding standards. As found in the tables published by German authors, they are the result of numerous and elaborate studies of the bal- ance of loss or gain to the animal organism when rations of various kinds were fed to animals at rest, at work, and when producing meat, wool or milk, in desirable quantities. They relate entirely to physio- logical demands without reference to the cost of the Feeding Standards 283 rations or to the profits which may result from their use. These standards take account of two main factors: (l).the quantity of available nutrients, and (2) the relative proportions of the classes of nutrients. Quan- tity is an essential consideration, for it is obvious that enough energy and building material must be supplied to do a given work. It is also obvious that quantity must be a variable factor according as the animal is large or small, doing hard or light work, giving much or little milk, or fattening rapidly or slowly. Account must be made of the proportions of the nutrients, because protein, for instance, has peculiar functions which other nutrients cannot exercise, and less than a certain minimum of the proteids would limit production by just the amount of the deficiency. In order for the protein to serve its maximum useful- ness its energy should not be encroached upon to fill a place equally well or better taken by carbohydrates; consequently, the proportion of carbohydrates must also be considered. The relative proportion of the nutrients of a ration we speak of as the nutritive ratio. By this term is meant the relation in quantity of the digestible pro- tein to all the other digestible organic matter reck- oned in terms of carbohydrates. If we multiply the quantity of fat by 2.4 we get its carbohydrate equivalent, and if we add this product to the quantity of carbo- hydrates present as such we have the carbohydrate value of the digestible matter other than the protein. This sum divided by the number representing the pro- 284 The Feeding of Animals tein gives the nutritive ratio. For instance, in a ration mentioned later there are .94 pound protein, 9.65 pounds carbohydrates, and .49 pound fat. (.49X2.4 -+- 9. 65)-h. 94 = 11.5. 1:11.5 is therefore the nutritive ratio of the ration. A nutritive ratio may be designated as "narrow," "wide," or "medium." These terms do not represent exact limits, to which there is universal agreement. A narrow ratio is one where the proportion of protein is relatively large, not less perhaps than 1:5.5. A wide ratio is one where the carbohydrates are very greatly predominant, or in larger proportion perhaps than 1:8.0. Anything between 1:5.5 and 1:8.0 may properly be spoken of as a medium ratio. For the purpose of illustration a few feeding stand- ards are given in this connection. These are selected from standards proposed by Wolff, as modified by Lehmann. (See full table in appendix.) They refer in all instances to animals weighing 1,000 pounds: For 1,000 pounds Jive weight daily Total Diges- Diges- diges- Dry tible tible Diges- tible Nutri- sub- pro- carbohy- tible organic tive stance tein drates fat matter ratio lbs. lbs. lbs. lbs. lbs. Cow, yield milk, 22 lbs... 29 2.5 13 .5 16 1:5.7 Fattening steer, 1st per. . . 30 2.5 15 .5 18 1:6.5 Horse, medium work 24 2. 11 .6 13.6 1:6.2 These and other standards will be discussed later when we come to consider the feeding of the various farm animals. Our present purpose is simply to make clear the steps necessary to bringing the quantity and Calculation of Standard Rations 285 composition of the ration into conformity with the standard selected. As a means of showing the steps involved in cal- culating what a ration is, and how to improve it if necessary, we will assume that it is desired to learn whether a food mixture which a milch cow is eating is what it should be, and if it is not, how to make it so. The standard ration for a 1,000-pound cow, giving twenty -two pounds of average milk, expressed in terms of water -free nutrients, has been given in the preceding table. The first point which requires our attention is that this standard is mainly expressed in terms of water - free digestible nutrients. This means that we must take into account the composition and digestibility of the particular feeding stuffs which enter into a ration if we would discover what it really is supplying of available food compounds. It is evident that usually feeders cannot have their cattle foods analyzed, and so they must resort to the tables of averages of com- position and digestibility, which are, or may be, in the hands of every farmer. But what figures shall be selected for use ? As we have learned, feeding stuffs, especially fodders, differ within quite wide limits in what they contain and in what the animal will dissolve from them, according to the stage of growth and con- ditions of curing, etc., and an average percentage of protein or an average coefficient of digestibility is likely to differ widely from the actual facts as per- taining to a particular material. All that can be done is to select as nearly as possible the figures which 286 The Feeding of Animals have been found for feeding stuffs in the condition of those which are to be fed. If the hay is from mature grass use the composition percentages and digestion coefficients given for such hay; if the silage is from mature corn, pursue a similar course in this case, and so on. Difficulty will be met in always finding suit- able figures, because without question there has been a failure to properly classify tables of composition and digestibility on the basis of the character of the ma- terials. The assumed ration which we wish to find out about consists of lbs. lbs. Late cut timothy hay. . 10 Hominy chops 2 Corn silage 25 Winter wheat bran .. . 3 The averages for composition and digestibility, which are as likely as any to represent these and other materials, are the following: -Composition « <— Digestibility— < a a) 2 a ® 2 © © ti o h Nutri- sub- Pro- Carbo- tive Kind of animal stance tein hydrates Fat Total ratio 1: lbs. lbs, lbs. lbs. lbs. Wool Breeds— continued Live weight Age in per head months lbs. 11-15 90 . . 22 1.8 11.2 .4 13.4 7. 15-20 100 . . 22 1.5 10.8 .3 12.6 7.7 Mutton Breeds 4-6 65 .26 4.4 15.5 .9 20.8 4. 6-8 85 . . 26 3.5 15. .7 19.2 4.8 8-11 100 . . 24 3. 14.3 .5 1.78 5.2 11-15 120 . . 23 2.2 12.6 .5 15.3 6.3 15-20 150 . . 22 2. 12. .4 12.4 6.5 GROWING-SWINE Breeding Stock 2-3 45 . . 44 7.6 28. 1. 35.7 4. 3-5 100 . . 35 5. 23.1 .8 28.9 5. 5-6 120 . . 32 3.7 21.3 .4 25.4 6. 6-8 175 . 28 2.8 18.7 .3 21.8 7. 8-12 260 . . 25 2.1 15.3 .2 17.6 7.5 Growing Fattening Animals 2-3 45 . . 44 7.6 28. 1. 35.7 4. 3-5 110 . . 35 5. 23.1 .8 28.9 5. 5-6 150 . . 33 4.3 22.3 .6 27.2 5.5 6-8 200 . . 30 3.6 20.5 .4 24.5 6. 8-12 275 . . 26 3. 18.3 .3 21.6 6.4 Fertilizing Constituents 439 4. FERTILIZING CONSTITUENTS OF AMERICAN FEEDING STUFFS This table is the one prepared by the Office of Ex- periment Stations, U. 8. Department of Agriculture, and published in the Handbook of Experiment Sta- tion Work, Bulletin No. 15. Green Fodders Corn fodder Sorghum fodder Rye fodder Oat fodder Common millet Japanese millet Hungarian grass (German millet) Orchard grass (Dactylis glomerata)* Timothy grass (Phleum pra- tense)* Perennial rye grass (Lolium perenne)* Italian rye grass (Lolium italicum)* Mixed pasture grasses . . Red clover (Trifolium pra- tense) White clover (Trifolium re- pens) Alsike clover (Trifolium hy- bridum) Scarlet clover ( Trifolium in- carnatum) Alfalfa {Medicago sativa) . oisture % Ash % Nitrogen % Phos- phoric acid % Potas- sium oxide % 78.61 4.84 .41 .15 .33 82.19 . .23 .09 .23 62.11 . .33 .15 .73 83.36 1.31 .49 .13 .38 62.58 . . .61 .19 .41 71.05 • • .53 .2 .34 74.31 • • .39 .16 .55 73.14 2.09 .43 .16 .76 66.9 2.15 .48 .26 .76 75.2 2.6 .47 .28 1.1 74.85 2.84 .54 .29 1.14 63,12 3.27 .91 .23 .75 80. • • .53 .13 .46 81. • • .56 .2 .24 81.8 1.47 .44 .11 .2 82.5 m # .43 .13 .49 75.3 2.25 .72 .13 .56 ♦Dietrich and Konig: Zusamensetzung und Verdaulichkeit der Futtermittei. 440 Appendix Moisture Ash % % Green Fodders— continued Cow pea 78.81 1.47 Serradella (Ornithopis sa- tivus) 82.59 1.82 Soja bean (Glycine soja) .73.2 Horse bean (Vicia fdba) . . 74.71 . . White lupine (Lupinus albas) 85.35 . . Yellow lupine (Lupinus lu- teus)* 83.15 .96 Plat pea (Lathyrus sylvestris)* 71. G 1.93 Common vetch (Viciasativa)* 84.5 1.94 Prickly comfrey (Symphy- tum asperrimum) .... 84.36 2.45 Corn silage . . _. 77.95 . . Corn and soja bean silage . 71.03 . . Apple pomace silage* . . . 75. 1.05 Hay and Dry Coarse Fodders Corn fodder (with ears) . . 7.85 4.91 Corn stover (without ears) . 9.12 3.74 TeosmteiEuchlamaluxurians) 6.06 6.53 Common millet 9.75 . . Japanese millet 10.45 5.8 Hungarian grass 7.69 6.18 Hay of mixed grasses . . . 11.99 6.34 Rowen of mixed grasses. . 18.52 9.57 Redtop ( Agrostis vulgaris) . 7.71 4.59 Timothy 7.52 4.93 Orchard grass 8.84 6.42 Kentucky blue -grass (Poa pratensis) 10.35 4.16 Meadow fescue (Festuca pra- tensis) 8.89 8.08 Tall meadow oat grass (Ar- rhenatcerum avenaceum) . 15.35 4.92 * Dietrich and Konig. Phos- phoric Nitrogen acid .27 1.19 .99 1.16 .1 .4 .32 Potas- sium oxide .31 .41 .14 .42 .29 .15 .53 .68 .33 1.37 .44 .35 1.73 .51 .11 .15 1.13 .18 .58 .59 1.19 .7 .42 .11 .75 .28 .11 .37 .79 .42 .44 .32 .15 .4 1.76 .54 .89 1.04 .29 1.4 1.46 .55 3.7 1.28 .49 1.69 1.11 .4 1.22 1.2 .35 1.3 1.41 .27 1.55 1.61 .43 1.49 1.15 .36 1.02 1.26 .53 9 1.31 .41 1.88 1.57 2.1 1.72 Fertilizing Constituents 441 Moisture Ash % % Hay and Dry Coarse Fodders— continued Meadow foxtail (Alopecurus pratensis) 15.35 5.24 Perennial rye grass . ... 9.13 6.79 Italian rye grass 8.71 Salt marsh hay 5.3b" Japanese buckwheat ... 5.72 Red clover 11.33 6.93 Mammoth red clover (Tri- folium medium) 11.41 8.72 White clover Scarlet clover* 18.3 7.7 Alsike clover 9.94 11.11 Alfalfa 6.55 7.07 Blue melilot( Melilotus cceruleus) 8.22 13.65 Bokhara clover (Melilotus alba) . . 7.43 7.7 Sainfoin (Onobrychis sativa) 12.17 7.55 Sulla (Jledysarum coro- narium) 9.39 . . Lotus villosus 11.52 8.23 Soja bean (whole plant) . 6.3 6.47 Soja bean (straw) .... 13. Cow pea (whole plant) . . 10.95 8.4 Serradella . 7.39 10 6 Scotch tares 15.8 . . Oxeye daisy ( Chrysanthe- mum leacanthemum) . . . 9.65 6.37 Dry carrot tops 9.76 12.52 Barley straw 11.44 5.3 Barley chaff 13.08 . . Wheat straw 12.56 3.81 Wheat chaff 8.05 7.18 * Dietrich and Konig. itrogen % Phos- phoric acid % Potas- sium oxide % 1.54 .44 1.99 1.23 .56 1.55 1.19 .56 1.27 1.18 .25 .72 1.63 .85 3.32 2.07 .38 2.2 2.23 .55 1.22 2.75 .52 1.81 2.05 .4 1.31 2.34 .67 2.23 2.19 .51 1.68 1.92 .54 2.8 1.98 .56 1.83 2.63 .76 2.02 2.46 .45 2.09 2.1 .59 1.81 2.32 .67 1.08 1.75 .4 1.32 1.95 .52 1.47 2.7 .78 .65 2.96 .82 3. .28 .44 1.25 3.13 .61 4.88 1.31 .3 2.09 1.01 .27 .99 .59 .12 .51 .79 .7 .42 442 Appendix Hay and Dry. Coarse Fodder s- continued Eye straw . . . Oat straw . . . Buckwheat hulls Moisture % 7.61 9.09 11.9 Boots, Btdbs, Tubers, etc. Potatoes 79.75 Red beets 87.73 Yellow fodder beets . . . 90.6 Sugar beets 86.95 Mangel -wurzels 87.29 Turnips 89.49 Rutabagas 89.13 Carrots . . . ^ 89.79 Grains and Other Seeds Corn kernels 10.88 Sorghum seed 14. Barley* 14.3 Oats 18.17 Wheat (spring) 14.35 Wheat ( winter) 14.75 Rye 14.9 Common millet 12.68 Japanese millet 13.68 Rice 12.6 Buckwheat 14.1 Soja beans 18.33 Mill Products Corn meal 12.95 Corn-and-cob meal .... 8.96 Ground oats 11.17 Ground barley 13.43 Rye flour ........ 14.2 Ash % 3.25 4.76 .99 1.13 .95 1.04 1.22 1.01 1.06 9.22 1.53 2.48 2.98 1.57 .82 4.99 1.41 3.37 2.06 Nitrogen % .46 .62 .49 .21 .24 .19 .22 .19 .18 .19 .15 1.82 1.48 1.51 2.06 2.36 2.36 1.76 2.04 1.73 1.08 1.44 5.3 1.58 1.41 1.86 1.55 1.68 Phos- phoric acid .28 .2 .07 .07 .09 .09 .1 .09 .1 .12 .09 .7 .81 .79 .82 .7 .89 .82 .85 .69 .18 .44 1.87 .63 .57 .77 .66 .85 Potas- sium oxide .79 1.24 .52 .29 .44 .46 .48 .38 .39 .49 .51 .4 .42 .48 .62 .39 .61 .54 .36 .38 .09 .21 1.99 .4 .47 .59 .34 .65 * Dietrich and KOnig. Fertilizing Constituents 443 Moisture Ash % % Mill Products — continued Wheat flour 9.83 1.22 Pea meal 8.85 2.68 By-products and Waste Materials Cora cobs 12.09 .82 Hominy feed 8.93 2.21 Gluten meal 8.59 .73 Starch feed (glucose refuse) 8.1 . . Malt sprouts 10.38 12.48 Brewers' grains (dry) . . . 6.98 6.15 Brewers' grains (wet) . . 75.01 . . Rye bran 12.5 4.6 Rye middlings* .... 12.54 3.52 Wheat bran 11.74 6.25 Wheat middlings 9.18 2.3 Rice bran 10.2 12.94 Rice polish 10.3 9. Buckwheat middlings* . . 14.7 1.4 Cottonseed meal 9.9 6.82 Cottonseed hulls 10.63 2.61 Linseed meal (old process) 8.88 6.08 Linseed meal (new process) 7.77 5.37 Apple pomace 80.5 .27 * Dietrich and Konig Nitrogen % Phos- phoric acid % Potas- sium oxide % 2.21 .57 .54 3.08 .82 .99 .5 .06 .6 1.63 .98 .49 5.03 .33 .05 2.62 .29 .15 3.55 1.43 1.63 3.05 1.26 1.55 .89 .31 .05 2.32 2.28 1.4 1.84 1.26 .81 2.67 2.89 1.61 2.63 .95 .63 .71 .29 .24 1.97 2.67 .71 1.38 .68 .34 6.64 2.68 1.79 .75 .18 1.08 5.43 1.66 1.37 5.78 1.83 1.39 23 .02 .13 INDEX Absorption of food, 119. Acids, 83; action on albuminoids, 65; action on carbohydrates, 86; fatty, 90; influence on digestion, 139. Age, influence on production, 411. Air, carbon in, 13; hydrogen in, 15; nitrogen in, 16; oxygen in, 14. Albuminoids, 57; action of acids and alkalies on, 65; action of heat on, 64; action of ferments on, 63, 65; com- parative energy values of, 173; com- pounds among, 57; energy of, 162; modified, 62. Albumins, 58; in milk, meat, eggs, 58; in plants, 59; properties of, 58; where found, 58. Alfalfa, as soiling crop, 266; produc- tivity of, 261. Alkalies, action on albuminoids, 65. Amides, 69; value of, 179. Animal, globulins in, 60; water in, 38. Animal body, distribution of ash com- pounds in, 49. Animal heat, source of, 9. Animal life, relation of oxygen to, 14; relation of plant to, 7; relation to man, 1. Animal meal. 256. Animals, composition of bodies, 93 ; mineral compounds in, 48; problems in feeding. '■',-. proportions of elements in, 22; selection of, 411; treatment of, 416. Ash, compounds of, 41; compounds in different species, 44 ; distribution compounds of in plants, 45; in ani- mal, 49; elements of, 30; influence of manufacturing processes on, 47; in plants, 43; variations in species, 43. Assimilation, definitions of, 99. Beef, feeding for production of, 339. Beet sugar, residues from manufacture of, 240. Bile, 115; function of, 116. Blood, 142; corpuscles in, 143; mineral compounds of, 50. Bone, formation of, 152. Bovines, maintenance food for, 297; maintenance rations for, 299. Butter-milk, 254, 255; as food for swine, 363. Breakfast foods, residues from, 232. Breed, influence on digestion, 138; in- fluence on production, 409, 411. Brewer's grains, 236; residues, 236. Butter, effect of foods on, 319. Calcium, sources of, 20; in nutrition, 20. Calf, growth of, 324; metabolism of, 324. Calorie, definition of, 161. Calorimeter, 162; respiration form, 201. Calves, composition of, 403; feeding of, 328; production with, 40-1, 405; skim- milk for, 329. Capillaries, blood, 119. Carbohydrates, 75; action of acids on, 86: action of ferments, 86; animal, 84; characteristics of, 85; energy of, 162; elements in, 30; functions of, 155; in- fluence of excess of, 135; relative en- ergy values of, 172; variations in di- gestibility, 123. (445) 446 Index Carbon, 12; in crops, 13; supply of, 12, 13. Carbonic acid, elimination of, 149. Casein, 66. Cattle foods, 203; chemical differences in, 248; classification of, 249; com- mercial, 227; production of, 258. Cellulose, 73 ; action of ferments on, 118 ; energy value of, 172. Chemical studies, knowledge from, 191. Chicks, food mixtures for, 396; rations for, 395. Chlorine, in nutrition, 19; sources of, 19. Coarse foods vs. grains, 249. Colts, feeding of, 333; foods for, 337; mixtures for, 338; oats as food for, 335. Combustion, measurement of, 200. Compounds, classes of, 28; elements in classes, 30. Cooking, influence on digestion, 132. Corn bran, 240. Cottonseed, 242; cake, 243; hulls, 243; meal, _'42; oil, 243. Cows, production with, 404, 405; selec- tion of, 409. Crops, carbon in, 13; forage, 204; legu- minous, 262; productive capacity. 260; soiling, 263; succession for soiling, 265. Crude fiber, 72; digestibility of, 124. Curing, changes in, 205; conditions of, 206; vs. ensiling, 217. Dairy by-products, 254. Dextrose, 82. Diastase, function of, 87, Digestibility, determination of, 139; in- fluence of combination of nutrients on, 135; conditions influencing, 126. Digestion, energy required for, 165; of food, 98. Dried blood. 256. Ducks, food mixtures for, 396; rations for, 395. Elements, chemical, of nutrition, 11; proportions in animals, 22; propor- tions in plants, 21; sources of, 12. Energy, available, 163; carbohydrates as source of, 155; expended by work horses, 369; fats as source of, 157; food as source of, 157; in various food compounds, 162; manifestations of, 159; measurement of available, 174; net, 164 ; of albuminoids, 173 ; of carbohydrates, 172; of cellulose, 172; of digested nutrients, 199; of fats, 173; of gums, 173; of ration, calcula- tion of, 198 ; protein as source of, 155; required for chewing, 165; source of, 8; unit of, 161; uses of , 157. Ensilage, 212; crops for, 218. Ensiling vs. field curing, 217. Enzyms, 103. Ether extract, 89; composition of, 92, digestibility of, 124. Ewes, feediug of, 331. Exercise, need of, 415. Extractives, 70; value of, 179. Fat, of milk, 91; study of formation, 195. Fats, 88; absorption of, 120; compara- tive energy values of, 173 ; digesti- bility of, 124; elements in, 30; energy of, 162; functions of, 157; influence on digestion, 137 ; neutral, 90 ; of body, source of, 154, 156; production value of, 176. Fattening, feeding for, 341, 351. Feces, 121. Feeding, frequency of, 134. Feeding animals, problems in, 3. Feeding standards, 282. Feeding experiments, utility of, 188. Feeding stuffs, classification of, 251; commercial, 227; commercial values of, 269; composition of, 419; digesti- ble substance in, 276; digestibility of, 427; energy of, 163; fertilizing con- stituents of, 439 ; physiological values Index 447 of, 272; popular valuation, 277; rela- tion to digestive processes, 121 ; selec- tion of, 273; valuation by cow, 279; valuation by experiments, 278; valua- tions of, 268; variations, water in, 37; water in, 36; water in air dry, 37; water in green, 36. Feeds, ash in, 47. Fermentations, in alimentary canal, 118. Ferments, 99; action on carbohydrates, 86; coagulating, 63; of digestion, 65; organized, 100; unorganized, 100,103. Fibrinogen, 61. Fish offals, 256. Fodders, dried, 205; green, 205. Food, absorption of, 119; digestion of, 98; distribution of, 142; influences on flavor of milk, 321 ; relation to growth, 324; relation to milk, 316; relation to production, 194, 400; units of value, 401; use of, 142, 147. Foods, of animal origin, 252. Forage crops, 204; for fattening sheep, 357; influence of stage of growth on composition, 209; influence of stage of growth on yield, 208; harvesting of, 207. Fowls, composition of bodies of, 387, 403; digestive apparatus of, 383; feed- ing of, 379; production with, 404, 405. Fruit sugar, 83. Gases, of digestion, 164. Gastric juice, 112. Gelatinoids, 68. Germ oil meal, 240. Globulins, 59; in animal, 60; in seeds, 59; properties of, 59. Glucose manufacture, residues from, 236. Gluten, energy of, 175; productive value of, 177. Gluten feed, 239. Gluten meal, 239. Glycogen, 84; formation of, 150. Grains (and seeds), 225. Grape sugar, 82. Grasses, 204. Grinding grains, influence on digestion, 133. Growing animals, feeding of, 324. Growth, relation to food, 325; sustained by plant, 8. Gums, energy value of, 173; digestibility of, 124; vegetable, 78. Hay, water in, 37. Heart, the, 144. Heat, body, regulation of, 168 ; effect on albuminoids, 64; effect on carbo- hydrates, 86. Hens, laying, rations for, 393. Hogs, fattening, growth of, 358. Horses, influence of speed on work of, 370; maintenance food for, 300; main- tenance rations for, 302 : work per- formed by, 368; working, feeding of, 367; working, foods for, 376; work- ing, food needs of, 371 ; working, rations for, 377 ; working, source of rations, 374. Hydrochloric acid, in stomach, 112. Hydi-ogen, 15; in air, 15; in water, 15; source to animal, 16. Intestinal juice, function of, 118. Intestines, the, 114. Investigation, methods of, 192. Iron, compounds of, 20; in nutrition, 20. Keratin, 69. Knowledge, sources of, 186. Lact-albumin, 59. Lacteals, 119. Lambs, fattening, experiments with, 353 ; feeding of, 331. Laws of nutrition, 182. Legumes, 204. Levulose, 83. Lime, in animal, 48 ; for poultry, 390 ; in plants, 45. 448 Index Linseed meal, 245 ; new process, 246 ; old process, 246. LinseeJ oil. 245. Liver, the, 150. Lungs, the, 146. Maintenance food for bovines, 297; for horses, 300. Maintenance rations, 295; for bovines, 299; for horses, 302; for poultry, 393; sources of, 296; uses of, 295. Maize, influence stage of growth, 211; productivity of, 261. Maize kernel, 237. Malt sprouts, 236. Maltose, 82. Man, relation to animal, 1. Mares, feeding of, 334. Matter, classes of, 26 ; combustible, 26; incombustible, 26; inorganic, 28; organic, 28. Meat, albumin in, 58 ; production of, 339. Meat meal, 256. Metabolic wastes, errors caused by, 136, 140. Milk, composi.ionof, 305; as cattle food, 252; demands for secretion of, 309; effect of food on, 313, 321; formation solids, 308; of various species, 253; production of, 304; protein needs for production of, 310; ration for produc- ing, 309, 312; secretion of, 306; source of solids, 307 ; sources protein in ration for, 313. Milk sugar, 85. Mineral compounds, elimination of, 149 ; function of, 152. Molasses, energy of, 175 ; production value of, 177. Mouth, the, 104. Mutton, production of, 349. Muscular power, source in plants, 9. Muscular tissue, 153. Mastication, energy requirements, 1C5. Nitrogen, 16; compounds, 16, 51; in air, 16; in soil, 16. Nitrogen-free compounds, 71. Nitrogen-free extract, 74; energy values of compounds, 171. Nuclein, 67: special value of, 180. Nutrients, combustion of, 147; energy relations of, 166; functions of, 151; physiological values of, 170; produc- tion values of, 175; relative energy values of, 171 ; storage of, 147. Nutrition, chemical elements of, 11; compounds of, 25; laws of , 182. Nutritive ratio, 283. ■» Oat feeds, 233; grain, 233; hulls, 233; kernel, 233. Oats, as food for colts, 335. Oils, energy of, 175; productive value of, 177. Oil meals, 241. Oils, the, 88. Ova- albumen, 59. Oxygen, 14; in air, 14; in earth, 14: in lungs, 146; in water, 14; relation to animal life, 14; relation to energy, 15; use of, 147. Oxen, fattening, experiments with, 343. Palatableness, importance of, 2S0; in- fluence on digestion, 126. Pancreatic juice, 117; function of, 117. Pectin bodies, 80. Pentosans, energy value of, 173. Pepsin, 113. Peptones, absorption of, 120. Phosphoric acid, in animal, 48; varia- tions in plants, 45. Phosphorus, in nutrition, 19; sources of, 18. Physiological studies, knowledge from, 191. Pig, fat, composition of, 359; feeding of, 361; foods for, 3G3, 365; relation of food to growth, 362. Index 449 Plants, relation to animal life, 7, 8, 9; albumin in, 59; distribution ash com- pounds in, 45; living, water in, 33; mineral compounds of, 43 ; propor- tions of elements in, 21. Potash, variations in plants, 45. Pork, production of, 357. Potassium, where found, 19; in nutri- tion, 19. Poultry, effects of food with, 382; feed- ing of, 379; foods for, 379; food needs of, 389; food mixtures for, 396; main- tenance rations for, 393; rations for chicks, 394; rations for laying hens, 393. Practice, conclusions of, 187. Preservation of fodders, influence on digestion, 129. Preparation of foods, influence on diges- tion, 129. Production, relation of food to, 194, 400; unit of, 401. Proteids, 55; composition, 56 ; com- pound, 66; examples of, 57. Protein, classification compounds of, 54; combustion of, 147; definition of, 52; elements in, 30; functions of, 153; how estimated, 53; in fattening ra- tion, 341, 352; in work horse ration, 375; influence on digestion, 137; need of in milk ration, 310 ; production value of, 175; proportion in ration, 291; relation to muscular effort, 167; relative importance of compound, 178; supply of, 262; sources of for milk ration, 313; variations in digestibility of, 122. Ptyalin, 107. Ration, influence of quantity on digest- ibility, 127. Rations, adaptation of, 281; calculation of, 285; compounding of, 280; fat- tening, selection of, 347; for fatten- ing steers. 342. 348; for laying hens, 393; for milk production, 309, 312; cc for poultry, 392; for work horses, 374, 377; for young birds, 394; main- tenance, 295; maintenance for bo- vines, 299; maintenance for horses, 302; maintenance for poultry, 393; manipulation of, 413; palatableness of, 280; proportion of protein, 291; quantity of, 414; relation to quality of product, 292; relation to prices and supply, 293 ; relation to weight of animal, 289; selection of, 280; stand- ards for, 282, 342, 345. Rennin, 113. Respiration apparatus, 196. Rigor mortis, cause of, 61. Roots (and tubers), 224. Roots, productivity of, 261; storage of, Saccharose, 81. Saliva, 106; function of, 107. Salt, in feeding poultry, 391; influence on digestion, 133. Salts, absorption of, 120. Sand, in feeding poultry, 391. Serum albumin, 59. Sheep, composition of, 403; fattening, experiments with, 353 ; fattening, food needs of, 351; fattening, food stand- ards, 352; fattening, growth of, 350; production with, 404, 405 ; selection of ration for, 355. Silage, 212; changes in, 213 ; cutting material for, 221; formation of, 213; maturity crop for, 220. Silo, construction of, 219; changes in, 213; extent of loss from, 215; filling of, 220; nature of loss from, 214; rate of filling, 221. Skim-milk, 254, 255; as food for swine, 363. Slaughter-house refuses, 256. Sodium, in nutrition, 20; sources of, 19. Soil, nitrogen in, 16. Soiling, 263; crops for, 265; succession of crops, 266; systems of, 265. 450 Index Soiling crops, for swine, 366. Sows, feeding of, 360. Species, influence on digestion, 137. Stage of growth, influence on digestion, 130 ; influence on forage crops, 208. Standards, German, 282. Starch, energy of, 175; distribution in seeds, 77 ; productive value of, 176, 177; properties of, 76; residues from manufacture of, 236. Starch (sugar corn) feed, 239. Stai'ch grains, forms of, 76. Starches, the, 75. Steers, composition of, 403 ; composi tion of increase of, 340 ; fattening experiments with, 343, 345; fattening food needs of, 341; fattening, food for 344; production with, 404, 405. Stomach, 108; of horse, 113; of pig, 113 of ruminants, 1087 Storage, influence on digestibility, 135. Straw, energy of, 175; production value of, 177. Straws, the, 223. Sugar, absorption of, 120. Sugar beet molasses, 241. Sugar beet pulp, 240. Sugars, the, 80. Sulfur, in nutrition, 18; sources of, 18. Swine, composition of , 403« production, 404, 405. Teeth, the, 105. Temperature of stable, 415. Trypsin, 117. Urea, elimination of , 149. Valuation feeding stuffs, 268; basis of, 274 ; commercially, 269 ; physiologi- cally, 272; popular standards, 277. Vitellin, 62. Water, 30; amount required by plants, 36; elimination of , 149; hydrogen in, 15 ; in animal, 38 ; in fattening in- crease, 40; in feeding poultry, 389; in feeding stuffs, 36; in hay, 37; in liv- ing plants, 33; oxygen in, 14; varia- tions in feeding stuffs, 37; in plants, 33. Watering, frequency of, 134. Wastes, elimination of, 148. Wheat, offals from, 228. Wheat kernel, 228 ; proportion of parts, 230. Wheat offals, composition of, 231. Whey, 254, 255. The Best and Newest Rural Books BOOKS ON LEADING TOPICS CONNECTED WITH AGRI- CULTURAL AND RURAL LIFE ARE HERE MENTIONED. EACH BOOK IS THE WORK OF A SPECIALIST, UNDER THE EDITORIAL SUPERVISION OF PROFESSOR L. H. BAILEY, OF THE CORNELL UNIVERSITY, OR BY PROFESSOR BAILEY HIMSELF, AND IS READABLE, CLEAR-CUT AND PRACTICAL. THE RURAL SCIENCE SERIES Includes books which state the underlying principles of agriculture in plain language. They are suitable for consultation alike by the amateur or professional tiller of the soil, the scientist or the student, and are freely illustrated and finely made. The following volumes are now ready: THE SOIL. By F. H. King, of the L T niversity of Wisconsin. 303 pp. 45 illustrations. 75 cents. THE FERTILITY OF THE LAND. By I. P. Roberts, of Cornell Univer- sity. 421 pp. 45 illustrations. $1.25. THE SPRAYING OF PLANTS. By E. G. Lodeman, late of Cornell Uni- versity. 399 pp. 92 illustrations. $1.00. MILK AND ITS PRODUCTS. By H. H. Wing, of Cornell University. 311 pp. 43 illustrations. $1.00. THE PRINCIPLES OF FRUIT-GROWING. By L. H. Bailey. 516 pp. 120 illustrations. $1.25. BUSH-FRUITS. By F. W. Card, of Rhode Island College of Agriculture and Mechanic Arts. 537 pp. 113 illustrations. $1.50. FERTILIZERS. By E. B. Voorhees, of New Jersey Experiment Station. 332 pp. $1.00. THE PRINCIPLES OF AGRICULTURE. By L. H. Bailev. 300 pp. 92 illustrations. $1.25. IRRIGATION AND DRAINAGE. By F. H. King, University of Wisconsin. 502 pp. 163 illustrations. $1.50. THE FARMSTEAD. By I. P. Roberts. 350 pp. 138 illustrations. $1.25. RURAL WEALTH AND WELFARE. By George T. Fairchild, Ex-Presi- dent of the Agricultural College of Kansas. 381 pp. 14 charts. $1.25. THE PRINCIPLES OF VEGETABLE-GARDENING. By L. H. Bailey. 468 pp. 144 illustrations. $1.25. THE FEEDING OF ANIMALS. By W. H. Jordan, of New York State Experiment Station. 450 pp. $1.25 net. FARM POULTRY. By George C. Watson, of Pennsylvania State College. 341 pp. $1.25 net. THE FARMER'S BUSINESS HANDBOOK. By I. P. Roberts, of Cornell University. 300 pp. $1.00 net. New volumes will be added from time to time to the Rural Science Series. The following are in preparation : PHYSIOLOGY OF PLANTS. By J. C. Arthur, Purdue University. THE PRINCIPLES OF STOCK BREEDING. By W. H. Brewer, of Yale University. PLANT PATHOLOGY. By B. T. Galloway and associates, of U. S. Depart- ment of Agriculture. CARE OF ANIMALS. By N. S. Mayo, of Connecticut Agricultural College. THE POME FRUITS (Apples, Pears, Quinces). By L. H. Bailey. THE GARDEN-CRAFT SERIES Comprises practical handbooks for the horticultur- ist, explaining and illustrating in detail the various important methods which experience has demon- strated to be the most satisfactory. They may be called manuals of practice, and though all are pre- pared by Professor Bailey, of Cornell University, they include the opinions and methods of success- ful specialists in many lines, thus combining the results of the observations and experiences of nu- merous students in this and other lands. They are written in the clear, strong, concise English and in the entertaining style which characterize the author. The volumes are compact, uniform in style, clearly printed, and illustrated as the subject demands. They are of convenient shape for the pocket, and are substantially bound in flexible green cloth. THE HORTICULTURIST'S RULE BOOK. By L. H. Bailey. 312 pp. 75 cents. THE NURSERY-BOOK. By L. H. Bailey. 365 pp. 152 illustrations. $1. PLANT-BREEDING. By L. H. Bailey. 293 pp. 20 illustrations. $1.00. THE FORCING-BOOK. By L. H. Bailey. 266 pp. 88 illustrations. $1.00. GARDEN-MAKING. By L. H. Bailey. 417 pp. 256 illustrations. $1.00. THE PRUNING-BOOK. By L. H. Bailey. 545 pp. 331 illustrations. $1.50. THE PRACTICAL GARDEN-BOOK. By C. E. HuKN and L. H. Bailky. 250 pp. Many marginal cats. $1.00. T WORKS BY PROFESSOR BAILEY HE SURVIVAL OF THE UNLIKE: A Collection of Evolution Essays Suggested by the Study of Domestic Plants. By L. H. BAILEY, Professor of Horticulture in the Cornell University. FOURTH EDITION — 51 S PACES — 22 ILLUSTRATIONS — $2. 00 To those interested in the underlying philosophy of plant life, this volume, written in a most enter- taining style, and fully illustrated, will prove wel- come. It treats of the modification of plants under cultivation upon the evolution theory, and its atti- tude on this interesting subject is characterized by the author's well-known originality and inde- pendence of thought. Incidentally, there is stated much that will be valuable and suggestive to the working horticulturist, as well as to the man or woman impelled by a love of nature to horticul- tural pursuits. It may well be called, indeed, a philosophy of horticulture, in which all interested may find inspiration and instruction. The Survival of the Unlike comprises thirty essays touching upon The General Fact and Philosophy of Evolution (The Plant Individual, Experimental Evolution, Coxey's Army and the Russian Thistle, Recent Progress, etc.); Expounding the Fact and Causes of Variation (The Supposed Correlations of Quality in Fruits, Natural History of Synonyms, Reflective Impressions, Relation of Seed- bearing to Cultivation, Variation after Birth, Relation between American and Eastern Asian Fruits, Horticultural Geography, Prob- lems of Climate and Plants, American Fruits, Acclimatization, Sex in Fruits, Novelties, Promising Varieties, etc.); and Tracing the Evolution of Particular Types of Plants (the Cultivated Strawberry, Battle of the Plums, Grapes, Progress of the Carnation. Petunia. The Garden Tomato, etc.). T WORKS BY PROFESSOR BAILEY HE EVOLUTION OF OUR NA- TIVE FRUITS. By L. H. BAILEY, Pro* fessor of Horticulture in the Cornell University. 478 PACES -126 ILLUSTRATIONS — 82. 00 In this entertaining volume, the origin and de- velopment of the fruits peculiar to North America are inquired into, and the personality of those horti- cultural pioneers whose almost forgotten labors have given us our most valuable fruits is touched upon. There has been careful research into the history of the various fruits, including inspection of the records of the great European "botanists who have given attention to American economic botany. The conclusions reached, the information presented, and the suggestions as to future developments, can- not but be valuable to any thoughtful fruit-grower, while the terse style of the author is at its best in hi? treatment of the subject. The Evolution of our Native Fruits discusses The Rise of the American Grape (North America a Natural Vineland, Attempts to Cultivate the European Grape, The Experiments of the Dufours, The Branch of Promise, John Adlum and the Catawba, Rise of Commercial Viticulture, Why Did the Early Vine Experiments Fail < Synopsis of the American Grapes) ; The Strange History of the Mul berries (The Early Silk Industry, The "Multicaulis Craze,") ; Evolu- tion of American Plums and Cherries (Native Plums in Genera!, The Chickasaw, Hortulana, Marianna and Beach Plum Groups, Pacific Coast Plum, Various Other Types of Plums, Native Cherries, Dwarf Cherry Group ) ; Native Apples (Indigenous Species, Amelio- ration has begun); Origin of American Raspberry-growing (Early American History, Present Types, Outlying Types) ; Evolution of Blackberry and Dewberry Culture (Tbe High-bush Blackberry and Its Kin, The Dewberries, Botanical Names); Various Types of Berry-like Fruits (The Gooseberry, Native Currants, Juneberry, Buffalo Berry, Elderberry, High-bush Cranberry, Cranberry, Straw- berrv); Various Types of Tree Fruits (Persimmon, Custard-Applo Tribe, Thorn-Apples, Nut-Fruits) ; General Remarks on the Improve- ment of our Native Fruits (What Has Been Done, What Probably Should Be Done). L WORKS BY PROFESSOR BAILEY ESSONS WITH PLANTS: Sugges- tions for Seeing and Interpreting Some of the Common Forms of Vegetation. By L. H. BAILEY, Professor of Horticulture in the Cornell University, with delineations from nature by W. S. HOLDSWORTH, of the Agricultural College of Michigan. SECOND EDITION— 491 PACES— 446 ILLUSTRATIONS— 1 2 MO- CLOTH— SI. 10 NET There are two ways of looking at nature. The old way, which you have found so unsatisfactory, was to classify everything — to consider leaves, roots, and whole plants as formal herbarium specimens, forgetting that each had its own story of growth and development, struggle and success, to tell. Nothing stifles a natural love for plants more effect- ually than that old way. - The new way is to watch the life of every grow- ing thing, to look upon each plant as a living creature, whose life is a story as fascinating as the story of any favorite hero. "Lessons with Plants" is a book of stories, or rather, a book of plays, for we can see each chapter acted out if we take the trouble to look at the actors. " I have spent some time in most delightful examination of it, and the longer I look, the better I like it. I find it not only full of interest, but eminently suggestive. I know of no book which begins to do so much to open the eyes of the student —whether pupil or teacher — to the wealth of meaning contained in simple plant forms. Above all else, it seems to be full of suggestions that help one to learn the language of plants, so they may talk to him."— Darwin L. Bardwell, Superintendent of Schools, Bing- hamton. "It is an admirable book, and cannot fail both to awaken interest in the subject, and to serve as a helpful and reliable guide to young students of plant life. It will, I think, fill an important place in secondary schools, and comes at an opportune time, when helps of this kind are needed and eagerly sought."— Professor V. M. Spalding, University of Michigan. FIRST LESSONS WITH PLANTS An Abridgement of the above. 117 pages — 116 illustra- tions — 40 cents net. WORKS BY PROFESSOR 3AILEY B OTANY : An Elementary Text for Schools. By L. H. BAILEY. 355 PACES— 500 ILLUSTRATIONS— $1 .10 NET "This book is made for the pupil: 'Lessons With Plants' was made to supplement the work of the teacher." This is the opening sentence of the preface, showing that the book is a companion to "Lessons With Plants," which has now become a standard teacher's book. The present book is the handsomest elementary botanical text-book yet made. The illustrations illustrate. They are artistic. The old formal and unnatural Botany is being rapidly outgrown. The book disparages mere laboratory work of the old kind: the pupil is taught to see things as they grow and behave. The pupil who goes through this book will understand the meaning of the plants which he sees day by day. It is a revolt from the dry -as -dust teaching of botany. It cares little for science for science' sake, but its point of view is nature -study in its best sense. The book is divided into four parts, any or all of which may be used in the school: the plant itself; the plant in its environment; histology, or the minute structure of plants; the kinds of plants (with a key, and de- scriptions of 300 common species). The introduction contains advico to teachers. The book is brand new from start to finish. "An exceedingly attractive text-book."— Educational Review. "It is a school book of the modern methods."— The Dial. "It would be hard to find a better manual for schools or for indi- ridual use." — The Outlook. THE MACMILLAN COMPANY No. 66 Fifth Avenue NEW YORK T WORKS BY PROFESSOR BAILEY HE CYCLOPEDIA OF AMERICAN HORTICULTURE : By l. h. bailey, of Cornell University, assisted by WILHELM MILLER, and many expert cultivators and botanists. 4 VOLS.— OVER 2800 ORIGINAL ENGRAVINGS -CLOTH — OCTAVO $20.00 NET PER SET. HALF MOROCCO, $32.00 NET PER SET This great work comprises directions for the cul- tivation of horticultural crops and original descrip- tions of all the species of fruits, vegetables, flowers and ornamental plants known to be in the market in the United States and Canada. "It has the unique distinction of presenting for the first time, in a care- fully arranged and perfectly accessible form, the best knowledge of the best specialists in America upon gardening, fruit-growing, vegetable culture, forestry, and the like, as well as exact botanical information. . . . The contributors are eminent cultivators or specialists, and the arrangement is very systematic, clear and convenient for ready reference." ''We have here a work which every ambitious gardener -will wisli to place on his shelf beside his Nicholson and his Loudon, and for such users of it a too advanced nomenclature would have been confusing to the last degree. With the safe names here given, there is little liability to serious perplexity. There is a growing impatience with much of the controversy concerning revision of names of organisms, whether of plants or animals. Those in- vestigators who are busied with the ecological aspects of organisms, and also those who are chiefly concerned with the application of plants to the arts of agriculture, horticulture, and so on, care for the names of organisms under examination only so far as these aid in recognition and identification. To introduce unnecessary confusion is a serious blunder. Professor Bailey has avoided the risk of confusion. In short, in range, treatment and edit- ing, the Cyclopedia appears to be emphatically useful ; . . . a work worthy of ranking by the side of the Century Dictionary." — The Nation. This work is sold only by subscription, and terms and further information may be had of the publishers. THE MACMILLAN COMPANY No. 66 Fifth Avenue NEW YORK APR 1 11904