UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS AS DETERMINED FOR RUMINANTS PART I. DRIED ORANGE PULP AND RAISIN PULP S. W. MEAD AND H. R. GUILBERT BULLETIN 409 October, 1926 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1926 Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/digestibilityofc409mead THE DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS AS DETERMINED FOR RUMINANTS PART I. DRIED ORANGE PULP AND RAISIN PULP S. W. MEAD* and H. K. GUILBERTt INTRODUCTION Dairy cattlemen in California depend to a large extent upon roughage for feed. Comparative^ speaking, concentrates are little used. Barley which is the grain most commonly fed, is usually high in price. In general, all concentrates are relatively expensive. For this reason, the dairymen are interested in any less expensive product which may be utilized for feeding purposes and especially in feeds which may supplement the roughage used. During the past few years, a number of by-products have become available for replacing some of the more expensive feeds which have been in common use in livestock feeding for many years. In many cases very little is known regarding the nutritive value of these feeds. At times, values not justified by experimental evidence are attributed to certain feeds by the livestock feeder. Requests have come to the University for information concerning the feeding value of many new by-products peculiar to California. Two of these, orange pulp and raisin pulp, have attracted considerable attention. Both are by-products of leading fruit industries in the state, and their economic disposal is of considerable importance. If these by-products have significant feeding values and can be purchased at reasonable prices, the problem of disposal will be solved. Orange pulp is a by-product in the manufacture of orange juice, orange oils, and other orange extracts. During the year ending December 31, 1924, the Exchange Orange Products Company of California, produced more than 9000 tons of the wet or fresh orange pulp. It is estimated that by 1930 the volume of wet pulp to be handled will amount to 50,000 tons. * Assistant Professor of Animal Husbandry, Assistant Animal Husbandman in Experiment Station. t Junior Animal Husbandman in Experiment Station. 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION In a practical way it has been demonstrated that the wet pulp makes a satisfactory feed for dairy cows. Dairymen near the factory are feeding wet pulp, apparently with good results. Raisin pulp is being produced in somewhat smaller quantities than orange pulp. This by-product has also been used for feeding pur- poses, especially in the feeding of beef cattle and sheep, and in some cases, horses. Raisin pulp consists of a mixture of dry battery pulp, dry seeder waste, and stemmer waste. The seeder waste contains some fruit adhering to the stem. The battery pulp is the residue resulting from the extraction of syrup and consists of the raisins after most of the sugar has been extracted. The pulp is thoroughly dried and contains about 8 per cent moisture when leaving the dryer. Digestion and feeding trials with these by-products have been conducted at the University Farm at Davis. The results of the diges- tion trials are reported here, with a description of methods and equipment used. METHODS USED Animals. — It has been definitely shown that the coefficient of digestibility for any given feed is practically the same for all classes of ruminants. Since sheep are small and easily handled they are better adapted to this type of investigation than larger ruminants. For this reason five grade wether sheep of uniform weight and age were used. Digestion stalls and method of collecting feces. — The animals were placed in individual box stalls 4 feet by 8 feet equipped with mangers so constructed as to prevent any possible loss of feed. (See plates 1 and 2.) The feces were collected by means of rubber lined sacks attached to each animal. (See plate 3.) Sample containers. — One quart Golden State Mason jars were used for storing the samples of feeds and feces, and two quart jars were used for the roughage. Length of digestion trial. — The preliminary feeding period was ten days, the collection period fifteen days. Sampling the feed. — The amount of the feed necessary to last throughout the digestion trial was spread out on a clean floor, and was thoroughly mixed and quartered. The individual feeds for the entire period were weighed out into glazed paper bags ; a part of each feed being taken from each of the four piles. The bags were labeled, designating the animals to which the feed contained was to be given. BULL. 409] DIGESTIBILITY OF CERTAIN FRUIT BY-PRODUCTS 5 After every three or four portions had been weighed, a small amount of the feed was taken from each of the four piles to form a composite sample for chemical analysis. The hay was finely cut, then mixed and sampled as above. Feeding manger with front lowered to show construction of manger and stanchion used for fastening animal while eating. Animals were kept in stanchions until all feed had been consumed. Amount fed. — The amounts of the various feeds used were cal- culated to satisfy the maintenance requirements of the animal. All of the feed offered was eaten except a small amount of alfalfa stems which were not cut finely enough in the original cutting. The stems b UNIVERSITY OF CALIFORNIA EXPERIMENT STATION refused were ground in a feed grinder and replaced in the manger of the animal which had originally refused them. In every case this reground feed was consumed by the animal. In this way, there was no refused feed to consider in the final calculations. Feeding manger with front lowered to show animal with head fastened to prevent loss of feed. Handling the feces. — The collection bags were emptied twice daily. The feces were immediately weighed and aliquot portions of the feces of each animal placed in containers which had previously been rinsed in a 10 per cent alcoholic solution of thymol. In addition, powdered Bull. 409] DIGESTIBILITY of certain fruit by-products 7 thymol was sprinkled over the feces after they were transferred from the scales to the jars, to the amount of 5 grams of thymol to each jar. The jars were immediately placed in a refrigerator where they remained until the next time the feces were collected. The refrigerator was maintained at a temperature varying from 28 to 35 degrees Fahrenheit. ^H HP ' **ai W|; mm ^BB( ^(H /^^: .._ JT ta*T^ *m\ % -' . ■lEL^^H ML' \;^P-: : "' fBp' jm Illustrating method used for collecting feces. At the end of the collection period the contents of the several jars representing the total feces collected from each animal were thoroughly mixed, ground, remixed and sampled for chemical analysis. RESULTS OF THE ORANGE PULP AND RAISIN PULP DIGESTION TRIALS The orange pulp and raisin pulp were fed with alfalfa hay, and since the digestibility of the available hay was not known, a digestion determination was made, using the same methods and equipment as those used in the case of the orange pulp and raisin pulp. A sufficient amount of this hay was set aside for the three trials. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION APPARENT DIGESTIBILITY OF DRIED ORANGE PULP The orange pulp used in this trial was dried to approximately 15 per cent moisture and finely ground in order to facilitate handling. The composition of the feeds and feces, total amounts of the feeds consumed by the animals, feces collected, and results of the orange pulp trial are shown in the following tables: TABLE 1 Total Feed Consumed and Total Feces Collected Animal number Alfalfa hay Orange pulp Feces 1 Grams 7800 7800 7800 11550 8775 Grams 3975 3975 3975 5850 4425 Grams 7869 1 2 7948 4 3 7832.9 4 11965 5 5 10049 TABLE 2 Chemical Analyses of Feces and Feeds Feces: Animal Number Dry matter Crude protein Nitrogen-free extract Ether extract Crude fiber 1 Per cent 37.43 37.44 37.60 36.40 33.93 90.78 87.50 Per cent 4.39 4.29 4.28 n 4.17 3,82 15.30 7.70 Per cen t 11.21 11.56 11.55 11.15 10.34 37.86 66.96 Per cent 1.85 1.92 1.83 1.79 1.64 1.81 1.68 Per cent 14.92 2 14.70 3 14.90 4 14.36 5 13.51 Feeds: Alfalfa hay 28.00 Dried orange pulp 7.81 TABLE 3 Coefficients of Digestibility of Alfalfa Hay Used in Digestion Trials with Orange Pulp and Eaisin Pulp Dry matter Crude protein Nitrogen-free extract Ether extract Crude fiber Per cent 63.31±.13 Per cent 77.00±.10 Per cent 73.45±.27 Per cent 20. 31 ±.26 Per cent 48.49±.20 Bull. 409] digestibility of certain fruit by-products TABLE 4 Coefficients of Digestibility of Dried Orange Pulp Animal Number Dry matter Crude protein Nitrogen-free extract Ether extract Crude fiber Per cent Per cent Per cent Per cent Per cent 1 90.0146 76.8222 96.3110 50.4819 84.2074 2 89.1385 78. 2817 94.9318 39.9535 86.0289 3 90.0214 80. 1565 95.4629 53.8307 86. 4517 4 90.0702 79.4711 95.5753 51.5863 88. 5489 5 87. 4283 77.9747 94. 6967 48.5739 73.3941 Average 89. 33 =h. 31 78.54zt.35 95.40d=.17 48.89±1.44 83.73=hl.61 APPARENT DIGESTIBILITY OF RAISIN PULP The composition of the feeds and feces, total amounts of feeds con- sumed by the animals, feces collected, and results of the raisin pulp trial are shown in the following tables : TABLE 5 Total Feed Consumed and Feces Collected Animal Number Alfalfa hay Raisin pulp Feces 1 Grams 7800 7800 7800 11550 8775 Grams 3975 3975 3975 5850 4425 Grams 9137.8 2 8699.4 3 8857.3 4 14111.5 5 10163.0 TABLE 6 Chemical Analyses of Feces and Feeds Feces: Animal Number Dry matter Crude protein Nitrogen-free extract Ether extract Crude fiber 1 Per cent 49.03 52.39 50.25 48.85 50.01 90.58 88.68 Per cent 6.23 6.46 6.33 6.01 6.22 15.46 9.58 Per cent 17.90 19.22 17.87 18.32 18.12 37.72 45.57 Per cent 1.68 1.82 1.67 1.60 1.69 1.80 10.54 Per cent 19.37 2 19.99 3 19.53 4 18.20 5 19.15 Feeds: Alfalfa hay 27.80 Raisin pulp 19.32 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION TABLE 7 Coefficients of Digestibility of Eaisin Pulp Animal Number Dry matter Crude protein Nitrogen-free extract Ether extract Crude fiber Per cent Per cent Per cent Per cent Per cent 1 46.4436 23.3463 52.8195 90.0656 14.9727 2 44.2490 25.2633 50.8128 88.9151 19.0068 3 47.2796 25.6074 57.7383 91.3998 20.2021 4 41.1164 21.9598 46.4074 90. 2531 19. 1076 5 44.8001 24.4921 52.2496 90. 1638 19.4333 Average 44.78±.64 24.13±.40 52.01±1.10 90.16=b.24 18.54±.55 TABLE 8 Digestibile Nutrients Contained in Various Common Feeds Compared with Dried Orange Pulp and Eaisin Pulp Feeding stuff fBarley Dried orange pulp fDried beet pulp fAlfalfa hay, all analyses Raisin pulp Total dry matter in 100 pounds Pounds 90.7 87.5 91.8 91.4 88.7 Digestible nutrients in 100 pounds Crude protein Pounds 9.0 6.0 4.6 10.6 2.3 Carbo- hydrates Pounds 66.8 70.4 65.2 39.0 27.3 Fat Pounds 1.6 0.8 0.8 0.9 9.5 "Total Pounds 79.40 78.31 71.60 51.60 50.98 * Total includes fat times the factor 2.25. t Henry and Morrison, Feeds and Feeding, Table 3, Appendix 1923 Ed. DISCUSSION OF RESULTS The nutritive value of any feed is dependent largely upon the digestibility of its various constituents. This digestibility is calcu- lated by subtracting the amount of a given nutrient in the feces from the amount of the same nutrient in the feed consumed by the animal. This difference, expressed in terms of percentage of the total amount ingested, is called the coefficient of digestibility. This method gives only the apparent digestibility. However, since it is the one that has been used in all previous digestion trials, a fair comparison between the digestibility of the feeds reported here and those reported by other investigators is made possible. According to the figures presented in Table 8, orange pulp com- pares very favorably with barley in total digestible nutrients, though Bull. 409] DIGESTIBILITY of certain fruit by-products 11 somewhat lower in amount of digestible crude protein. Dried beet pulp, which is used in very large quantities by dairymen throughout the country, contains on the average 4.6 per cent digestible crude protein, whereas, the orange pulp used in this trial contained 6.0 per cent. Orange pulp contains 78 per cent total digestible nutrients, while dried beet pulp contains 71.6 per cent total digestible nutrients. In a practical way, however, a difference in feeding value as small as these figures indicate is of no great economic importance. The value of the raisin pulp as shown by these trials was much below that of either barley, dried beet pulp, or dried orange pulp. The raisin pulp contained a larger amount of crude protein than dried orange pulp, but the coefficient of digestibility of the protein in orange pulp was 78.5 while that of the raisin pulp was only 24.1. As shown in tables 4 and 7, 89 per cent of the total dry matter in orange pulp was digested, but only 44 per cent in the raisin pulp. According to the results of the digestion trials herewith reported, dried orange pulp should have a feeding value approximating that of barley, dried beet pulp, and other feeds of a similar nature. Raisin pulp should have a feeding value of approximately two-thirds the value of these feeds. The comparative values of these feeds for beef and milk production will be reported later. ACKNOWLEDGMENT The writers wish to express their appreciation for the assistance given them by Mr. H. W. Allinger, of the Division of Chemistry, in carrying out the analytical work. 10m-10,'2<