"LIBRARY OF THL U N I VERS ITY or ILLINOIS 00.433-444 CIRCULATING CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE H. H. MITCHELL W. E. CARROLL T. S. HAMILTON W. P. GARRIGUS G. E. HUNT UNIVERSITY OF ILLINOIS AGRICULTURAL EXPERIMENT STATION Bulletin 434 CONTENTS PAGE REVIEW OF LITERATURE 16 PLAN OF THE EXPERIMENTS 18 COMPLEX vs. SIMPLE MINERAL MIXTURES (Ex- periment I ) 22 Basal Rations and Supplements 22 Results in Experiment 1 24 COMPARATIVE VALUES OF BONE MEAL, LIMESTONE, AND ROCK PHOSPHATE AS CALCIUM SUPPLE- MENTS (Experiment II) 28 Basal Rations and Supplements 28 Results in Experiment II 28 COMPARATIVE UTILIZATION OF PHOSPHATES AND NORMAL CARBONATE OF CALCIUM (Experiment III) 34 First Test: Food Consumption and Gains 36 Second Test : Metabolism Trials 37 PHOSPHORUS NOT LIKELY TO BE DEFICIENT IN SWINE RATIONS (Experiment IV) 45 Basal Rations and Supplements 46 Results in Experiment IV 46 SUMMARY AND CONCLUSIONS 50 LITERATURE CITED. . General directions for the feeding of mineral supplements to swine and other classes of lire- stock are given in Circular 411, "The Feeding of Mineral Supplements to Livestock," 1933, in n'hich the conclusions of the present study are embodied. 50 , Urbana, Illinois May, 1937 Publications in the Bulletin series report the results of investigations made by or sponsored by the Experiment Station Calcium and Phosphorus Supplements For Growing Swine By H. H. MITCHELL, W. E. CARROLL, T. S. HAMILTON, W. P. GARRIGUS, and G. E. HUNT* MINERALS needed by growing swine, except the sodium and chlorin readily supplied by common salt, are now known by nutrition specialists to be adequately provided by a proper selection of grain feeds and pastures. The requirements and functions of minerals in animal nutrition have been investigated sufficiently for predictions to be made, with a reasonable degree of assurance, as to which minerals will or will not be adequately provided for growing animals by a given combination of feeds. A review of the experimental work upon which this knowledge rests was published by Hamilton 14 * in 1932. Not all practical swine rations, however, are so balanced as to supply all the minerals, besides common salt, needed by growing swine. If plentiful amounts of legume hay or pasture are not available, and if the protein is supplied entirely by vegetable concentrates, calcium is likely to be deficient. Whether, under such conditions, phosphorus also is deficient is a question upon which there is no unanimity of opinion ; but when no protein concentrate is used in the ration, phos- phorus is probably slightly deficient. Under certain conditions and in certain localities other minerals, particularly iron and iodin, may be lacking. But in Illinois iodin may be assumed to be present in sufficient amounts for growing swine unless definite symptoms of goiter or other thyroid disturbances are evident. And for pigs of weaning age or older, iron deficiencies in the ration have never been demonstrated. Furthermore, according to experiments conducted at the Illinois Station, 5 - 6> 7 * neither iron nor iodin added to the rations of growing swine beyond the weaning age may be expected to improve the rate of growth or the health of the animals. In the practical feeding of growing swine, consequently, the problem of supplying the needed amounts of minerals is not compli- H. H. MITCHELL, Chief in Animal Nutrition; W. E. CARROLL, Chief in Swine Hus- bandry; T. S. HAMILTON, Associate in Animal Nutrition; W. P. GARRIGUS, formerly Assistant in Animal Husbandry; and G. E. HUNT, formerly Assistant in Swine Husbandry. The authors acknowledge the assistance of r. I. Nakamura, Assistant in Animal Nutri- tion, who performed all the bone analyses reported in this bulletin. 'These numbers refer to literature citations listed on page 53. 15 16 BULLETIN No. 434 [May, cated. Common salt is, of course, always needed, and beyond that the problem is concerned mainly with calcium and phosphorus require- ments and the utilization of these elements from feeds and minerals in which they are present in relatively abundant amounts. The experi- ments reported in this bulletin were therefore designed mainly to test the availability to growing pigs of the calcium and phosphorus in various mineral supplements commonly used in swine feeding. But the experiments included also an inquiry into the need of swine for minerals other than calcium, phosphorus, and common salt as sup- plements to rations consisting mainly of corn. The impression still prevails in many quarters that the problems of mineral nutrition in practical livestock feeding are numerous and complicated, and that their solutions even now are obscure. This notion persists possibly because of the large number of mineral elements present in animal carcasses and known to be necessary for animal life, but it neglects to consider the fact that all these minerals are present in ordinary farm rations the grains and the forages and that usually most of these elements except the sodium and the chlorin may thus be provided in more than adequate amounts by properly balancing the rations with respect to nonmineral nutrients, especially protein. This state of mind the belief that mineral problems are numerous and complicated is receptive to the proposition that farm animals should be fed mineral supplements generally, if only as a measure of safety; and that, in the absence of specific knowledge to the contrary, the safest course is to use complex mineral mixtures containing even as many as 14 to 16 ingredients. The sale of many commercial mineral mixtures is furthered by fostering this belief. Consequently compari- sons of simple and complex mineral mixtures were included in these studies. REVIEW OF LITERATURE The investigations prior to 1932 on the availability to growing pigs of calcium and phosphorus in various mineral supplements were re- viewed and evaluated by Maynard. 17 * His conclusions are well worth quoting: "The evidence here reviewed suggests that when used under appropriate conditions and free from harmful impurities, various forms of calcium are equal from the standpoint of the chemical composition and strength of the bone formed. Neither soluble nor organic forms appear to have an advantage in this respect. On the other hand the question as to whether they are all equally efficient, as measured by percentage assimilation at minimum levels of intake, cannot be so definitely answered. A great preponderance of the evidence sug- gests an equality in this respect also. However, it is not entirely safe to conclude from the negative evidence reviewed that no differences exist. It is possible 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 17 that many of the experiments may not have been sufficiently critical as regards minimum levels of intake and appropriate calcium-phosphorus ratios. From a physiological point of view this question could well be studied further . . . . " In commenting on this same problem later, Rottensten and May- nard 24 * said that in very few of the comparisons made in preceding studies "could it be said with certainty that the level of intake was sufficiently l*w t bring tut any differente in efficiency which might exist." In conducting experiments concerned with the detection and measurement of differences in the utilization by animals of calcium in minerals or in feeds, it is absolutely necessary to administer the cal- cium at a level incapable (or just capable) of supporting maximum calcium retention. Otherwise, if an excess of calcium is provided, any differences in calcium availability between the sources of the element being compared will be underestimated or may even be entirely obscured. Since the publication of Maynard's review in 1932 only one report on the utilization of calcium supplements by swine has appeared. Ramsbottom 23 * in 1933 reported the results of experiments on growing pigs designed to measure the effect on growth, calcium retention, and bone composition of supplements of calcium carbonate, steamed bone meal, and a commercial preparation of dicalcium phosphate ("Dicapho"), added at different levels to rations which were adequate except for deficiencies in calcium and vitamin D. Quoting from the author's summary "When equivalent amounts of Ca, as present in ground limestone, steamed bonemeal, and Dicapho, were fed at low and high levels of intake to a low-Ca basal ration, the retention of Ca and P by all pigs so fed was similar, with one exception. On a high level of Ca supplementation one pig, which received the limestone supplement, had a less favorable Ca and P retention than the pigs which received the bone meal and Dicapho supplements. When the amount of P in the limestone supplemented ration was increased by the use of a neutral mixture of mono- and di-sodium phosphate to an amount similar to that found in the bonemeal ration, this pig's retention improved. Apparently, hog rations having a Ca:P ratio as wide as 2.13:1 and at the same time supplying minimum quantities of antirachitic are unsatisfactory for best results. Bone analyses were made on the femurs and humeri of one group of 4 pigs. The data collected indi- cate very small differences in the composition of the bones of the pigs which received ground limestone, steamed bonemeal, and Dicapho. The femurs and humeri of a check pig which was fed a low-Ca basal ration, were low in ash, Ca and P content." In the following year, 1934, Rottensten and Maynard 24 * reported the results of a very careful comparison with growing rats, as well as with lactating female rats, of the assimilation of phosphorus in pure dicalcium and tricalcium phosphates, in commercial dicalcium phos- 18 BULLETIN No. 434 [May, phate, and in cooked bone meal. The mineral supplements were added at different levels to a basal ration, which was low both in calcium and in phosphorus and contained no vitamin-D concentrate. At all con- centrations of supplements, the ratio of calcium to phosphorus was kept constant at about 1.5 to 1 by additions of the required amounts of calcium carbonate. The growth experiments were conducted ac- cording to the paired- feeding method or a modification of it involving triplicate feeding. The efficiency of the supplements for the growing rats was measured by the ash content of the bones; for the lactating females it was measured by the weight of the young weaned, the ash content of the femur, and the inorganic phosphorus of the blood. The conclusions from these experiments were, in the words of the authors: "Throughout these three experiments such differences as were shown be- tween the supplements under comparison generally favored a secondary phos- phate over a tertiary product, but we are unwilling to consider this combined evidence as certain proof, because of the small differences involved and the variability of the individual data. It seems very unlikely that any differences which may actually exist are large enough to be of appreciable importance in the selection and use of mineral supplements in practice." This conclusion is a conservative interpretation of the experimental data. The consistent advantage of the secondary phosphates over the tertiary phosphates seems statistically distinct, altho slight in magnitude. PLAN OF THE EXPERIMENTS The experiments reported in this bulletin, carried out with some in- terruptions during the period from the spring of 1929 to the fall of 1933, were concerned in part with an inquiry into the need of swine for minerals other than calcium, phosphorus, and common salt, but mainly with the problem of determining the comparative values of different calcium salts in promoting growth and calcification of the bones when added at low levels to calcium-poor rations. The extent of calcification of the bones was determined (1) by the analysis of selected bones, or (2) by calcium metabolism studies and the estima- tion of total calcium retention. These two methods are equivalent, since over 99 percent of the calcium in the body is located in the skeleton. 4 * The paired- feeding method was used in most of the experiments, so that for any comparison of calcium supplements, or of a mineral supplement and no supplement, the amount of basal ration consumed was the same for the two pigs of each pair. Only under such con- ditions may the differences in growth or calcium retention observed be 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 19 directly and entirely attributed to the differences in supplemental feed- ing. The pigs selected for each pair were of the same breed and sex, were within 4 pounds of each other in weight, and were litter mates whenever such a choice was possible. The pigs were penned in a swine barn and had access to an outside concrete runway. At no time did the pigs have access to vegetation or dirt. They were fed twice daily in individual feeding crates adjacent to the concrete runway. Water was available at all times. Each pair was full-fed in so far as this could be done consistently with the paired- feeding plan. All corn used was yellow: The recorded initial and final weights were the averages of weights taken before feeding on three successive mornings. Individual weights were taken weekly thruout each test. In contrast to many of the experiments relating to calcium metabo- lism reported in the literature on this subject, these experiments were conducted under conditions favoring the maximum utilization of cal- cium. Vitamin D, in particular, was provided to the experimental animals either by the incorporation of 1 percent of cod-liver oil in the basal rations or by assuring adequate solar irradiation. Since the ex- periments were conducted in the spring and summer, direct sunlight was available thruout most of the feeding period. The pens in which the pigs were confined were provided with outside concrete runways and those pigs whose basal ration did not carry cod-liver oil were forced to remain outdoors in the sunlight for at least 30 minutes at midday whenever the sun was shining. Besides promoting better utilization of calcium and phosphorus, vitamin D tends to prevent disturbances of mineral metabolism by variations in the ratio of Ca to P. This relationship between vitamin D, the ratio of Ca to P, and the rate of calcification has not been investigated systemmatically with swine, but it has been studied exhaustively with rats and chickens. In all comparisons of the efficiency of the utilization of food ma- terials with reference to any particular nutrient, the level of intake of that nutrient must be less than that required by the animal for maxi- mum performance (see page 17), and furthermore the level of the nutrient in question must be the limiting factor in the nutritive value of the ration. In these experiments on the utilization of calcium, therefore, it was necessary to arrive at some estimate of the calcium requirements of growing swine. This estimate was made in the fol- lowing manner. From carcass analyses of pigs at different stages of growth it was concluded in an earlier publication from this department 19 * that the 20 BULLETIN No. 434 [May, growing- fattening pig gaining about a pound daily actually uses for maintenance and growth from 2.5 to 3 grams of calcium each day. Assuming a utilization of dietary calcium of 50 percent, 12 * the 2.5 to 3 grams of net calcium are equivalent to 5 to 6 grams of dietary calcium. Other investigators have estimated about the same or slightly higher requirements. Dunlop 8 * compiled in 1935 the results of eight experi- ments from various laboratories in this country and Europe, from which he concluded that for pigs growing from a weight of 30 pounds to a weight of 200 pounds at a rate of 1 to 1.4 pounds daily, the ration should contain at least 45 hundredths of one percent of calcium on the dry-matter basis. This percentage is equal to about 2 grams of dietary calcium per pound of dry matter consumed, or 7 grams of dietary calcium daily for a daily gain of 1 pound and a feed cost of 3.5 pounds of feed per pound of gain. M011gaard 20 * and Axelsson 2 * assessed the calcium requirements of growing pigs at even higher levels, while Spildo 25 * estimated a requirement of 5 grams of calcium daily for a body-weight gain of 500 grams a day, making no allowance for a maintenance requirement of calcium. In the experiments reported herein, the calcium supplements were fed in such amounts as to provide 2 to 5 grams of calcium daily. All the basal rations, mainly yellow corn and soybean oil meal in propor- tions varying with the weights of the pigs, were low in calcium and contained .5 to 1 percent of sodium chlorid and generally 1 or 2 per- cent of cod-liver oil. a In one experiment, in which it was desired to use a basal ration containing no more phosphorus than corn itself, commercial' egg albumin was used as a protein concentrate in place of soybean oil meal. An analysis of these feeds is given in Table 1. The bone meal used as supplement to the basal rations contained 81.42 percent ash and 31.28 percent calcium; the limestone, 38.43 per- cent calcium ; the rock phosphate, 33.40 percent calcium and 3.83 percent fluorin; and the commercial dicalcium phosphate, sold under the name "Dicapho," 88.95 percent ash, 29.56 percent calcium, and 20.40 percent phosphorus. The cod-liver oil used, put out by E. L. Patch and Company of Boston, Mass., for animal feeding, contained a guaranteed high potency in vitamins A and D. CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 21 a I a U. 1 2 O at OB S 2 o i w i o 1 o u o a 1/51000 1^.00 fS 1 E a 2 :28S :ss V O O O <*5 CS i U og 5 O'-taa soooo ^ *^rOO>^* ^^f*5^ . GO 00 00 O ^ ^ fO mt~ tits II ^2322 S3S "~ r " ^^ si fe SS wB 4) S bj 00*3't'PO ^^CSO S2 U 00 Ov bl TSRSSB ^gg 38 Q| -ffiSSS g $8 jra 8 B I : : : : "SITS >>>>' -ff >i>>> C3 7 * Basal Rations and Supplements In this experiment a complex mineral mixture was studied as a supplement to two rations of different types, one containing soybean oil meal as a protein concentrate and the other tankage. To assure adequate amounts of calcium, phosphorus, sodium, and chlorin in the basal rations, .5 to 1 percent of common salt (sodium chlorid) and 1 percent of bone meal were incorporated in each. In a third test, de- signed to measure the effect on growth and bone calcification of a cal- cium supplement (limestone) added to a calcium-deficient diet, the basal ration consisted of yellow corn, soybean oil meal, and salt only. The basal rations used in this experiment are described in Table 2. The complex mixture of mineral salts used in the first two tests was similar to that designed for the synthetic feeding of rats by Osborne and Mendel and modified by Hawk and Oser, 15 * except that in this test with swine the calcium salts were left out, because the purpose of the experiments was to test different calcium supplements. The complex salt mixture used contained the following ingredients: TABLE 2. BASAL RATIONS USED IN THE COMPARISON OF SIMPLE AND COMPLEX MINERAL RATIONS: EXPERIMENT I Tankage rations, for Soybean oil meal rations, Calcium-deficient rations, pigs weighing for pigs weighing for pigs weighing Ingredients Less 100 to Over Less 100 to Over Less 100 to Over than 150 150 than 150 150 than 150 150 100 Ibs. Ibs. Ibs. 100 Ibs. Ibs. Ibs. 100 Ibs. Ibs. Ibs. percl. percl. percl. percl. percl. percl. percl. percl. percl. Ground corn 83.5 87.5 93.5 74 82 90 75 83 91 Tankage 15.0 11.0 5.0 Soybean oil meal 24 16 8 24 16 8 Salt .5 5 5 1 1 1 1 1 1 Bone meal 1 1 1 1 1 1 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 23 Parts Potassium citrate, K S C.H 5 O, H,0 ............................ 88 Potassium sulfate, KiSO 4 .................................... 8.9 Potassium chlorid, KC1 ...................................... 55.7 Potassium phosphate, K 3 PO 4 ................................. 27.0 Sodium phosphate, NaaPCX 12H,O ........................... 81.8 Magnesium phosphate, MgsCPOOi 8H0 ..................... 135.1 Ferric citrate, FeCeHsOi 1.5H,0 ............................. 6.34 Potassium iodid, KI .......................................... 020 Manganese sulfate, MnSO .................................... 079 Sodium fluorid, NaF .......................................... 248 Potassium aluminum sulfate, KAlj(SO4)4 ................. . .. .0245 Two of the three comparisons were made with groups of eight pairs of pigs each, and one with a group of seven pairs. The complex mineral mixture was fed at the rate of 5 grams per head daily to one pig in each pair in the first two comparisons ; and the limestone was fed at the rate of 15 grams per head daily to one pig in each pair in the third comparison. The pigs were started on experiment at weights of 60 to 80 pounds each and carried generally to 175 pounds. TABLE 3. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING THE TANKAGE RATION AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING THE SAME WITH A COMPLEX MINERAL SUPPLEMENT: EXPERIMENT I (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 83.0 29.0 54.0 .514 180 3.34 105 83.9 31.3 52.6 .501 180 3.43 105 60.8 31.7 29.1 .378 116 3.99 77 68.9 34.0 34.9 .453 116 3.31 77 80.3 34.0 46.3 .472 171 3.70 98 82.1 31.7 50.4 .514 171 3.40 98 71.2 29.5 41.7 .350 184 4.40 119 81.6 29.9 51.7 .435 184 3.55 119 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed Pair 5 Pair 6 Pair 7 Control Test Control Test Control Test Final weight 81.2 28.1 53.1 .474 189 3.57 112 76.2 28.6 47.6 .425 189 3.98 112 79.8 30.8 49.0 .500 167 3.41 98 78.0 30.4 47.6 .486 167 3.51 98 78.9 29.9 49.0 .333 208 4.24 147 76.2 29.0 47.2 .321 208 4.40 147 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed 24 BULLETIN No. 434 [May, Results in Experiment I Complex Mixture. The very complete mineral mixture added to basal rations of yellow corn and tankage and yellow corn and soybean oil meal produced in the pigs no better growth or health than did the simple supplement of common salt and steamed bone meal (Tables 3 and 4). The inference may therefore be made from these tests that the basal rations in all probability were not deficient in iodin, iron, manga- nese, or most of the other elements required by animals in small amounts but present in farm feeds. And unless specific evidence to the contrary is obtained, it may also be inferred that practical swine rations are not, as a rule, deficient in these minerals. It is significant that in experiments demonstrating the need of animals for mineral elements present in food materials in very small amounts, such as copper, 10 * manganese, 22 * and zinc, 26 * especially puri- fied rations must be prepared. The content of the element under study must be reduced to a mere trace both by chemical methods and by the judicious selection of food materials from a restricted list. It is true that in certain areas of the earth, forage crops in particular are some- TABLE 4. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING THE SOY- BEAN-OIL-MEAL RATION AND OF THEIR PAI*R MATES, THE TEST PIGS, RECEIVING THE SAME WITH A COMPLEX MINERAL SUPPLEMENT: EXPERIMENT I (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 79.4 38.1 41.3 .393 157 3.81 105 77.1 36.7 40.4 .385 157 3.90 105 79.4 32.7 46.7 .445 169 3.62 105 78.0 32.2 45.8 .436 169 3.69 105 68.9 30.8 38.1 .286 167 4.38 133 60.8 31.7 29.1 .219 167 5.75 133 81.2 31.3 49.9 .475 168 3.37 105 82.5 31.7 50.8 .485 168 3.31 105 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed Pair 5 Pair 6 Pair 7 Pair 8 Control Test Control Test Control Test Control Test Final weight 71.2 29.5 41.7 .298 180 4.30 140 82.1 31.3 50.8 .363 180 3.54 140 68.5 29.9 38.6 .368 131 3.40 105 64.4 29.0 35.4 .337 131 3.71 105 66.2 31.7 34.5 .224 161 4.66 154 49.4 31.7 17.7 .115 161 9.07 154 65.8 29.9 35.9 .395 122 3.39 91 67.1 30.4 36.7 .403 122 3.31 91 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 25 times found to be deficient in these "trace" minerals, notably iodin, 29 * iron, 3 * copper, 21 * and cobalt ; 16 * but exceptional incidents afford no reasonable basis for the presumption that these deficiencies are likely to appear in any particular section of the country. In areas where endemic nutritional disorders have not been noted, the indiscriminate feeding of complex commercial minerals as a measure of insurance against such improbable occurrences would seem to be no less conserva- tive than carrying insurance against property damage by meteorites. Limestone. While the results obtained from the complex mineral- mixture supplement were quite negative in significance, those from limestone added to a calcium-poor basal ration were significantly positive. Six of the eight pigs receiving limestone gained faster than, and one of the others gained as fast as, the control mates (Table 5). The average difference in total gain between pair mates was 3.87 kilograms in favor of the limestone pigs ; the standard deviation of differences was 4.93 kilograms, and the probability that a chance com- bination of uncontrolled factors common to both groups of pigs would produce a mean difference in gain as large as or larger than that ob- TABLE 5. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING A CALCIUM- DEFICIENT RATION AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING THE SAME WITH A LIMESTONE SUPPLEMENT: EXPERIMENT I (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 78.0 32.7 45.3 .458 162 3.57 99 80.3 32.2 48.1 .486 162 3.36 99 76.7 30.4 46.3 .441 172 3.71 105 80.3 28.1 52.2 .497 172 3.29 105 78.9 31.7 47.2 .421 171 3.63 112 79.8 32.2 47.6 .425 171 3.60 112 74.8 34.5 40.3 .407 156 3.86 99 82.5 35.4 47.1 .476 156 3.30 99 Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed Pair 5 Pair 6 Pair 7 PairS Control Test Control Test Control Test Control Test Final weight 79.8 33.6 46.2 .471 157 3.39 98 79.4 32.7 46.7 .477 157 3.36 98 62.1 32.2 29.9 .203 182 6.08 147 78.9 34.0 44.9 .305 182 4.05 147 79.8 30.8 49.0 .333 207 4.22 147 78.5 29.5 49.0 .333 207 4.22 147 78.0 34.5 43.5 .414 166 3.80 105 79.8 36.7 43.1 .410 166 3.84 105 Initial weight Total gain Average daily gain Total feed consumed ... Feed per kgm. gain Days on feed 26 BULLETIN No. 434 [May, fl J 25 ; = O M ^ is o n s u p i'. i ^ IJ H' S ll s| _, o ft IJ u M <2l U 00 GO 00 1 I o S . .1 i I O Percentage con Calcium "2 U 5s 8.3 >- ., o jj boT e < Ibe H c3 I P Si 7 M (Ha 1 u U Fresh weight of bones *< 1. U I! n aO O O O> O O O> O- n of the humeri NP*-MN -- tSNJs-*-,'" "" 9> Ot 9. &> O O ^ O* SSS8SS :** --- M (N -- ts * H " - *"* -N ""* * =88283 :*S SS2^S :SS ^ o. oo oo oo oo oo -woo OC CO CC OC O 1 X WOO t^. O W5 IO 'f IO -O-" IO O> <*i O <*5 -OOfO 29S388 :2S !>_ 06 1*- oo oo oo oo -oooo t^odaooooot^ -odod o> t^ i ts -ooo u -' / -f c 7. "> oo O * 10 *! -rc oo^'C OM -00 ******* '** t>. i^ t> *o oo O f^!^ tfsssssgrss Nugoocio-j :g5; ^ IO ^" IO IO >O 1^ ->CIO veio>oor~vo m ^o 100 is ^ W5 "5 IO IO IO .Tj" t^. O IO O O cOTfr^^T^ rows jas8saa:s= (N tS N N i. 3aH .:<. mill :::::::: a ;;;;;;;; ;: 0< 00 jj "b *b "b o "b 'b o o " b'b'bo'b'bo CSTf lOOt^ 1937} CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 27 served was only .039, according to Student's method 27 ' 28 * of assessing the significance of a mean. This probability is small enough to dis- regard. Hence it may be concluded that the limestone supplement to the calcium-deficient ration promoted more rapid gains in weight of the experimental pigs to which it was administered. Bone Analyses. At the termination of this experiment the pigs were slaughtered, and from each carcass one scapula and one humerus were taken for chemical analysis. The results of the chemical analyses are summarized in Table 6, and a statistical analysis of most of these results is given in Table 7. TABLE 7. STATISTICAL ANALYSIS OF DATA IN TABLE 6 SHOWING DIFFERENCES" BETWEEN PAIR MATES Statistics Fresh weight of bone Water content of bone Ash in dry fat-free bone Calcium content of ash Scapulas Mean gms. +12.9 perct. 4.67 perct. +6.56 perct. + .963 Standard deviation 14.5 5.31 2.82 1.29 Probability 1 " .036 .038 .007 .059 Humeri Mean +18.0 3.51 +5.10 + .654 Standard deviation 11.4 3.53 2.54 .513 Probability 1 * .004 .025 .001 .011 A positive mean difference signifies a greater average measurement for the pigs receiving the limestone supplement over their pair mates receiving none. A negative sign has the contrary meaning. b The probability, on a scale of 1, that chance alone would have produced the mean differences observed or larger ones of the same sign. The calcium supplement (limestone) apparently increased the weight and the ash content, but decreased the water content of the bones. The percentage of calcium in the bone ash was increased, and evidently also the percentage of phosphorus, tho not to the same extent. The mean differences in the phosphorus content of the ash of the individual bones were not significant, but the mean difference computed for the two bones together seems quite significant. This difference was -{- .273 percent, the standard deviation of the fourteen differences was .461 percent, and the probability of a chance outcome only .026. The ratio of calcium to phosphorus in the bone ash was not appreciably disturbed by the limestone supplement. 28 BULLETIN No. 434 [May, COMPARATIVE VALUES OF BONE MEAL, LIMESTONE, AND ROCK PHOSPHATE AS CALCIUM SUPPLEMENTS (EXPERIMENT II) Basal Rations and Supplements Three distinct tests were run in this experiment comparing (1) steamed bone meal and ground limestone; (2) tricalcium phos- phate C.P., and rock phosphate containing 3.8 percent of fluorin; and (3) tricalcium phosphate C.P., and a mixture of the same salt with sufficient calcium fluorid to give the same fluorin content as that possessed by the rock phosphate used in the preceding comparison. The basal ration, the soybean-oil-meal ration described in Table 2 except that 1 percent of cod-liver oil replaced the same amount of bone meal, was the same in all three tests. This basal ration was quite evidently deficient in calcium. The average* basal rations con- sumed contained .05 percent calcium and .32 percent phosphorus. The ratios of calcium to phosphorus in the supplemented rations were as follows: for the limestone supplement, 1.18:1; for the rations in the second test, .81:1 ; and for the rations of the third test, .78:1. The supplements were given daily to the individual pigs in amounts to provide 5 grams of calcium. The pigs, of Poland China or Duroc- Jersey breeds, were started on experiment at weights of 50 to 80 pounds. Only pigs of the same breed and approximately equal initial weights, and, where possible, of the same litter, were paired. Both the pigs in a pair were slaughtered as soon as one pig attained a weight of 175 pounds, except in the case of one pair on the rock phosphate test which was taken off at a lighter weight because of the poor con- dition of the rock-phosphate pig. From each carcass two bones, a scapula and a humerus from the same side, were taken for analysis. Results in Experiment II Rate of Growth. The limestone pigs in five of the eight pairs gained in weight somewhat slower, on an average, than their pair mates getting bone meal (Table 8). This difference, however, was obviously of no statistical significance, and therefore cannot logically be attributed to the difference in composition of the supplements fed. The pig in Pair 6 that received the limestone supplement was definitely pathological towards the end of the experiment, which was terminated for this pair with the death of this pig. On post-mortem examination *The soybean oil meal and corn were fed in different proportions accord- ing to the weight of the pigs. 1937} CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 29 TABLE 8. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING BONE MEAL AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING LIMESTONE, AS THE MINERAL SUPPLEMENTS:" EXPERIMENT II (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 79.8 24.0 55.8 .377 227 4.06 148 80.7 24.5 56.2 .380 227 4.03 148 82.5 25.4 57.1 .405 223 3.90 141 79.4 27.2 52.2 .370 223 4.27 141 80.7 25.9 54.8 .338 230 4.18 162 78.0 27.7 50.3 .310 230 4.56 162 84.4 30.8 53.6 .422 215 4.02 127 78.9 27.7 51.2 .403 215 4.20 127 Total feed consumed Feed per kgm. gain Pair 5 Pair 6 Pair 7 Pair 8 Control Test Control Test Control Test Control Test Final weight 82.1 31.3 50.8 .450 204 4.02 113 81.6 29.9 51.7 .456 204 3.95 113 77.1 30.8 46.3 .389 176 3.80 119 63.5 31.3 32.2 .271 176 5.45 119 80.3 33.6 46.7 .345 189 4.05 134 81.6 33.6 48.0 .358 189 3.94 134 80.3 36.3 44.0 .346 183 4.15 127 78.9 35.8 43.1 .339 183 4.24 127 Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed The basal ration was the soybean-oil-meal ration described in Table 2, except that 1 percent of the bone meal was replaced by cod-liver oil. the pig was found to have a fractured femur and around the fracture a large hematoma. In the second test, in which rock phosphate and pure tricalcium phosphate were compared, one pair of pigs was removed at the end of 35 days of feeding because of the development of pneumonia by the pig receiving the pure phosphate (Table 9). In six of the remaining seven pairs, the rock-phosphate pig gained at a slower rate than its pair mate. The one exception occurred in the pair which reached the final weight in the shortest time. For all pairs on test for as long as 24 weeks, the poorer growth of the rock-phosphate pigs was marked. In the later weeks of the experiment these pigs also appeared definitely less thrifty than their pair mates. It seems quite evident from these records that the rock phosphate was definitely toxic and that the toxic effects were cumulative, since with a constant daily dose, the symptoms (poor appe- tite, swellings on loin, scouring, stiffness, etc.) appeared only in the later stages of the feeding test. In the third test, on the other hand, a mixture of CaF 2 and 30 BULLETIN No. 434 [May, TABLE 9. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING TRICALCIUM PHOSPHATE AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING ROCK PHOSPHATE, AS THE MINERAL SUPPLEMENTS:' EXPERIMENT II (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 27.2 25.9 1.3 .037 24 17.23 35 27.2 24.0 3.2 .091 24 7.39 35 77.6 27.2 50.4 .298 242 4.81 169 71.7 27.2 44.5 .263 242 5.45 169 82.5 27.7 54.8 .326 251 4.58 168 77.6 28.6 49.0 .292 251 5.13 168 84.4 27.7 56.7 .337 225 3.97 168 60.3 27.2 33.1 .197 225 6.80 168 Initial weight Total gain Feed per Icgm. gain PairS Pair 6 Pair 7 Pair 8 Control Test Control Test Control Test Control Test 72.1 27.2 44.9 .266 213 4.75 169 68.0 28.6 39.4 .233 213 5.40 169 79.8 29.5 50.3 .357 215 4.26 141 78.0 30.4 47.6 .338 215 4.50 141 78.9 28.6 50.3 .375 227 4.50 134 81.6 27.7 53.9 .402 227 4.20 134 82.1 29.9 52.2 .370 222 4.25 141 79.4 30.8 48.6 .345 222 4.57 141 Initial weight Total gain Total feed consumed Feed per kgm. gain Days on feed The basal ration was the soybean-oil-meal ration described in Table 2. except that 1 percent of the bone meal was replaced by cod-liver oil. Ca 3 (PO 4 ) 2 containing the same fluorin content as the rock phosphate, exerted no obvious deleterious effects on growing pigs in contrast to the tricalcium phosphate alone, except possibly an impairment of appetite (Table 10). There were no significant differences in total gain between the pair mates of this test. In three pairs the fluorin pig made the greater gain and in five pairs the smaller gain. In all three tests an account was kept of the food refusals, throw- ing light on the appetites of the pigs. The numbers given in Table 11 are the numbers of times that food was left in the feed boxes at the end of an experimental day, necessitating a decrease in the amount of food offered the following day. It is clear that fluorin, ingested either as CaF 2 or as phosphate rock, depressed appetite. It is equally clear also that the fluorin in phosphate rock is more toxic than that in CaF 2 , probably because of the different form in which it occurs. Bone Weights and Analyses. The bones removed from the car- casses of the pigs in this experiment were weighed and analyzed for 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 31 TABLE 10. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING TRI- CALCIUM PHOSPHATE AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING A MIXTURE OF TRICALCIUM PHOSPHATE AND CALCIUM FLUORID, AS THE MINERAL SUPPLEMENTS:' EXPERIMENT II (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test 81.6 27.7 53.9 .382 233 4.32 141 78.9 29.0 49.9 .354 233 4.67 141 78.9 30.4 48.5 .344 215 4.43 141 78.5 30.4 48.1 .341 215 4.47 141 79.4 29.9 49.5 .306 273 5.53 162 86.2 30.4 55.8 .345 273 4.90 162 79.4 31.7 47.7 .356 210 4.42 134 79.4 32.2 47.2 .352 210 4.46 134 Initial weight Average daily gain Total feed consumed Feed per kgm. gain Days on feed PairS Pair 6 Pair 7 Pair 8 Control Test Control Test Control Test Control Test 85.3 31.7 53.6 .317 229 4.29 169 70.8 33.1 37.7 .223 229 6.09 169 79.8 31.7 48.1 .379 210 4.37 127 82.5 32.2 50.3 .396 210 4.18 127 81.6 36.3 45.3 .377 202 4.46 120 82.5 35.8 46.7 .389 202 4.33 120 80.7 36.7 44.0 .297 223 5.08 148 78.9 36.3 42.6 .288 223 5.24 148 Total gain Average daily gain Total feed consumed Feed per kgm. gain The basal ration was the soybean-oil-meal ration described in Table 2, except that 1 percent of the bone meal was replaced by cod-liver oil. moisture, fat, ash, calcium, and phosphorus. Only the results of the ash, calcium, and phosphorus analyses are tabulated here. No effects of the mineral supplements were revealed in the bone weights (Table 12), except in the first test, made with bone meal and limestone; and no effects were observed on the moisture or fat con- tents. In fact, Tests 2 and 3, involving the feeding of fluorin supple- ments, resulted in no differences at all in bone composition between the various series of pair mates. In contrast to the effects on growth TABLE 11. FOOD REFUSALS IN EXPERIMENT II T t 1 Tes L 2 T 13 Bone- meal Lime- stone Ca.(PO4)i Rock phosphate Ca(PC4)t Ca > (POOt + CaFi Number of refusals 21 24 6 49 18 51 32 BULLETIN No. 434 [May, TABLE 12. WEIGHTS OF BONES ANALYZED FROM THE THREE SERIES OF PAIRED PIGS IN EXPERIMENT II (All weights expressed in grams) Pair No. Series 1 Series 2 Series 3 Mineral supplements Mineral supplements Mineral supplements Bone meal Limestone Tri calcium phosphate Rock phosphate Tri calcium phosphate Tri calcium phosphate and calcium fluorid Weights of scapulas 1.. 120 132 128 134 ISO 126 120 134 130 110 109 107 118 164 110 131 112 120 132 132 159 117 105 105 131 126 109 129 98 120 121 116 128 117 135 123 104 124 133 137 136 147 130 123 120 134 127 108 140 138 131 128 2 3 4 5 6 7 8 Average Weights of humeri 1 224 235 219 237 240 205 222 224 226 207 210 190 214 221 200 218 198 207 251 249 249 188 204 200 227 224 201 218 208 202 210 207 222 210 238 212 198 237 227 214 233 237 224 230 225 250 240 219 226 226 229 231 2 3 4 5 6 7 8 Average and appetite, no deleterious effects of fluorin were revealed by any of the analyses made on the bones. On the other hand, the bones produced on the bone-meal supple- ment were quite definitely, tho only slightly, heavier than the bones produced on the limestone supplement. The scapulas of the bone-meal pigs were heavier than those of their pair mates in six of the eight pairs, averaging 130 grams as compared with 120 (Table 12). On statistical analysis, the probability that this was a fortuitous re- sult is only .045. The humeri of the bone-meal pigs also were heavier in all pairs than those of their pair mates, averaging 226 grams as compared with 207 grams. In this case, the probability of a fortui- tous outcome is only .0004. These results thus give high assurance that under conditions of sub-optimal mineral feeding, bone meal will produce heavier bones than will limestone." 'The individual bone weights in this test were published in the Proceedings of the American Society of Animal Production, 1932."* 1937\ CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 33 TABLE 13. COMPOSITION OF BONES OF CONTROL PIGS FED BONE MEAL AND OF THEIR PAIR MATES, THE TEST PIGS, FED LIMESTONE SUPPLEMENT Pair No. and sex Percentage of ash in dry fat-free bone Percentage composition of ash Calcium Phosphorus Control pig Test pig Control pig Test pig Control pig Test pig Composition of scapulas 19 51.52 54.86 52.17 53.28 51.63 54.11 54.16 53.16 53.11 49.21 53.29 50.55 51.96 46.80 50.54 52.06 53.05 50.93 37.18 37.43 36.13 37.72 37.90 37.91 36.16 37.11 37.19 36.52 37.86 36.48 37.24 37.29 37.34 39.92 36.85 37.44 17.97 17.75 18.01 18.12 16.63 17.62 17.90 16.93 17.62 18.50 17.87 19.24 17.65 18.06 18.00 17.42 16.92 17.96 2t? 39 4{f S& 69 79 &tf Average Composition of humeri 1 9 . 56.51 57.13 54.22 56.90 58.12 58.48 56.57 58.25 57.02 55.16 55.89 54.84 55.41 54.21 54.22 54.72 55.35 54.98 37.21 37.16 37.51 36.70 37.92 37.80 37.31 37.60 37.40 37.91 37.28 37.47 37.70 37.78 37.47 35.74 38.03 37.42 17.81 18.28 18.20 18.21 17.92 17.93 19.66 18.05 18.26 18.48 18.91 17.81 18.05 17.86 17. 98 17.97 17.78 18.10 2 49.49 48.82 37.91 36.81 18.14 18.90 89 51.04 51.14 37.97 37.17 18.39 18.70 Average 50.28 51.25 37.41 36.84 18.57 18.56 Composition of humeri ! 51.62 51.47 38 01 36 82 18 79 19 10 89 54.50 54.40 38.41 37.17 19 10 19.35 Average 53.24 54.91 37.68 37.23 18 71 18.71 Not included in the average. phate with reference to the retention in the body of calcium and phos- phorus and also to any possible differential effect of the mineral upon the retention of nitrogen.* The salts used were the best that could be obtained, and were fed daily in amounts to provide 2 grams of calcium for each 1,000 grams of ration consumed. The basal ration, designed to be seriously inadequate in calcium and to contain about as much phosphorus as that in corn, contained 91 percent corn (yellow), 6 per- cent dried egg albumin, 2 percent cod-liver oil, and 1 percent common salt. This ration, presumably adequate in vitamin D, contained an average of 12.94 percent crude protein, .0125 percent calcium, and .255 percent phosphorus. It was fed to the pigs at the rate of 4 pounds per 100 pounds body weight, or as near this rate as the appetites of the pigs would permit. The six metabolism periods of the main test were of 10 days du- "Grateful acknowledgment is made to W. T. Haines, Laboratory Technician in Animal Husbandry, for his assistance in conducting these metabolism trials. The responsibility of the care of the pigs and of the collection, weighing, and sampling of the excreta was his. 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 39 ration each and were preceded by preliminary periods of at least 4 days during which the same amounts of feed and supplement were con- sumed as in the following experimental periods. No feces markers were used. The metabolism periods were so planned as to compare dicalcium phosphate with each of the other supplements in turn. In Periods A and B, the secondary and tertiary phosphates were compared ; in Periods C and D, the secondary phosphate and the carbonate ; and in Periods E and F, the secondary phosphate and the primary phosphate. In the first period of each comparison two of the pigs received one of the mineral supplements and three pigs the other. In the second period the supplemental feeding was reversed. In this way it was hoped to counteract any time-effect on nitrogen, calcium, and phos- phorus metabolism. The pigs were confined in metabolism crates similar in design to those described by Forbes. 11 * At the termination of the principal experiment, consisting of Periods A to F inclusive, an attempt was made to determine the maintenance requirements of the pigs by measuring their output of nitrogen, calcium, and phosphorus while subsisting on a ration very low in these elements. The ration contained 94 percent starch, 1 per- cent yeast, 4 percent salt mixture free of calcium and phosphorus, and 1 percent cod-liver oil. On analysis this ration was found to contain .144 percent nitrogen, .0171 percent calcium, and .0318 percent phos- phorus. After a four- or five-day period of preliminary feeding, col- lections of feces and urine were made for two consecutive periods, G and H, each being three or four days in length. For Pig 4 only one such period, lasting five days, could be secured. During Periods G and H the pigs were fed as much of the ration as they would clean up consistently. Results. The results of the metabolism experiments are presented by periods in Tables 18, 19, and 20, and the data on calcium and phos- phorus retention are summarized in Table 21. The average nitrogen balances and digestion coefficients are summarized in Table 22. The various mineral supplements did not exert any appreciable effect on the digestion or the metabolism of nitrogen (Table 22). None of the differences between the corresponding averages for the second- ary phosphate and the other elements approach statistical significance. In the utilization of calcium and phosphorus, as measured by the amounts retained daily, no significant differences were observed be- tween the secondary phosphate and the other supplements (Table 21). 40 BULLETIN No. 434 [May, TABLE 18. DAILY NITROGEN METABOLISM OF PIGS IN EXPERIMENT IV Pig No. Body weight Calcium supplement Food intake Nitrogen intake Fecal nitrogen Urinary nitrogen Nitrogen balance 1 2 3 kgs. 25.2 46.1 47 Period A Secondary phosphate Secondary phosphate. . . . gms. 900 1 625 1 625 gms. 18.27 32.99 32 99 gms. 3.04 5.73 5 18 gms. 8.95 16.52 16 36 gms. 6.28 10.74 11 45 4 26 9 900 18 27 2.65 8 40 7 22 5 48 2 Tertiary phosphate 1 625 32.99 4.64 17.13 11 22 1 30 3 Period B 1 060 22 37 3.01 11 56 7 80 2 57 Tertiary phosphate 1 950 41.14 5.52 21.67 13 95 3 4 5 1 2 3 58.5 32.8 59.7 35.4 67.1 68 8 Secondary phosphate. . . . Secondary phosphate. . . . Secondary phosphate. . . . Period C Secondary phosphate. . . . Secondary phosphate. . . . Carbonate 1 995 1 135 2 020 1 110 2 100 2 140 42.09 23.95 42.62 22.66 43.26 44.08 6.33 3.11 5.76 2.89 6.84 7.16 21.19 12.03 22.35 12.27 24.40 22.96 14.57 8.81 14.51 7.50 12.02 13 96 4 39 4 1 200 24 72 2 69 13 19 8 84 5 72 Carbonate 2 200 45 32 6 18 25 08 14 06 1 42 7 Period D 1 290 27 09 2 80 14 04 10 25 2 76 7 Carbonate 2 003 41 97 5 48 26 11 10 38 3 4 5 1 2 3 81.5 48.1 82.5 48.9 84.0 89 2 Secondary phosphate. . . . Secondary phosphate. . . . Secondary phosphate. . . . Period E Secondary phosphate. . . . Secondary phosphate. . . . Primary phosphate 2 160 1 440 2 246 1 330 1 831 2 110 45.36 30.24 47.16 26.73 36.80 42 41 6.79 2.76 4.59 2.79 3.94 6.34 23.69 15.58 27.96 16.13 22.62 24 96 14.88 11.90 14.61 7.81 10.24 11 11 4 55.6 Primary phosphate 1 510 30.35 2.96 16 23 11 16 5 89 4 Primary phosphate .... 2 040 41 00 4 54 27 14 9 32 1 55.0 Period F Primary phosphate 500 32 10 3.25 17 59 11 26 2 88 300 27 17 2 64 17 27 7 26 3 4 5 1 99.4 63.1 97.8 54.5 Secondary phosphate .... Secondary phosphate. . . . Secondary phosphate. . . . Period G None 415 730 361 738 29.57 37.02 28.38 1 06 2.58 2.94 2.64 .97 17.56 22.26 17.87 3 63 9.43 11.82 " 7.87 3 54 2 87.6 None 600 .86 .69 6 00 5 83 3 99 9 None 1 000 1 44 54 3 99 3 09 4 64.5 None 860 1 24 76 12 71 12 23 5 96.7 None 400 .58 .25 5 20 4 87 1 54.5 Period H None 600 86 53 3 09 2 76 2 87.6 None 600 86 78 5 00 4 92 3 99 9 None 1 000 1 44 21 3 46 2 23 5 96.7 None 400 58 09 4 28 3 79 Altho in each of the three comparisons the average calcium retention of the pigs on the dicalcium phosphate supplement was the higher, in none of the comparisons did all five pigs show a higher retention for the dicalcium phosphate. In the comparison of the secondary and ter- tiary phosphates in Periods A and B, three of the pigs retained more calcium on the secondary phosphate, but two retained more on the tertiary. In the comparison of secondary phosphate and carbonate, the division was again 3 to 2 in favor of the former, while for secondary and primary phosphates it was 3 to 2 in favor of the latter. 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 41 TABLE 19. DAILY CALCIUM METABOLISM OF PIGS IN EXPERIMENT IV Pig No. Calcium supplement Calcium intake Fecal calcium Urinary calcium Calcium balance Feed Suppl. Total Total Percent of intake 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 5 Period A gms. .16 .28 .28 .16 .28 .12 .23 .23 .13 .24 .12 .24 .25 .14 .25 .17 .03 .29 .19 .25 .15 .21 .24 .17 .23 .18 .13 .14 .21 .09 .13 .10 .17 .15 .07 .10 .10 .17 .07 gms. 1.80 3.25 3.25 1.80 3.25 2.12 3.90 3.99 2.27 4.04 2.22 4.20 4.28 2.40 4.40 2.58 4.20 4.32 2.88 4.52 2.66 3.96 4.22 3.02 4.28 3.00 2.60 2.83 3.46 2.85 gms. 1.96 3.53 3.53 1.96 3.53 2.24 4.13 4.22 2.40 4.28 2.34 4.44 4.53 2.54 4.65 2.75 4.23 4.61 3.07 4.77 2.81 4.17 4.46 3.19 4.51 3.18 2.73 2.97 3.67 2.94 .13 .10 .17 .15 .07 .10 .10 .17 .07 gms. .87 1.79 1.61 .97 1.73 .80 1.91 1.78 1.11 1.98 .70 1.87 1.67 .92 1.79 .77 1.56 1.47 .85 2.44 .64 1.62 1.68 1.11 2.09 .83 1.31 .83 .88 1.15 .36 .30 .17 .18 .17 .16 .40 .04 .03 gms. .05 .12 .09 .04 .16 .05 .07 .11 .04 .10 .03 .10 .15 .19 .29 .59 .13 .08 .04 .11 .04 .07 .15 .05 .17 .06 .04 .05 .05 .04 .041 .058 .043 .045 .028 .042 .060 .073 .031 gms. 1.04 1.62 1.83 .95 1.64 1.39 2.15 2.33 1.25 2.20 1.61 2.47 2.71 1.43 2.57 1.39 2.54 3.06 2.18 2.22 2.13 2.48 2.63 2.03 2.25 2.29 1.38 2.09 2.74 1.75 -.27 -.26 -.05 -.08 -.13 -.10 -.36 + .06 -.01 53.1 45.9 51.8 48.5 46.5 62.1 52.1 55.2 52.1 51.4 68.8 55.6 59.8 56.3 55.3 50.5 60.0 66.4 71.0 46.5 75.8 59.5 59.0 63.6 49.9 72.0 50.5 70.4 74.7 59.5 Secondary phosphate Tertiary phosphate Period B Tertiary phosphate Secondary phosphate Period C Secondary phosphate Carbonate Carbonate Period D Carbonate Secondary phosphate Period E Secondary phosphate Primary phosphate Primary phosphate Period F Primary phosphate Secondary phosphate Secondary phosphate Period G None None None None Period H None None None On the basis of the percentage of calcium intake that was retained, the verdicts of the individual pigs were 3 to 2 in favor of the second- ary over the tertiary phosphate, 3 to 2 in favor of the secondary phos- phate over the carbonate, and 5 to in favor of the secondary over the primary phosphate. Only the last result is statistically significant, the mean difference between the two results on each of the five pigs being -|- 8.8 percent, the standard deviation of differences, 3.2, and 42 BULLETIN No. 434 [May, TABLE 20. DAILY PHOSPHORUS METABOLISM OF PIGS IN EXPERIMENT IV Pig No. Calcium supplement Phosphorus intake Fecal phos- phorus Urinary phos- phorus Phosphorus balance Feed Suppl. Total Total Percent of intake 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 5 Period A Secondary phosphate gms. 2.31 4.18 4.18 2.31 4.18 2.85 5.25 5.37 3.05 5.43 2.78 5.31 5.41 3.04 5.57 3.35 5.19 5.62 3.74 5.83 3.25 4.47 5.15 3.68 4.98 3.84 3.20 3.48 4.43 3.33 .23 .19 .32 .27 .13 .19 .19 .32 .13 gms. 1.29 2.33 1.80 .99 1.80 1.17 2.16 2.87 1.63 2.90 1.72 3.25 3.34 2.23 3.49 2.05 3.06 6.97 4.99 7.07 4.96 4.30 2.19 2.67 2.20 gms. 3.60 6.51 5.98 3.30 5.98 4.02 7.41 8.24 4.68 8.33 4.50 8.56 5.41 3.04 5.57 3.35 5.19 8.96 5.97 9.32 5.30 7.53 12.12 8.67 12.05 8.80 7.50 5.67 7.10 5.53 .23 .19 .32 .27 .13 .19 .19 .32 .13 gms. 1.73 3.36 2.85 1.69 3.17 1.88 3.85 3.58 2.16 3.72 2.08 4.20 3.79 1.97 3.64 1.99 3.40 3.95 2.19 4.05 2.16 3.13 5.38 2.72 4.28 2.80 2.27 2.12 2.53 2.12 .82 .42 .29 .46 .20 .38 .57 .06 .06 gms. .97 1.37 1.18 .62 1.24 .77 1.49 2.18 1.19 2.30 1.41 2.65 .06 .04 .08 .05 .19 2.65 1.65 2.74 1.61 2.19 5.40 3.61 5.09 3.89 3.54 1.95 2.20 1.95 .512 .552 .439 .599 .552 .199 .366 .215 .458 gms. .90 1.78 1.95 .99 1.57 1.37 2.07 2.48 1.33 2.31 1.01 1.71 1.56 1.03 1.85 1.31 1.60 2.36 2.13 2.53 1.53 2.21 1.34 2.34 2.68 2.11 1.69 1.60 2.37 1.46 -1.10 - .78 - .41 - .79 - .62 - .39 - .75 + .05 - .39 25.0 27.3 32.6 30.0 26.3 34.1 27.9 30.1 28.4 27.7 22.4 20.0 28.8 33.9 33.2 39.1 30.8 26.3 35.7 27.1 28.9 29.3 11.1 27.0 22.2 24.0 22.5 28.2 33.4 26.4 Tertiary phosphate Period B Tertiary phosphate Tertiary phosphate Secondary phosphate Secondary phosphate Period C Secondary phosphate Secondary phosphate Carbonate Period D Carbonate Secondary phosphate Secondary phosphate .... Secondary phosphate Period E Secondary phosphate Secondary phosphate .... Primary phosphate Primary phosphate Primary phosphate Period F Primary phosphate Primary phosphate Secondary phosphate . . . Secondary phosphate Secondary phosphate Period G None None None None Period H None None None None the probability of a fortuitous outcome only .0028. Therefore, meas- ured by the percentage of the calcium intake retained, the secondary phosphate, altho markedly less soluble than the primary phosphate, was better utilized in the metabolism of the growing animal. Altho the experiment was not designed to obtain valid comparisons of the utilization of phosphorus in the various supplements or supple- mented rations, the same kind of calculations that were made from the 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 43 TABLE 21. SUMMARY OF UTILIZATION OF CALCIUM AND PHOSPHORUS IN THE DIFFERENT RATIONS AND SUPPLEMENTS Calcium balance Phosphorus balance Pi ir Body Food Ca P Period weight, intake. intake. intake, kilograms grams grams grams Percent Percent Grams of Grams of intake intake Secondary phosphate 1 2 3 4 5 Avei A... 25 46 58 33 60 44.4 900 1 625 1 995 1 135 2 020 1.96 3.53 4.22 2.40 4.28 3.28 3.60 6.51 8.24 4.68 8.33 6.27 1.04 1.62 2.33 1.25 2.20 1.69 53 46 55 52 51 51.4 .90 1.78 2.48 1.33 2.31 1.76 25 27 30 28 28 27.6 A B B B age Tertiary phosphate 1 2 3 4 5 Avei B... 30 57 47 27 48 41.8 1 060 1 950 1 625 900 1 625 2.24 4.13 3.53 1.96 3.53 3.08 4.02 7.41 5.98 3.30 5.98 5.34 1.39 2.15 1.83 .95 1.64 1.59 62 52 52 48 46 52.0 1.37 2.07 1.95 .99 1.57 1.59 34 28 33 30 26 30.2 B A A A age Secondary phosphate 1 2 3 4 5 Avei C... 35 67 81 48 82 62.6 1 110 2 100 2 160 1 440 2 246 2.34 4.44 4.61 3.07 4.77 3.85 4.50 8.56 8.96 5.97 9.32 7.46 1.61 2.47 3.06 2.18 2.22 2.31 69 56 66 71 46 61.6 1,01 1.71 2.36 2.13 2.53 1.94 22 20 26 36 27 26.2 c D D D Carbonate 1 2 3 4 5 Avei D 43 77 69 39 72 60.0 1 290 2 003 2 140 1 200 2 200 2.75 4.23 4.53 2.54 4.65 3.74 3.35 5.19 5.41 3.04 5.57 4.51 1.39 2.54 2.71 1.43 2.57 2.13 50 60 60 56 55 56.2 1.31 1.60 1.56 1.03 1.85 1.47 39 31 29 34 33 33.2 D C C C age Secondary phosphate 1 2 3 4 5 Avei E... 49 84 99 63 98 78.6 1 330 1 831 1 415 1 730 1 361 2.81 4.17 2.97 3.67 2.94 3.31 5.30 7.53 5.67 7.10 5.53 6.23 2.13 2.48 2.09 2.74 1.75 2.24 76 59 70 75 59 67.8 1.53 2.21 1.60 2.37 1.46 1.83 29 29 28 33 26 29.0 E F F F age Primary phosphate 1 F... 55 1 500 3.18 8.80 2.29 72 2.11 24 2 F 88 1 300 2.73 7.50 1.38 50 1.69 22 3 E 89 2 110 4.46 12.12 2.63 59 1.34 11 4 E 56 1 510 3.19 8.67 2.03 64 2.34 27 5 E 89 2 040 4.51 12.05 2.25 50 2.68 22 Avei age 75.4 3.61 9.83 2.12 59.0 2.03 21.2 44 BULLETIN No. 434 [May, TABLE 22. AVERAGE NITROGEN BALANCES AND DIGESTION COEFFICIENTS Calcium salt Periods Average daily N balance Average digestibility of N Secondary phosphate A and B gms. 10.98 perct. 84.9 Tertiary phosphate A and B 10.33 85.8 Secondary phosphate C and D 12.18 87.5 Carbonate C and D 11.50 87.2 Secondary phosphate E and F 9.43 90.6 Primary phosphate E and F 10.02 88.9 results of the calcium study have also been made from the results of the phosphorus study. Certain conditions in the phosphorus study tended to invalidate the data. These were (1) the wide variations in phosphorus intake depending upon the chemical constitution of the various supplements, and (2) the fact that a very considerable frac- tion of the phosphorus intake was derived from the basal ration. No clear-cut differences between the utilization of the phosphorus in the rations supplemented with dicalcium-phosphate and in those supplemented with the other minerals were evident in the phosphorus balances in Table 21 altho, as with the calcium, some slight advantage not statistically significant rested with the dicalcium phosphate. On the basis of percentage retention of phosphate, the tertiary phosphate and the carbonate were higher than the secondary phosphate, but the secondary phosphate was higher than the primary phosphate. The results of the low-calcium and low-phosphorus feeding Periods G and H, in which it was hoped to get some measure of the daily output of calcium and phosphorus on a ration extremely poor in these elements, were so variable as to possess little definite significance, except possibly when averaged together. In all probability, less vari- able results would have been secured if feces markers had been used, altho the purpose of feces markers is only partly served when the nutrients to be traced are excreted into the intestinal lumen from the blood. The average loss of calcium per kilogram of body weight for all 5 pigs and for both periods was only 1.6 milligrams. The average loss of phosphorus on the same basis was 7 milligrams. These small losses may approximate the minimum maintenance requirements of swine for calcium and phosphorus, altho much larger figures for these requirements are sometimes quoted in the literature on the subject. The greater loss of phosphorus than of calcium should not be surpris- ing in view of the more active role that phosphorus assumes in animal metabolism. 1937] CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 45 In discussing the calcium requirement for maintenance and the remarks apply equally well to phosphorus Ellis and Mitchell 9 * con- cluded that, in growing animals at least, there may be no integral re- quirement at all: "In the adult, the maintenance requirement for calcium may well represent merely a leakage of calcium ions through the kidney and the walls of the in- testinal tract, due entirely to physico-chemical processes. Calcium ions liberated in the course of catabolism from functional combinations in the tissues and body fluids are probably just as available for the reconstruction of such com- binations as are calcium ions picked up from the intestinal tract. In the young growing animal these 'used' ions as well as the calcium ions coming directly from the alimentary tract may be absorbed and retained by the developing bones and the growing tissues at such a rapid rate that, at low levels of calcium feeding, the threshold of excretion by the kidneys and the intestines is never reached." (EXPERIMENT IV) Whether the rations usually fed to swine are ever likely to be deficient in phosphorus is an extremely practical question. The most readily available minerals that carry both phosphorus and calcium are either relatively expensive, as are various bone preparations and di- calcium phosphate, or, as the rock phosphates, are toxic when used in- discriminately, especially in the self-feeder. On the other hand, the various forms of calcium carbonate, such as limestone, wood ashes, marl, oyster and mussel shells, and marble dust, are cheap, readily available, and innocuous. In the experiment described in the foregoing section a supplement of pure calcium carbonate added to a calcium-deficient diet induced in growing pigs retentions of calcium not to be distinguished in mag- nitude from the retentions induced by dicalcium phosphate. This result might be taken to indicate that the basal diet, consisting largely of corn, was not deficient in phosphorus. However, in an earlier ex- periment with practically the same basal diet, a bone-meal supplement produced a somewhat larger and better calcified bone than a supple- ment of limestone containing an equal amount of calcium (Tables 11 and 15). These results are somewhat difficult to reconcile. It may be that the calcium of bone meal is utilized only slightly better by the growing animal so slightly that a long-continued feeding period is required to demonstrate the difference. Or it may be that the basal ration was only slightly deficient in phosphorus. It is possible also that the calcium of pure calcium carbonate is utilized better than that 46 BULLETIN No. 434 [May, of limestone. To throw some light upon this question the paired- feeding experiment described below was carried out. Basal Rations and Supplements Six pairs of Chester White pigs, one pair of Hampshire pigs, and one pair of Duroc- Jersey pigs were selected at initial weights ranging from 60 to 70 pounds. All were fed a ration composed mainly of corn, fairly well balanced, and containing no more phosphorus than corn itself. It was composed of 92.5 percent corn (yellow), 5 percent soy- bean oil meal, .5 percent cod-liver oil, 1.5 percent marble dust, and .5 percent salt. This ration contained only 11.58 percent protein (un- doubtedly deficient for maximum growth), .754 percent calcium, and .340 percent phosphorus. The phosphorus content was but little higher than that cited by Henry and Morrison for the average phosphorus content of corn, .302 percent. The pigs were housed in the swine barn and had access to an adjacent concrete runway outdoors. Thruout the feeding period of 16 to 24 weeks one pig in each pair received daily a supplement of sodium phosphate (Na 3 PO 4 ) contain- ing 1 gram of phosphorus. Otherwise the pair mates received the same kind and amount of feed and the same treatment. Water was available at all times. Body weights were taken weekly, while both the initial and the final weights were averages of weights for three consecutive days. The experiment on each pair was terminated, except for two pairs, when one pair mate attained a weight of approximately 175 pounds. Two pairs grew so slowly that this weight was not attained in 24 weeks. At the termination of the feeding period all the pigs were slaughtered, and two bones, a scapula and a humerus, were taken from each pig for chemical analysis in order to determine the effect of the phosphate supplement on calcium and phosphorus retention. The experiment started May 26, 1933. During the month of August the appetites of the pigs were so poor and the gains so slow that from August 28 to September 8, a period of 10 days, all pigs were given a daily supplement of 4 pounds of skim milk. This departure from the plan of the experiment could have no serious effect upon the re- sults, since the phosphorus content of the total ration consumed was raised thereby only from .340 to .349 percent. Results in Experiment IV Rate of Growth. The growth of the pigs was evidently not ac- celerated by the phosphorus supplement, since in four pairs the con- trol pig receiving no additional phosphorus gained faster than his pair 1937} CALCIUM AND PHOSPHORUS SUPPLEMENTS FOR GROWING SWINE 47 mate (Table 23). One test pig that did not attain a weight of 100 pounds in 24 weeks was obviously pathological. The average daily gains, excluding this pig and his pair mate, were .75 pound for the control pigs and .78 pound for the test pigs. In spite of these slow gains, which, however, do not invalidate the comparison in the slightest, the feed cost of gains was not excessive. For the control pigs 414 pounds and for the test pigs 398 pounds of feed were required to TABLE 23. GAINS AND FEED CONSUMPTION OF CONTROL PIGS RECEIVING No MINERAL SUPPLEMENT AND OF THEIR PAIR MATES, THE TEST PIGS, RECEIVING A SODIUM PHOSPHATE SUPPLEMENT TO A BASAL DIET CONTAINING ADEQUATE CALCIUM:" EXPERIMENT IV (All weights expressed in kilograms) Pair 1 Pair 2 Pair 3 Pair 4 Control Test Control Test Control Test Control Test Final weight 65.6 34.4 31.2 .19 152 4.87 168 44.8 30.3 14.5 .09 152 10.48 168 69.2 29.9 39.3 .23 179 4.55 168 62.9 29.4 33.5 .20 179 5.34 168 75.6 30.3 45.3 .38 179 3.95 119 81.0 33.0 48.0 .40 179 3.73 119 79.7 32.1 47.6 .43 172 3.61 112 78.7 31.2 47.5 .42 172 3.62 112 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed PairS Pair 6 Pair 7 PairS Control Test Control Test Control Test Control Test Final weight 72.0 30.8 41.2 .31 186 4.51 133 81.0 32.1 48.9 .37 186 3.80 133 78.3 29.0 49.3 .35 199 4.04 140 78.7 29.4 49.3 .35 199 4.04 140 65.6 27.2 38.4 .24 187 4.87 161 80.1 29.0 51.1 .32 187 3.66 161 79.2 30.3 48.9 .44 171 3.50 112 77.8 31.2 46.6 .42 171 3.67 112 Initial weight Total gain Average daily gain Total feed consumed Feed per kgm. gain Days on feed The basal ration consisted of 92.5 percent yellow corn, 5 percent soybean oil meal, .5 percent cod-liver oil, 1.5 percent marble dust, and .5 percent salt. produce 100 pounds of gain. No difference in the appetites of test and of control pigs, as measured by the food refusals, was noted. The data on weights of fresh bones did not reveal any statistically adequate evidence of an effect of the phosphate supplement, and con- sequently are not tabulated here. Of the sixteen bone comparisons, only ten favored the supplement. The average weights of scapulas were 106 and 109 grams for the basal and the supplemented ration respectively, while the average weights of humeri were 217 and 219 grams, in the same order. 48 BULLETIN No. 434 [May, Bone Analyses. The bone analyses also revealed no advantages from the phosphorus supplement (Table 24). Of the sixteen com- parisons between the phosphate-supplement pigs and the control pigs for the calcification of the two bones analyzed, eight favored the con- trol pigs and eight the test pigs. The degree of calcification of the bones is measured by the percentage of total ash on the dry fat- free basis. The average percentages of ash for the control and for the test TABLE 24. COMPOSITION OF BONES OF CONTROL PIGS FED No SUPPLEMENT AND OF THEIR PAIR MATES, THE TEST PIGS, FED A SUPPLEMENT OF SODIUM PHOSPHATE Pair No. and sex Percentage of ash in dry fat-free bone Percentage composition of ash Calcium Phosphorus Control pig Test pig Control pig Test pig Control pig Test pig Composition of scapulas 1