THE UNIVERSITY OF ILLINOIS LIBRARY O AGRICULTURAL IJBRARV UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 200 WITH SPECIAL REFERENCE By H. S. GRINDLEY, W. J. CARMICHAEL, AND C. I. NEWLIN URBANA, ILLINOIS, MAY, 1917 CONTENTS OF BULLETIN No. 200 Page 1. OBJECTS OF EXPERIMENTS 55 FIRST SERIES OF EXPERIMENTS, 1913-1914 2. PLAN 55 3. CHEMICAL COMPOSITION OF FEEDS AND FECES; AND WEIGHTS OF PIGS, FEEDS, WATER, FECES, AND URINE , 56 4. COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS OF THE RATIONS (a) Wheat flour middlings 61 (b) Ground corn 62 (c) Wheat flour middlings and ground corn (1 to 1) 62 (d) Tankage and ground corn (1 to 7.5) 63 5. THE INFLUENCE OF ONE FEED UPON THE DIGESTIBILITY OF THE NUTRIENTS OF ANOTHER FEED 65 6. COEFFICIENTS OF DIGESTIBILITY OF MIDDLINGS, DIRECTLY AND INDIRECTLY DETERMINED 67 7. COEFFICIENTS OF DIGESTIBILITY OF GROUND CORN, DIRECTLY AND INDI- RECTLY DETERMINED 68 8. COEFFICIENTS OF DIGESTIBILITY OF A RATION OF MIDDLINGS AND GROUND CORN (1 TO 1), DIRECTLY AND INDIRECTLY DETERMINED 69 9. INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGEST THEIR FEED 70 10. SUMMARY OF THE COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS SHOWING THE INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGESTED THEIR FEED IN THE FIRST SERIES OF EXPERI- MENTS 72 SECOND SERIES OF EXPERIMENTS, 1914-1915 11. PLAN 72 12. CHEMICAL COMPOSITION OF FEEDS AND FECES; AND WEIGHTS OF PIGS, FEEDS, WATER, FECES, AND URINE 73 13. COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS OF THE RATIONS (a) Ground barley 75 (b) Ground corn 77 (c ) Ground barley and ground corn (1 to 1) 77 (d) Tankage and ground com (1 to 7.5) 80 14. THE INFLUENCE OF ONE FEED UPON THE DIGESTIBILITY OF THE NUTRIENTS OF ANOTHER FEED 80 15. COEFFICIENTS OF DIGESTIBILITY OF GROUND BARLEY, DIRECTLY AND INDI- RECTLY DETERMINED 81 16. COEFFICIENTS OF DIGESTIBILITY OF GROUND CORN, DIRECTLY AND INDI- RECTLY DETERMINED 82 17. COEFFICIENTS OF DIGESTIBILITY OF A RATION OF GROUND BARLEY AND GROUND CORN (1 TO 1), DIRECTLY AND INDIRECTLY DETERMINED. ... 83 18. INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGEST THEIR FEED 85 19. SUMMARY OF THE COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS SHOWING THE INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGESTED THEIR FEED IN THE SECOND SERIES OF EX- PERIMENTS.. 87 20. SUMMARY OF DATA OF BOTH SERIES OF EXPERIMENTS 87 21. CONCLUSIONS.. 89 DIGESTION EXPERIMENTS WITH PIGS WITH SPECIAL REFERENCE TO THE INFLUENCE OF ONE FEED UPON ANOTHER, AND TO THE INDIVIDUALITY OF PIGS BY H. S. GRINDLEY, CHIEF IN ANIMAL NUTRITION, W. J. CARMICHAEL, FIRST ASSISTANT IN ANIMAL HUSBANDRY, AND C. I. NEWLIN, FIRST ASSISTANT IN ANIMAL HUSBANDRY OBJECTS OF THE EXPERIMENTS The objects of the experiments reported in this bulletin were as follows: (a) to determine the influence of one feed upon the digesti- bility of the nutrients of another feed; (b) to study the individual- ity of pigs as to the thoroness with which they digest their feed ; and (c) to determine the coefficients of apparent digestibility 1 of the nutri- ents of the following rations: (1) wheat flour middlings, (2) ground corn, (3) ground barley, (4) wheat flour middlings and ground corn in the ratio of 1 to 1, (5) ground barley and ground corn in the ratio of 1 to 1, and (6) tankage and ground corn in the ratio of 1 to 7.5. In order to secure experimental data that would answer the questions suggested by the above objects, ground corn, wheat flour middlings, and tankage were the feeds used in the first series of ex- periments; and ground corn, ground barley, and tankage were used in the second series of experiments. FIRST SERIES OF EXPERIMENTS, 1913-1914 PLAN Four cross-bred Berkshire-Chester White barrows a little over seven months old, and all from the same litter, were selected for this work and put into specially constructed pens. These pens (Fig. 1) were large enough to allow the pigs to turn around conveniently, and were raised some three feet from the floor to enable an easy collection of the urine. They were provided with removable galvanized-iron feed troughs (Fig. 2) 'and with hinged doors, thru which the animals were 1 Strietly speaking, the coefficients of the real digestibility of the nutrients of feeds cannot as yet be determined, for it is impossible to estimate accurately in the feces, either the metabolic products of intestinal action or the products resulting from tissue metabolism that are excreted thru the intestinal walls into the alimen- tary canal. Therefore, thruout this bulletin the coefficients of digestibility represent the coefficients of apparent digestibility; that is, merely the differences between the weights of the nutrients in the feeds and in the feces expressed in percent of the former. 55 56 BULLETIN No. 200 [May, driven to the weighing crate. The floor, consisting of a strong wire screen, fitted tightly over a galvanized-iron hopper leading to the urine pail (Fig. 3). No chemical analyses of the urines were made. The f eces, collected in rubber-lined canvas bags held in place by means of a specially constructed harness (Fig. 4), were removed each day and placed in friction-top cans. Corn and wheat flour middlings were chosen because they are two of the most common and practical feeds used for swine in the corn belt. No. 2 yellow corn was used. Digester tankage (meat meal) con- taining over 60 percent of protein was fed in two periods of the ex- periment. The barrows were fed twice daily, at 7 a. m. and 5 p. m. The different rations were given in amounts that the pigs would clean up readily, this quantity being determined during a period of several days' duration immediately preceding the experiments proper. Each of the rations was mixed with a definite amount of water (as much as the pigs would take) and fed as a moderately thin slop. The first ration for which the coefficients of digestibility were de- termined consisted approximately of 2.17 pounds of middlings per 100 pounds live weight; the second, of 1.04 pounds of middlings and 1.04 pounds of ground corn per 100 pounds live weight; the third, of 2.06 pounds of ground corn per 100 pounds live weight ; the fourth of 1.84 pounds of middlings per 100 pounds live weight; and the fifth, of 1.74 pounds of ground corn and 0.23 pounds of tankage per 100 pounds live weight. Each of these rations was fed for two ten- day test periods, during which time composite samples of the feeds and feces were taken for chemical analysis. Each group of the two ten-day test periods was preceded by a pre- liminary period of twenty-five to thirty-two days' duration. During the first seven to ten days of each preliminary period, the change in the kinds of feed was made ; during the remainder of the preliminary period, the pigs were fed the same ration in the same amounts per hundred pounds of live weight that they were to be fed during the two test periods immediately following. During the last ten days of each preliminary period, the pigs were in their pens, fully harnessed, in order that they might have sufficient time to become accustomed to the experimental conditions before any data were recorded. CHEMICAL COMPOSITION OF FEEDS AND FECES ; AND WEIGHTS OF PIGS, FEEDS, WATER, FECES, AND URINE The chemical composition of the feeds and fresh feces are given in Tables 1 and 3, respectively. The weights of the pigs, the feeds, the water, the feces, and the urine for each experimental period are given in Table 2. From the data given in Table 2, it will be noted that the weights of the feces per pound of feed varied markedly depending upon the 1917] DIGESTIBILITY OF MIXED FEEDS ; INDIVIDUALITY OF PIGS 57 character of the ration. The average weights of the fresh feces per pound of feed were as follows: In Periods 1 and 2, and 7 and 8, in which middlings alone were fed, 1.13 and 0.99 pounds, respectively; in Periods 3 and 4, in which middlings and ground corn in the ratio of 1 to 1 were fed, 0.74 pounds ; in Periods 9 and 10, in which tank- age and ground corn in the ratio of 1 to 7.5 were fed, 0.39 pounds; and in Periods 5 and 6, in which ground corn alone was fed, 0.355 pounds. Examination of Table 3, giving the composition of the fresh feces, and of Table 4, showing the coefficients of digestibility of the nutrients of the rations, shows that the above differences in weights of the feces per pound of feed due to the character of the ration consumed, can be traced, in large part at least, to the variations in the water content of the feces and to the variations in the coefficients of digestibility of the dry substance of the rations. Thus, the average water content of the feces for the several periods wa"s as follows: Periods 1 and 2, and 7 and 8, in which middlings alone were fed, 79.83 and 76.51 per- cent, respectively; Periods 3 and 4, in which middlings and ground corn in the ratio of 1 to 1 were fed, 75.15 percent ; Periods 9 and 10, in which tankage and ground corn in the ratio of 1 to 7.5 were fed, 69.83 ; and Periods 5 and 6, in which ground corn alone was fed, 70.28 percent. The average coefficients of digestibility of the dry substance of the rations for the several periods were as follows : Periods 1 and 2, and 7 and 8, in which middlings alone were fed, 74.7 and 74.2, respectively ; Periods 3 and 4, in which middlings and ground corn in the ratio of 1 to 1 were fed, 79.1 ; Periods 9 and 10, in which tankage and ground corn in the ratio of 1 to 7.5 were fed, 86.8 ; and Periods 5 and 6. in which ground corn alone was fed, 87.9. TABLE 1. CHEMICAL COMPOSITION OF THE FEEDS (Results expressed in percent of the fresh substance) Nitro- Non- Kind of feed Used in periods Dry sub- stance gen- free ex- tract Crude fiber Crude pro- tein Ether ex- tract Crude ash pro- tein nitro- gen Total nitro- gen Ground corn .... Ground corn .... Average 3, 4, 5, 6 9,10 86.38 88.47 87.42 71.74 71.63 71.68 1.95 2.31 2.13 8.45 9.30 8.87 2.95 3.95 3.45 1.29 1.28 1.28 0.177 ' 0.156 0.166 1.352 1.489 1.420 Wheat flour middlings. . . . Wheat flour 1,2 89.64 54.98 5.92 18.33 5.85 4.58 0.615 2.932 middlings. . . . Average 3, 4, 7, 8 89.95 89.79 54.98 54.98 6.01 5.97 18.06 18.19 6.05 5.95 4.75 4.66 0.631 0.623 2.890 2.911 Tankasre. . 9.10 92.06 3.96 3.10 62.58 7.56 14:84 3.382 10.013 58 BULLETIN No. 200 [May, TABLE 2. WEIGHTS OF PIGS, FEEDS, WATER, FECES, AND URINE (Eesults expressed in pounds) Feeds consumed Feces Per Pig Live weight Mid- dlings Ground corn Total day per 100 Ibs. Water Total feces per Ib.of feed Total urine 1 live weight First Test Period. December 18 to 27, 1913. Ten days. Middlings 113 181.8 39.60 39.60 2.18 158.40 44.67 1.13 213 181.5 39.60 39.60 2.18 158.40 48.31 1.22 313 149.4 33.00 33.00 2.21 132.00 37.50 1.14 413 149.3 33.00 33.00 2.21 132.00 35.23 1.07 Average 165.5 36.30 36.30 2.20 145.20 41.43 1.14 Second Test Period. December 28, 1913 to January 6, 1914. Ten days. Middlings 113 186.5 39.60 39.60 2.12 15840 45.37 1 15 213 186.7 39.60 39.60 2.12 158.40 46.39 1.17 313 153.1 33.00 33:00 2.16 132.00 35.95 1.09 413 154.5 33.00 33:00 2.14 132.00 35.36 1.07 Average 170.2 36.30 36.30 2.14 145.20 40.77 1.12 Third Test Period. January 24 to February 2, 1914. Ten days. Middlings and ground corn (1 to 1) 113 213 313 413 207.0 207.6 174.3 172.4 22,0'0 22.00 18.00 18.00 22.00 22.00 18.00 18.00 44.00 44.00- 36.00 36:00 2.13 2.12 2.07 2.09 176.00 176.00 144.00 144.0,0 31.99 32.33 25.72 26.18 0.73 0.73 0.71 0.73 120.04 2 136.38 113.05 114.32 Average 190.3 20.00 20.00 40.00 2.10 160.00 29.05 0.72 120.95 Fourth Test Period. February 3 to 12, 1914. Ten days. Middlings and ground corn (1 to 1) 113 213 313 413 213.2 212.0 177.0 175.7 22.00 22.00 18.00 18.00 22.00 22.00 IS.0'0 18.00 44.00 44.00 36.00 36.00 2.06 2.08 2.03 2.05 176:00 176.00 144.00 144.00 33.84 33.63 26.51 27.54 0,77 0.76 0.74 0.76 134.42 136.80 -104.86' 90.84' Average 194.5 20.00 20.00 40.00 2.06 160.00 30.38 0.76 116.73 Fifth Test Period. March 7 to 17, 1914. Ten days. Ground corn 113 213 313 413 228.0 231.4 193.3 192.5 48.00 48:00 40.00 40.00 48.00 48.00 40.00 40.00 2.11 2.07 2.07 2.08 180.90 164.70 157.10 120.00 17.12 18.85 13.62 13.58 0.36 0.39 0.34 0.34 153.95 143.64 136.69 103.71 Average 211.3 44.00 44.00 2.08 155.67 15.79 0.36 134.50 1 Weight of urine for first and second periods not recorded. 2 Weight for 9 days only. 'Weight for 8 days only. 1917] DIGESTIBILITY OP MIXKD FEEDS; INDIVIDUALITY OF PIGS 59 TABLE 2. Concluded Pig Live weight Feeds consumed Water Total feces Feces per Ib.of feed Total urine Mid- dlings Ground corn Total Per day per 100 Ibs. live weight Sixth Test Period. March 18 to 27, 1914. Ten days. Ground corn 113 234.2 48.00 48.00 2.05 160.40 16.80 0.35 137.19 213 236.0 48.00 48.00 2.03 181.80 17.97 0.37 155.07 313 197.3 40,00 40.00 2,03 160.00 13:07 0.33 140.35 413 196.8 40.00 40.00 2.03 125.50 14.00 0.35 111.10 Average 216.1 44.00 44.00 2.04 156.92 15.46 0.35 135.93 Seventh Test Period. April 26 to May 5, 1914. Ten days. Middlings 113 283.0 52.00 52.00 1.84 208.00 57.00 1.10 150.94 213 283.2 52.00 52:00 1.84 208.00 52.66 1.01 155.93 313 248.3 46.00 46,00 1.85 184.00 45.57 0.99 140.66 413 240.8 46.00 46.00 1.91 184.00 46.89 1.02 142.76 Averasre 263.8 49.00 49.00 1.86 196.00 50.53 1.03 147.57 Eighth Test Period. May 6 to 15, 1914. Ten days. Middlings 113 213 313 413 292.3 290.7 255.3 247..7 52.00- 52,00 46.00 46.00 52.00 52.00 46.00 46.0'0 1.78 1.79 1.80 1.86 208.0 208.0 184.0 184.0 51.64 50.14 44.67 40.94 0.99 0.96 0.97 0.89 155.32 155.81 142.21 143.65 Average 271.5 49.00 49.00 1.81 196.0 46.85 0.95 149.25 Ninth Test Period. June 5 to 14, 1914. Ten days. Tankage and ground corn (1 to 7.5) 113 213 313 413 332.0 332.7 292.4 283.4 8.00 8.00 6.60 6.60 60.00 60.00 50.00 50.00 68.00 68.00 56.60 56.60 2.05 2.04 1.94 2.00 210.50 201.00 191.20 176.60 24.57 29.72 21.10 23.59 0.36 0.44 0.37 0.42 100.62 102.91 110.28 113.20 Average 310.1 7.30 55.00 62.30 2.01 194.82 24.74 0.40 106.75 Tenth Test Period. June 15 to 24, 1914. Ten days. Tankage and ground corn (1 to 7.5) 113 213 313 413 347.4 346.4 302.6 297.1 8.00 8.00 6.60 6.60 60.00 60.00 50.00 50.00 68.00 68.00 56.60 56.60 1.96 1.96 1.87 1.91 205.10 193.50 191.80 157.70 26.04 29.40 19.59 21.43 0.38 0.43 0.35 0.38 126.70 119.02' 127.79 98.03 Average 323.4 7.30 55.00 62.30 1.93 187.02 24.11 0.38 117.88 60 BULLETIN No. 200 [May, TABLE 3. CHEMICAL COMPOSITION OF THE FECES (Eesults expressed in percent of fresh substance) Nitro- Non- Nitro- Dry gen- Crude Ether pro- Total gen in- Pig sub- free Crude pro- ex- Crude tein nitro- soluble stance ex- fiber tein tract ash nitro- gen in acid tract gen pepsin First Test Period. December 18 to 27, 1913. Ten days. Middlings 113 213 313 413 19.64 19.34 18.88 21.08 8.05 7.99 7.84 8.89 4.12 3.87 3.97 4.14 3.47 3.39 3.14 3.79 0.93 1.07 0.88 1.06 3.02 3.03 3.06 3.20 0.161 0.157 0.158 0.163 0.555 0.542 0.502 0.607 0.205 0.213 0.210 0.198 Average 19.74 8.19 4.02 3.45 0.98 3.08 0.160 0.551 0.206 Second Test Period. December 28, 1913 to January 6, 1914. Ten days. Middlings 113 213 313 413 19.34 19.78 21.07 22.23 8.35 8.61 9.46 10.39 4.02 4.07 4.63 3.64 3.19 3.20 2.94 3.83 0.66 0.88 0.76 1.11 3.13 3.03 3.27 3.26 0.189 0.172 0.140 0.140 0.510 0.511 0.471 0.590 0.205 0.194 0.208 0.187 Average 20.60 9.20 4.09 3.29 0.85 3.17 0.160 0.520 0.198 Third Test Period. January 24 to February 2, 1914. Ten days. Middlings and ground corn (1 to 1) 113 213 313 413 25.38 25.39 24.28 24.71 12.62 12.62 11.77 11.62 4.48 4.27 4.96 4.82 3.97 4.24 3.42 4.55 1.34 1.31 0.80 0.73 2.97 2.95 3.34 3.01 0.129 0.129 0.098 0.130 0.635 0.678 0.546 0.727 0.228 0.201 0.293 0.260 Average 24.94 12.16 4.63 4.04 1.04 3.07 0.121 0.646 0.245 Fourth Test Period. February 3 to 12, 1914! Ten days. Middlings and ground corn (1 to 1) 113 24.61 11.25 5.23 3.78 1.29 3.06 0.129 0.605 0.224 213 24.28 12.05 4.35 4.10 0.93 2.85 0.152 0.655 0.181 313 25.18 12.00 5.31 3.93 0.79 3.14 0.207 0.628 0.183 413 25.01 12.08 4.76 4.51 0.87 2.85 0.177 0.721 0.257 Average 24.77 11.85 4.91 4.08 0.97 2.97 0.166 0.652 0.211 Fifth Test Period. March 7 to 17, 1914. Ten days. Ground corn 113 27.41 13.90 3.98 5.49 1.39 2.66 0.180 0.878 0.206 213 29.43 13.77 3.91 6.08 3.21 2.46 0.172 0.973 0.183 313 29.83 15.92 3.43 5.90 1.80 2.76 0.177 0.944 0.219 413 29.25 13.65 4.03 5.84 3.18 2.56 0.170 0.935 0.210 Average 28.98 14.31 3.84 5.83 2.39 2.61 0.175 0.932 0.204 1917 J DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF Pies TABLE 3. Concluded 61 Nitro- Non- Nitro- Dry gen- Crude Ether pro- Total gen in- Pig sub- free Crude pro- ex- Crude tein nitro- soluble stance ex- fiber tein tract ash nitro- gen in acid tract gen pepsin Sixth Test Period. March 18 to 27, 1914. Ten Days. Ground corn 113 213 313 413 29.71 31.52 29.41 31.21 16.08 15.33 14.49 16.03 3.67 4.15 3.41 3.88 5.53 6.58 6.12 6.06 1.49 2.78 2.51 2.46 2.94 2.67 2.87 2.79 0.257 0.223 0.238 0.239 0.884 1.053 0.979 0.969 0.216 0.188 0.234 0.290 Average 30.46 15.48 3.78 6.07 2.31 2.82 0.239 0.971 0.232 Seventh Test Period. April 26 to May 5, 1914. Ten days. Middlings 113 213 313 413 21.90 23.79 22.73 24.58 10.13 11.66 11.03 11.63 4.63 4.40 4.60 5.00 3.41 3.76 3.08 3.85 0.60 0.68 0.73 0.83 3.14 3.29 3.30 3.27 0.204 0.241 0.166 0.199 0.545 0.602 0.492 0.617 0.158 0.174 0.194 0.209 Average 23.25 11.11 4.66 3.52 0.71 3.25 0.202 0.564 0.184 Eighth Test Period. May 6 to 15, 1914. Ten days. Middlings 113 213 313 413 22.29 23.61 23.68 25.34 9.96 10.91 10.73 11.59 4.96 5.02 4.97 5.34 3.52 3.65 3.27 4.04 0.43 0.63 0.73 0.89 3.41 3.40 3.58 3.49 0.201 0.198 0.146 0.207 0.563 0.583 0.523 0.647 0.206 0.207 0.196 0.217 Average 23.73 10.80 5.07 3.62 0.67 3.47 0.188 0.579 0.206 Ninth Test Period. June 5 to 14, 1914. Ten days. Tankage and ground corn (1 to 7.5) 113 31.33 13.12 3.34 9.46 1.61 3.80 0.340 1.514 0.408 213 28.51 11.51 3.25 9.59 1.23 2.93 0.388 1.535 0.484 313 29.78 11.52 2.98 10.40 0.90 3.99 0.351 1.664 0.771 413 30.92 13.08 3.19 9.73 2.09 2.82 0.303 1.557 0.493 Average 30.14 12.31 3.19 9.80 1.46 3.38 0.346 1.568 0.539 Tenth Test Period. June 15 to 24, 1914. Ten days. Tankage and ground corn (1 to 7.5) 113 30.85 12.92 2.97 9.38 1.53 4.05 0.386 1.501 0.557 213 30.13 12.53 2.83 9.68 1.76 3.33 0.403 1.548 0.608 313 29.59 11.13 2.75 10.32 1.57 3.83 0.371 1.652 0.725 413 30.22 12.05 2.89 10.17 1.96 3.14 0.369 1.628 0.579 Average 30.20 12.16 2.86 9.89 1.70 3.59 0.382 1.582 0.617 COEFFICIENTS OF. DIGESTIBILITY OF THE NUTRIENTS OF THE RATIONS The coefficients of the digestibility of the nutrients of the rations for the four pigs, as determined directly, for the ten periods of this series of experiments are given in Tables 4 and 5. Wheat Flour Middlings. It is evident from Table 4 that the coefficients of the digestibility of the nutrients of wheat flour mid- dlings, when fed alone in Periods 1, 2, 7, and 8, varied somewhat >62 BULLETIN No. 200 [May, for the different animals during the same experimental period. It is also apparent that the coefficients varied considerably for the same animal in the different periods. This is especially true of the ether extract and the crude fiber. It is possible that the differences in the coefficients for Periods 1 and 2, on the one hand, and Periods 7 and 8, on the other hand, are due to the differences in the age and the weight of the animals. The pigs were about four and one-half months older, and weighed about 100 pounds more, during Periods 7 and 8 than dur- ing Periods 1 and 2. The average coefficients of digestibility of the nutrients of wheat flour middlings when fed alone to each of the four pigs for the four ten-day periods (sixteen digestion trials) were as follows: dry sub- stance, 74.4; nitrogen-free extract, 81.2; crude fiber, 21.0; crude protein, 80.0 ; and ether extract, 85.5. Ground Corn. The coefficients of digestibility of the nutrients of ground corn fed alone, in Periods 5 and 6, varied somewhat for the different pigs during the same period. The average coefficients of the dry substance, the nitrogen-free extract, and the crude protein of the ground corn agreed very closely for the two periods ; the average values for the crude fiber and the ether extract did not vary much. The average coefficients of digestibility of the nutrients of the ground corn when fed alone to each of the four pigs for the two ten-day periods (eight digestion trials) were as follows: dry substance, 87.9; nitrogen-free extract, 92.7 ; crude fiber, 30.8 ; crude protein, 75.0 ; and ether extract, 71.6. The average coefficients of the nutrients of ground corn when fed alone in four digestion trials previously re- ported from this station 1 were as .follows: dry substance, 87.7; nitrogen-free extract, 93.6; crude fiber, 31.8; crude protein, 79.3; and ether extract, 71.3. On comparing the average coefficients of the nutrients of the ration of ground corn fed alone with the corresponding averages for the ration of wheat flour middlings fed alone, it will be noted that the dry substance, the nitrogen-free extract, and the crude fiber of the ground corn were digested much more thoroly than the corresponding nutrients of the wheat flour middlings alone, while the crude protein and the ether extract of the ground corn were digested much less thoroly than those of the wheat flour middlings. Wheat Flour Middlings and Ground Corn (1 to 1). The co- efficients of digestibility of the nutrients of the ration of wheat flour middlings and ground corn fed together in the ratio of 1 to 1, in Periods 3 and 4, varied somewhat for the different animals during the same period. The average coefficients of digestibility of all the nutri- ents of this ration, except the crude fiber, agreed very closely for the two periods. Dietrich and Grindley: 111. Agr. Exp. Sta. Bui. 170. 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 63 The average coefficients of digestibility of the nutrients of the ra- tion of wheat flour middlings and ground corn fed together in the ratio of 1 to 1 to each of the four pigs for the two ten-day periods (eight digestion trials) were as follows: dry substance, 79.1 ; nitrogen- free extract, 85.9 ; crude fiber, 12.1 ; crude protein, 77.3 ; and ether extract, 83.4. On comparing the average coefficients of the nutrients of the ration of wheat flour middlings and ground corn fed together in the ratio of 1 to 1 with those of each of the rations of wheat flour middlings and of ground corn when fed alone, it will be noted that the coefficients of the nutrients for the ration of middlings and corn were in all cases, excepting that of the crude fiber, intermediate between those of the middlings fed alone and those of the corn fed alone. Tankage and Ground Corn (1 to 7.5) .The coefficients of digesti- bility of the nutrients of the ration of tankage and ground corn fed together in the ratio of 1 to 7.5, in Periods 9 and 10, varied signi- ficantly for the different pigs during the same period. The average coefficients of all the nutrients of this ration, except the crude fiber, agreed closely for the two experimental periods. The average coefficients of digestibility of the nutrients of the ration of tankage and ground corn fed together in the ratio of 1 to 7.5 to each of the four pigs for the two ten-day periods (eight digestion trials) were as follows : dry substance, 86.7 ; nitrogen-free extract, 92.5 ; crude fiber, 50.8 ; crude protein, 75.3 ; and ether extract, 85.8. The average coefficients of the nutrients of tankage and ground corn when fed together in ratios varying from 1 : 4 to 1 : 6 in six digestion trials previously reported from this station 1 were as follows: dry sub- stance, 83.2 ; nitrogen-free extract, 92.4 ; crude fiber, 19.0 ; crude pro- tein, 68.7 ; and ether extract, 76.4. On comparing the coefficients of the nutrients of this ration with those of wheat flour middlings when fed alone, it will be noted that the dry substance, the nitrogen-free extract, and the crude fiber of the tankage and corn were digested much more thoroly than those of the wheat flour middlings alone, while the crude protein was digested de- cidedly less thoroly. The coefficients of digestibility of the ether ex- tract were practically the same in the two rations. A comparison of the coefficients of the nutrients of this ration with those of the ration of ground corn fed alone shows that the dry sub- stance, the crude protein, and the nitrogen-free extract of the tank- age and corn were digested practically to the same extent as those of the ground corn alone, while the ether extract and the crude fiber of the tankage and corn were digested much more thoroly than those of the ground corn alone. 'Dietrich and Grindley: 111. Agr. Exp. Sta. Bui. 170. 64 BULLETIN No. 200 [May, TABLE 4. COEFFICIENTS OF DIGESTIBILITY Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract First Test Period. December 18 to 27, 1913. Ten days. Middlings 113 75.3 83.5 21.5 78.7 82.0 213 73.7 82.3 20.3 77.5 77.7 313 76.1 83.8 23.9 80.5 83.0 413 74.9 82.7 25.5 77.9 80.7 Average 75.0 83:.! 22.8 78.7 80.9 Second Test Period. December 28, 1913 to January 6, 1914. Ten Days. Middlings 113 75.3 82.6 22.3 80.1 87.2 213 74.2 81.7 19.6 79.6 82.5 313 74.4 81.3 14.9 82.5 85.8 413 73.4 79.7 34.1 77.6 79.6 Average 74.3 81.3 22.7 80.0 83.8 Third Test Period. January 24 to February 2, 1914. Ten days. Middlings and ground corn (1 to 1) 113 79.1 85.5 19.2 78.2 78.3 213 78.8 85.4 22.1 76.5 78.6 313 80.3 86.7 12.0 81.6 87.4 413 79.6 86.7 13.0 75.1 88.2 Average 79.5 86.1 16.6 77.9 83.1 Fourth Test Period. February 3 to 12, 1914. Ten days. Middlings and ground corn (1 to 1) 113 78.5 86.3 0.2 78.1 77.9 213 79.0 85.5 17.5 76.4 84.1 313 79.0 86.1 3.0 78.2 87.0 413 78.3' 85.4 9.6 74.0 86.1 Average 78.7 85.8 7.6 76.7 83.8 Fifth Test Period. March 7 to 17, 1914. Ten days. Ground corn 113 88.7 93.1 27.2 76.8 83.2 213 86.6 92.5 21.4 71.7 57.3 313 88.2 92.4 40.1 76.2 79.2 413 88.5 93.5 29.9 76.5 63.4 Average 88.0 92.9 29.7 75.3 70.8 Sixth Test Period. March 18 to 27, 1914. Ten days. Ground corn 113 88.0 92.2 34.2 77.1 82.3 213 86.3 92.0 20.3 70.8 64.8 313 88.9 93.4 42.9 76.3 72.1 413 87.4 92.2 30.4 74.9 70.8 Average 87.7 92.5 32.0 74.8 72.5 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS TABLE 4. Concluded 65 Pig Dry substance Nitrogen- free extract Crude fiber Cru3e protein Ether extract Seventh Test Period. April 26 to May 5, 1914. Ten days. Middlings 113 213 313 413 Average 73.3 73.2 74.9 72.1 73.4 79.8 78.5 80.1 78.4 79.2 15.5 26.0 18.3 15.3 18.8 79.5 79.1 83.3 78.4 80.1 89.0 88.5 87.8 85.8 87.8 Eighth Test Period. May 6 to 15, 1914. Ten days. Middlings 113 75.4 82.0 18.1 80.8 92.8 213 74.7 80.9 19.5 80.7 89.7 313 74.8 81.1 19.8 82.6 88.1 413 74.9 81.2 21:0 80.2 86.7 Average 75.0 81.3 19.6 81.1 89.3 Ninth Test Period. June 5 to 14, 1914. Ten days. corn (1 to 7.5) Tankage and ground 113 87.3 92.6 49.9 78.1 86.7 213 86.0 92.1 41.1 73.1 87.7 313 87.5 93.3 53.9 75.0 92.3 413 85.5 91.5 44.7 73.9 80.1 Average 86.6 92.4 47.4 75.0 86.7 Tenth Test Period. June 15 to 24, 1914. Ten days. corn (1 to 7.5) Tankage and ground 113 86.7 92.2 52.8 76.9 86.6 213 85.4 91.5 49.2 73.1 82.6 313 88.5 94.0 60.4 77.0 87.6 413 87.1 92.8 54.6 75.2 83.0 Average 86.9 92.6 54.3 75.6 85.0 THE INFLUENCE OF ONE FEED UPON THE DIGESTIBILITY OF THE NUTRIENTS OF ANOTHER FEED The doubtful values obtained in digestion experiments in our previous work and in the work of others, by determining indirectly, or by calculation, the coefficients of the nutrients for one feed by sub- tracting the weights of the digestible nutrients of another feed from the corresponding values for the two feeds combined, led us to plan these experiments to determine more accurately, if possible, the in- fluence of one feed upon the digestibility of the nutrients of another feed. From the results of practical feeding experiments some authors have taken the view that when feeds are fed singly, they are not as completely digested as when fed in mixed rations, because rations com- posed of a single feed are not as efficient for producing growth and fattening as mixed feeds. For example, whenever milk is added to a 66 BULLETIN No. 200 [May, TABLE 5. SUMMARY OF THE AVERAGE COEFFICIENTS OF DIGESTIBILITY CF THE EATIONS Period Dry sub- stance Nitro- gen-free extract Crude fiber Crude protein Ether extract Wheat flour middlings 1 75.0 83.1 22.8 78.7 80.9 Wheat flour middlings 2 74.3 81.3 22.7 80.0 83.8 Average 74.6 82.2 22.7 79.3 82.3 Wheat flour middlings 7 73.4 79.2 18.8 80.1 87.8 Wheat flour middlings 8 75.0 81.3 19.6 81.1 89.3 Average 74.2 80.2 19.2 80.6 88.5 Ground corn and middlings 3 79.5 86.1 16.6 77.9 83.1 Ground corn and middlings 4 78.7 85.8 7.6 76.7 83.8 Average 79.1 85.9 12.1 77.3 83.4 Ground corn 5 88.0 92.9 29.7 75.3 70.8 Ground corn 6 87.7 '92.5 32.0 74.8 72.5 Average 87 8 92 7 30 8 75.0 71.6 Tankage and ground corn 9 86 6 92 4 474 750 86 7 Tankage and ground corn 10 869 92.8 543 75.6 85 Average. . 86.7 92.6 50.8 75.3 85.8 ration composed of a single grain, a larger amount of pork is produced than when the same amount of nutrients from the single grain is fed. It has therefore been assumed by some authors that in such cases the increased production is due to the fact that the milk increased the digestibility of the grains with which it was fed. However, it has recently been proved that there are other factors that favor increased production where the mixed rations are fed. The data for the coefficients of digestibility of the nutrients of the wheat flour middlings, as determined directly when fed alone, and as calculated indirectly from the results of direct digestion experiments with the ration of middlings and ground corn and of the ground corn alone, are given in Table 6. It will be noted that the individual data and the average data for the four pigs show that the calculated values indirectly determined for the coefficients of digestibility of the dry substance and the nitrogen-free extract of the middlings are signifi- cantly lower than the corresponding coefficients of the nutrients of the middlings determined directly by the digestion experiments. The results indicate that there is no significant difference between the coefficients for the protein as calculated indirectly and as deter- mined directly. The results for the ether extract are very irregular, but the average results indicate that the calculated values for the co- efficients of the ether extract for the middlings are probably signifi- cantly higher than those determined directly by actual experiments. It is quite apparent from the experimental data here presented that the calculated coefficients for the crude fiber are very irregular as compared with those determined directly. 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS TABLE 6. COEFFICIENTS OF DIGESTIBILITY OF MIDDLINGS, DIRECTLY AND INDIRECTLY DETERMINED 67 Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Middlings fed alone. First Test Period 113 75.3 83.5 21.5 78.7 82.0 213 73.7 82.3 20.3 77.5 77.7 313 76.1 83.8 23.9 80.5 83.0 413 74.9 82.7 25.5 77.9 80.7 Average 75.0 83.1 22.8 78.7 80.8 Middlings calculated from middlings and corn ration. Third and Fifth Test Periods 113 69.9 75.6 16.6 78.9 75.9 213 71.4 76.1 22.4 78.7 89.0 313 72.2 79.3 3.0 84.1 91.4 413 71.1 77.7 7.6 74.4 100.3 Average 71.2 77.2 12.4 79.0 89.2 Middlings fed alone. Second Test Period 113 75.3 82.6 22.3 80.1 87.2 213 74.2 81.7 19.6 79.6 82.5 313 74.4 81.3 14.9 82.5 85.4 413 73.4 79.7 34.1 77.6 79.6 Average 74.3 81.3 22.7 79.9 83.7 Middlings calculated from middlings and corn ration. Fourth and Sixth Test Periods 113 69.5 78.8 -10.7 78.5 75.9 v 213 . 71.9 76.9 16.7 79.0 93.6 313 69.5 76.5 -9.8 79.1 94.3 413 69.8 76.6 2.9 73.5 93.6 Average 70.2 77.a -0.2 77.5 89.3 The data for the coefficients of digestibility of the nutrients of the ground corn as determined directly when fed alone, and as calculated indirectly from the direct experiments with the combined ration com- posed of middlings and ground corn and the wheat flour middlings alone, are given in Table 7. A study of these data leads in general to the same conclusions as to the variations and differences between the direct and indirect coefficients of the nutrients of the ground corn as were reached with regard to the direct and indirect values for wheat flour middlings. It should be said, however, that the calculated co- efficients for the crude fiber and the ether extract of the corn are more irregular than the corresponding calculated coefficients for the wheat flour middlings. The data for the coefficients of digestibility of the nutrients of the ration composed of one part of middlings and one part of ground 68 BULLETIN No. 200 [May, corn, as determined directly, and as calculated indirectly from the coefficients directly determined for middlings when fed alone and for ground corn when fed alone, are given in Table 8. It is apparent that the calculated coefficients for the ether extract of the ration are lower than those directly determined for the mixed ration. There is appar- ently no significant difference between the calculated coefficients and the directly determined coefficients for the protein of the mixed ration. It is thus evident from the individual data, as well as from the average results given in Tables 6 to 8, inclusive, that the digestibility of the nutrients of a ration composed of equal parts of wheat flour middlings and ground corn are not what they would be if the coeffi- cients of digestibility of the nutrients of each of the feeds when fed together had remained the same as they were in the individual feeds when fed alone. This difference between the directly and indirectly TABLE 7. COEFFICIENTS OF DIGESTIBILITY OF GROUND CORN, DIRECTLY AND INDIRECTLY DETERMINED Pig Dry substance Nitrogon- free extract Crude fiber Crude protein Ether extract Ground corn fed alone. Fifth Test Period 113 88.7 93.1 27.2 76.8 83.2 213 86.6 92.5 21.4 71.7 57.3 313 88.2 92.4 40.1 76.2 79.2 413 88.5 93.5 29.9 76.5 63.4 Average 88.0 92.9 29.6 75.3 70.8 ' Ground corn calculated from middlings and corn ration. First arid Third Test Periods 113 83.0 87.1 12.0 77.4 | 70.8 213 84.2 87.7 27.7 74.5 80.4 313 84.8 89.0 -25.3 83.9 96.5 413 84.5 89.7 -26.0 69:0 103.6 Average 84.1 88.4 -2.9 76.2 87.8 Ground corn fed alone. Sixth Test Period 113 88.0 92.2 34.2 77.1 82.3 213 86.3 92.0 20.3 70.8 64.8 313 88.9 93.4 42.9 76.3 72.1 413 87.4 92.2 30.4 74.9 70.8 Average 87.6 92.4 31.9 74.8 72.5 Ground corn calculated from middlings and corn ration. Second and Fourth Test Periods 113 81.9 89.2 -69.0 73.9 58.8 213 84.0 88.4 11.2 69.6 87.6 313 83.7 89.7 -34.2 69.6 89.0 413 83.4 89.8 -67.0 66.2 99.5 Average 83.3 89.3 -39.8 69.8 83.7 1917} DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 69 TABLE 8.- -COEFFICIENTS OF DIGESTIBILITY OF A RATION OF MIDDLINGS AND GROUND CORN (1 TO 1), DIRECTLY AND INDIRECTLY DETERMINED Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Middlings and ground corn (1 to 1) fed together, direct determination. Third Test Period 113 79.1 85.5 19.2 78.2 78.3 213 78.8 85.4 22.1 76.5 78.6 313 80.3 86.7 12.0 81.6 87.4 413 79.6 86.7 13.0 75.1 88.2 Average 79.5 86.1 16.G 77.9 83.1 Middlings and ground corn (1 to 1) calculated from the direct determinations of the middlings ration and the corn ration. First and Fifth Test Periods 113 81.9 88.9 22.9 78.1 82.4 213 80.0 88.1 20.6 75.7 70.9 313 82.0 88.7 27.9 79.1 81.7 413 81.6 88.8 26.6 77.5 74.9 Average 81.4 88.6 24.5 77.6 77.5 Middlings and ground corn (1 to 1) calculated from the indirect determinations for the corn ration and the middlings ration (see second sections of Tables 6 and 7) 113 76.3 82.1 15.5 78.4 74.2 213 77.7 82.7 23.7 77.4 86.1 313 78.4 84.8 -4.0 84.0 93.1 413 77.7 84.5 -0.7 72.7 101.4 Average 77.5 83.5 8.6 78.1 88.7 Middlings and ground corn (1 to 1) fed together, direct determination. Fourth Test Period 113 78.5 86.3 0.2 78.1 77.9 213 79.0 85.5 17.6 76.4 84.1 313 79.0 86.1 3.0 78.2 87.0 413 78.3 85.4 9.6 74.0 86.1 Average 78.7 85.8 7.6 76.7 83.8 Middlings and ground corn (1 to 1) calculated from the direct determinations of the corn ration and the middlings ration. Second and Sixth Test Periods 113 81.5 88.0 25.2 79.2 85.6 213 80.1 87.5 19.8 , 76.8 76.6 313 81.5 88.2 21.8 80.5 81.2 413 80.3 86.8 33.2 76.7 76.6 Average 80.8 87.6 25.0 78.3 80.0 Middlings and ground corn (1 to 1) calculated from the indirect determinations foi the corn ration and the middlings ration (see fourth sections of Tables 6 and 7) 113 75.6 84.7 -25.1 77.0 70.2 213 77.8 83.4 15.3 76.0 91.6 313 76.5 84.0 -15.8 75.9 92.5 413 76.5 84.1 -14.4 71.2 95.6 Average 76.6 84.0 -10.0 75.0 87.5 70 BULLETIN No. 200 [May, determined coefficients of the nutrients of the mixed ration may be due to one or the other of the following influences : First, it is pos- sible that either the wheat flour middlings or the ground corn in the mixed ration influences directly the digestibility of the nutrients of the other feed. Second, it is possible, on the other hand, that there is a mutual influence of each feed upon the other, which results in decreas- ing the digestibility of the dry substance, the nitrogen-free extract, and the crude fiber; and in increasing the digestibility of the ether extract of the mixed ration. INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGEST THEIR FEED From the preceding results it was possible to study the question of the individuality of pigs as to the thoroness with which they digest their feed. The influence of the individual peculiarities of experi- mental animals upon the thoroness of digestion of their feed is a mat- ter of considerable interest. Very often when the same ration is fed to three or more animals of the same species, as many different coeffi- cients of digestibility are obtained for the same nutrient as there are animals. The variations are usually not great, but they nearly always occur, and the question arises as to the part which the factor of indi- viduality plays in producing these variations. The data for the coefficients of digestibility of the crude protein obtained in forty digestion trials, of ten days each, in which four rations were fed to each of four pigs, are given in Table 9. Examina- tion of the data shows that the individual coefficients for Pig 313 are significantly greater than the individual coefficients for Pig 213, in each of the ten experimental periods. A similar comparison of the coefficients of digestibility of protein for Pigs 313 and 413 shows a similar significant difference. Since conditions thruout the experi- ment were practically identical, the data lead clearly to the conclu- sion that, altho the pigs were litter mates and were fed together from birth, individuality was shown by a distinct and well-defined differ- ence between the coefficients of digestibility of crude protein for Pig 313 and Pigs 213 and 413 thruout the ten experiments. A fur- ther study of the data in this table shows that for Pigs 113 and 213 and for Pigs 113 and 413 there was a considerable, tho less marked, difference in the coefficients of digestibility of crude protein which apparently can be assigned to the factor of individuality; but that there are practically no differences in the coefficients of digestibility of crude protein for Pigs 213 and 413 or for Pigs 113 and 313, that can be considered as due to the factor of individuality. Examination of the data given in Table 9 for the coefficients of the dry matter, the nitrogen-free extract, and the ether extract shows in general the same individual differences as were found in the coeffi- 19171 DIGESTIBILITY OF MIXED FEEDS;. INDIVIDUALITY OF PIGS 71 TABLE 9. SUMMARY OF THE COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS SHOWING THE INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGESTED THEIR FEED Period Ration Pig 313 Pig 113 Pig 413 Pig 213 Pig 313 Pig 113 Pig 413 Pig 213 Crude protein Ether extract 1 2 7 8 3 4 5 6 9 10 Middlings (alone) Middlings (alone) 80.5 82.5 83.3 82.6 81.6 78.2 76.2 76.3 75.0 77.0 79.3 78.7 80.1 79.5 80.8 78.2 78.1 76.8 77.1 78.1 76.9 78.4 77.9 77.6 78.4 80.2 75.1 74.0 76.5 74.9 73.9 75.2 76.4 77.5 79.6 79.1 80.7 76.5 76.4 71.7 70.8 73.1 73.1 75.8 83.0 85.8 87.8 88.1 87.4 87.0 79.2 72.1 92.3 87.6 85:0 82.0 87.2 89.0 92.8 78.3 77.9 83.2 82.3 86.7 86.6 84.6 80.7 79.6 85.8 86.7 88.2 86.1 63.4 70.8 80.1 83.0 80.4 77.7 82.5 88.5 89.7 78.6 84.1 57.3 64.8 87.7 82.6 79.3 Middlings (alone) Middlings (alone) Middlings and corn (1 to 1) ... Middlings and corn (1 to 1) ... Corn (alone) Corn (alone) Tankage and corn (1 to 7.5) .... Tankage and corn (1 to 7.5) .... Average Dry substance | Nitrogen-free extract 1 2 7 8 3 4 5 6 9 10 Middlings (alone) 76.1 74.4 74.9 74.8 80.3 79.0 88.2 88.9 87.5 88.5 81 3 75.3 75.3 73.3 75.4 79.1 78.5 88.7 88.0 87.3 86.7 808 74.9 73.4 72.1 74.9 79.6 78.3 88.5 87.4 85.5 87.1 80?, 73.7 74.2 73.2 74.7 78.8 79.0 86.6 86.3 86.0 85.4 798 83.8 81.3 80.1 81.1 86.7 86.1 92.4 93.4 93.5 94.2 873 83.5 82.6 79.8 82.0 85.5 86.3 93.1 92.2 92.8 92.5 87.0 82.7 7-9.7 78.4 81.2 86.7 85.4 93.5 92.2 91.7 93.1 865 82.3 81.7 78.5 80.9 85.4 85.5 92.5 92.0 92.4 91.8 863 Middlings (alone) Middlings (alone) Middlings (alone) Middlings and corn (1 to 1) ... Middlings and corn (1 to 1) ... Corn (alone) Corn (alone) Tankage and corn (1 to 7.5) .... Tankage and corn (1 to 7.5) .... Average . . eients of digestibility of the crude protein for the four pigs. How- ever, the individuality of these pigs with reference to their power of digesting dry matter, nitrogen-free extract, and ether extract is not so clearly evident as it was in the case of crude protein. It is apparent, therefore, that in this series of experiments, all with the same animals, in which different rations were used in the different experiments, the coefficients as a whole showed constantly higher values for some animals than for other animals. Such consistent dif- ferences under such conditions must be attributed to the individuality of the different animals. The total gains in weight of the four pigs during the ten experi- mental periods, each of ten days' duration, during which time each of the four animals received the same kinds of feed and the same quan- tities of feed per 100 pounds of live weight, were as follows : Pig 113, 79 pounds ; Pig 213, 74 pounds ; Pig 313, 57 pounds ; and Pig 413, 65 pounds. The average live weights of the pigs during the ten ex- perimental periods were as follows : Pig 113, 250.5 pounds ; Pig 213, 250.8 pounds ; Pig 313, 214.3 pounds ; and Pig 413, 211.0 pounds. The weights of the total feeds consumed during this same time were as follows : Pig 113, 503.2 pounds ; Pig 213, 503.2 pounds ; Pig 313, 423.2 pounds; and Pig 413, 423.2 pounds. The weights of feed re- 72 BULLETIN No. 200 [May, quired to produce 100 pounds of gain during the ten experimental periods were as follows: Pig 113, 637 pounds; Pig 218, 680 pounds; Pig 313, 743 pounds; and Pig 413, 651 pounds. Comparing these gains in weight and the economy of the gains in weight with the aver- age coefficients of digestibility of the nutrients of the feeds for each animal, it will be noted that there is no consistent correlation between the coefficients of digestibility and the gains, or the economy of gains, in weight. For example, Pig 113, which on the average digested all of the nutrients of the feeds more thoroly than did Pig 213 (which weighed the same and consumed an equal quantity of the same feeds as Pig 113) made a gain of 79 pounds and required 637 pounds of feed to produce 100 pounds of gain ; while Pig 213 gained 74 pounds and required 680 pounds of feed to produce 100 pounds of gain. On the other hand, Pig 313, which on the average digested all of the nutrients of the feeds more thoroly than did Pig 413 (which weighed the same and consumed an equal quantity of the same feeds as Pig 313) made a gain of only 57 pounds and required 743 pounds of feed to produce 100 pounds of gain ; while Pig 413 gained 65 pounds and required 651 pounds of feed to produce 100 pounds of gain. This study clearly shows that different animals of the same species may show individuality as to the thoroness with which they digest the nutrients of their feeds. However, such differences in the coefficients of digestibility of the nutrients of the same feeds by different animals are probably too 'small to be considered of practical or economic im- portance. SECOND SERIES OF EXPERIMENTS, 1914-1915 PLAN Four cross-bred Duroc Jersey-Poland China barrows of the same age as the pigs used in the first series of experiments namely, a few days over seven months, and all from the same litter were selected for this second series of experiments. The pens, feed troughs, and digestion harness were the same as those used in the first experiments. In the second series ground barley (malting) was substituted for the wheat flour middlings used in the first series, but the ratio of feed to the live weight of the animals, the length of the transitional, the pre- liminary, and the test periods, and the general management and treat- ment of the animals were the same. The weather conditions during Ihe two series of experiments were also similar. The first ration for which the coefficients of digestibility were de- termined consisted of 2.08 pounds of ground barley (malting) per ]00 pounds live weight; the second, of 1.05 pounds of ground barley and 1.05 pounds of ground corn (No. 2 yellow) per 100 pounds live weight ; the third, of 2.12 pounds of ground corn per 100 pounds live weight; and the fourth, of 1.80 pounds of ground corn and 0.24 pounds of digester tankage per 100 pounds live weight. Each of these 1917} DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 73 rations was fed for two ten-day periods, during which time samples of the feeds and the feces were taken for chemical analysis. CHEMICAL COMPOSITION OF FEEDS AND FECES; AND WEIGHTS OF PIGS, FEEDS, WATER, FECES, AND URINE The chemical composition of the feeds and the fresh feces are given in Tables 10 and 12, respectively. The weights of the pigs, the feeds, the water, the feces, and the urine are presented in Table 11. From the experimental data given in Table 11, it will be noted that the weights of the feces per pound of feed varied markedly de- pending upon the character of the ration. Thus the average weights of the fresh feces per pound of feed were as follows: in Periods 1 and 2, in which ground barley was fed, 0.96 pound; in Periods 3 and 4, in which ground barley and ground corn in the ratio of 1 to 1 were fed, 0.68 pound; in Periods 7 and 8, in which tankage and ground corn in the ratio of 1 to 7.5 were fed, 0.41 pound; and in Periods 5 and 6, in which ground corn was fed, 0.36 pound. Examination of the data of Table 12, giving the composition of the fresh feces, and of Table 13, showing the coefficients of digestibil- ity of the nutrients of the rations, shows that the differences mentioned above in the weights of the feces per pound of feed due to the charac- ter of the ration consumed can be traced, in large part at least, as in the first experiments, to the variations in the water content of the feces, and to the variations in the coefficients of digestibility of the dry substance of the rations. Thus, the average water content of the feces for the several periods was as follows : Periods 1 and 2, in which ground barley alone was fed, 72.20 percent ; Periods 3 and 4, in which ground barley and ground corn in the ratio of 1 to 1 were fed, 74.91 percent; Periods 7 and 8, in which tankage and ground corn in the ratio of 1 to 7.5 were fed, 68.81 percent ; and Periods 5 and 6, in which ground corn alone was fed, 67.74 percent. The average coefficients of TABLE 10. CHEMICAL COMPOSITION OF THE FEEDS (Eesults expressed in percent of the fresh substance) Kind of feed Used in periods Dry sub- stance Nitro- gen-free extract Crude fiber Crude protein Ether extract Crude ash Total nitro- gen Ground corn. . Ground corn. . Ground corn. . Average. . . . Barley 3,4 5,6 7,8 1,2 86.32 83.94 86.22 85^49 91.00 69.85 68.17 71.37 69.80 67 06 3.73 2.06 2.29 2.69 402 9.51 9.15 9.31 9.32 14 80 3.73 3.37 2.06 3.05 2 35 1.17 1.18 1.19 1.18 2 77 1.522 1.464 1.489 1.492 2 368 Barlev 3,4 91.07 70.04 496 11 29 2 14 2 65 1 806 Average. . . . Tankage. . 7.8 91.03 88.65 68.55 12.51 4.49 5.33 13.04 58.53 2.24 8.15 2.71* 15.49 2.087 9.364 BULLETIN No. 200 TABLE 11. WEIGHTS OP PIGS, FEEDS, WATER, FECES, AND URINE (Results expressed in pounds) [May, Feeds consumed Per Feces Live day Total per Total Pig weight Ground per Water feces Ib.of urine Barley corn Total 100 Ibs. feed live weight First Test Period. November 27 to December 6, 1914. Ten days. Barley 114 214 314 414 Average 217.1 182.4 174.1 158.9 183.1 45.00 38.40 37.40 33.00 38.45 45.00 38.40 37.40 33.00 38.45 2.07 2.11 2.15 2.08 2.10 143.40 122.40 119.00 105.00 ' 122.45 39.01 36.23 35.33 32.17 35.68 0.87 0.94 0.94 0.97 0.93 100.76 83.41 80.12 68.39 83.17 Second Test Period. December 7 to 16, 1914. Ten days. Barley 114 214 314 414 Average 222.9 187.4 177.9 162.4 187.6 45.00 38.40 37.40 33.00 38.45 ::::: 45.00 38.40 37.40 33.00 38.45 2.02 2.05 2.10 2.03 2.05 143.40 122.40 119.00 105.00 122.45 41.92 37.07 37.42 34.99 37.85 0.93 0.97 1.00 1.06 0.99 106.27 86.00 74.54 67.97 83.69 ..... Third Test Period. January 17 to 26, 1915. Ten days. Barley and ground corn (1 to 1) 114 242.6 26.00 26.00 52.00 2.14 164.00 33.60 0.65 133.64 214 203.6 21.50 21.50 43.00 2.11 136.00 30.31 0.71 108.01 314 190.9 20.00 20.00 40.00 2.10 130.00 27.05 0.68 99 V 57 414 173.4 18.50 18.50 37.00 2.13 116.00 26.26 0.71 86.99 Average 202.6 21.50 21.50 43.00 2.12 136.50 29.30 0.69 107.05 Fourth Test Period. January 27 to February 5, 1915. Ten days. Barley and ground corn (1 to 1) 114 214 314 414 247.6 207.4 195.6 177.1 26.00 21.50 20.00 18.50 26.00 21.50 20.00 18.50 52.00 43.00 40.00 37.00 2.10 2.07 2.04 2.09 164.00 136.00 130.00 116.00 31.96 28.77 26.22 26.94 0.62 0.67 0.66 0.73 132.65 108.45 100.16 87.68 Average 206.9 21.50 21.50 43.00 2.07 136.50 28.47 0.67 107.23 Fifth Test Period. March 6 to 15, 1915. Ten days. Ground corn 114 214 314 414 280.9 230.9 218.1 201.1 60.00 48.60 47.60 43.80 60.00 48.60 47.60 43.80 2.14 2.10 2.18 2.18 194.00 158.00 156.00 142.00 20.47 17.38 17.16 17.45 0.34 0.36 0.36 0.40 170.82 139.98 135.55 118.51 Average 232.7 50.00 50:00 2.15 162.50 18.11 0.33 141.21 1917] DIGESTIBILITY OF MIXED 'FEEDS; INDIVIDUALITY OF PIGS TABLE 11. Concluded Feeds consumed Per Feces Pig Live weight Tank- age Ground corn Total day per 100 Ibs. Water Total feces per Ib. of feed Total urine live weight Sixth Test Period. March 16 to 25, 1915. Ten days. Ground corn 114 290.1 60.00 60.00 2.07 194.00 21.35 0.36 172.29 214 239.1 48.60 48.60 2.03 158.00 15.72 0.32 140.30 314 225.6 47.60 47.60 2.11 156,00 16.69 0.35 132.43 414 207.6 43.80 43.80 2.11 142.00 17.04 0.39 117.51 Average 240.6 50.00 50.00 2.08 162.50 17.70 0.37 140.63 Seventh Test Period. April 22 to May 1, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 352.6 8.54 64.06 72.60 2.06 220.00 30.84 0.42 173.22 214 286.9 6.87 51.53 58.40 2.04 182.00 21.43 0.37 139.52 314 275.6 6.70 50.30 57.00 2.07 178.00 22,97 0.40 130.58 414 256.1 6.35 47.65 54.00 2.11 172.00 21.40 0.40 ' 133.61 Average 292.8 7.11 53.38 60.50 2.07 188.00 24.16 0.40 144.23 Eighth Test Period. May 2 to 11, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 366.4 8.54 64.06 72.60 1.98 220.00 30.47 0.42 173.22 214 300.6 6.87 51.53 58.40 1.94 182.00 21.76 0.37 153.09 314 288.4 6.70 50.30 57.00 1.98 178.00 26.07 0.46 146.16 414 267.4 6.35 47.65 54.00 2.02 172.00 23.71 0.44 141.06 Average 305.7 7.11 53.38 60.50 1.98 188.00 25.50 0.42 153.38 digestibility of the dry substance of the rations for the several periods were as follows : Periods 1 and 2, in which ground barley alone was fed, 70.8 ; Periods 3 and 4, in which ground barley and ground corn in the ratio of 1 to 1 were fed, 80.9 ; Periods 7 and 8, in which tank- age and ground corn in the ratio of 1 to 7.5 were fed, 85.3 ; and Periods 5 and 6, in which ground corn alone was fed, 86.2. COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS OF THE RATIONS The coefficients of digestibility of the nutrients of the rations for the four pigs, as determined directly, for the eight experimental periods of this series of experiments are given in Tables 13 and 14. Ground Barley. It is evident from Table 13 that the coefficients of digestibility of the nutrients for ground barley, when fed alone in Periods 1 and 2, varied for the different animals during the same ex- perimental period. This is especially true of the coefficients for the crude fiber and the ether extract. It is also evident that the coeffi- cients varied considerably for the same animal in different periods. 76 BULLETIN No. 200 [May, TABLE 12. CHEMICAL COMPOSITION OF THE FECES (Results expressed in percent of fresh substance) Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Crude ash Total nitrogen First Test Period. November 27 to December 6, 1914. Ten days. Barley 114 214 314 414 27.86 27.86 29.13 26.81 14.03 13.43 13.94 11.79 3.67 3.66 3.59 3.88 6.77 6.69 7.58 7.13 0.95 1.82 1.79 1.83 2.45 2.26 2.24 2.18 1.083 1.070 1.213 1.141 Average 27.92 13.30 3.70 7.04 1.60 2.28 1.127 Second Test Period. December 7 to 16, 1914. Ten days. Barley 114 214 314 414 25.25 28.30 29.34 27.82 10.94 13.69 14.01 13.49 3.88 3.85 3.65 3.08 7.08 6.63 7.66 7.14 0.89 1.90 1.81 1.99 2.46 2.24 2.21 2.12 1.132 1.060 1.222 1.143 Average 27.68 13.03 3.62 7.13 1.65 2.26 1.139 Third Test Period. January 17 to 26, 1915. Ten days. Barley and ground corn (1 to 1) 114 214 314 414 24.97 24.16 24.95 23.15 11.97 11.52 10.86 10.21 4.41 4.48 5.12 4.34 4.82 4.85 5.15 5.29 0.88 0.99 1.47 1.13 2.45 2.31 2.35 2.18 0.771 0.776 0.824 0.846 Average 24.30 11.14 4.59 5.03 1.12 2.32 0.804 Fourth Test Period. January 27 to February 5, 1915. Ten days. Barley and ground corn (1 to 1) 114 214 314 414 25.80 25.86 27.02 24.80 11.93 12.34 12.68 11.18 4.67 4.31 4.25 4.41 5.10 5.37 5.47 5.22 1.66 1.22 2.25 1.79 2.44 2.61 2.37 2.19 0.816 0.859 0.875 0.835 Average 25.87 12.03 4.41 5.29 1.73 2.40 0.846 Fifth Test Period. March 6 to 15, 1915. Ten days. Ground corn 114 214 314 414 31.59 31.94 33.27 31.10 16.26 16.76 16.65 15.35 3.62 3.41 3.52 3.49 6.77 6.49 6.86 6.23 2.15 2.62 3.71 3.52 2.79 2.66 2.56 2.52 1.083 1.012 1.098 0.997 Average 31.98 16.26 3.51 6.59 3.00 2.63 1.048 Sixth Test Period. March 16 to 25, 1915. Ten days. Ground corn 114 214 314 414 32.64 32.04 33.66 31.80 16.03 16.90 16.26 15.32 3.58 3.50 3.52 3.44 6.99 6.38 7.01 6.31 3.33 2.54 4.12 4.16 2.72 2.72 2.75 2.56 1.118 1.020 1.121 1.010 Average 32.54 16.13 3.51 6.67 3.54 2.69 1.067 1917} DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 77 TABLE 12. Concluded Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Crude ash Total nitrogen Seventh Test Period. April 22 to May 1, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 32.39 13.24 3.20 9.78 1.73 4.42 1.565 214 30.28 12.17 2.93 9.80 1.81 3.58 1.568 314 31.67 13.33 3.24 9.23 2.13 3.74 1.476 414 32.85 14.26 3.27 9.76 1.45 4.11 1.561 Average 31.80 13.25 3.16 9.64 1.78 3.96 1.543 Eighth Test Period. May 2 to 11, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 27.90 10.03 3.10 9.28 1.19 4.31 1.484 214 29.87 12.14 2.85 9.68 1.19 4:02 1.548 314 32.14 14.18 3.15 9.12 1.78 3.93 1.459 414 32.40 14.09 3.30 9.27 1.82 3.89 1.483 Average 30.58 12.61 3.10 9.34 1.50 4.04 1.494 The average coefficients of digestibility of the nutrients of ground barley when fed alone to the four pigs for the two ten-day periods (eight digestion trials) were as follows : dry substance, 70.8 ; nitrogen- free extract, 81.2 ; crude fiber, 14.1 ; crude protein, 54.0 ; and ether extract, 33.0. Ground barley was the least digestible of any of the rations used in this experiment. The coefficients of digestibility of the crude protein, the ether extract, and the crude fiber were very low. Ground Corn. The coefficients of digestibility of the nutrients of ground corn fed alone in Periods 5 and 6 varied somewhat for the different pigs during the same period. The average coefficients of digestibility of all the nutrients, except those of the ether extract, agreed very closely for the two periods. The average coefficients of digestibility of the nutrients of the ground corn when fed alone to each of the four pigs for the two ten- day periods (eight digestion trials) were as follows: dry substance, 86.2; nitrogen-free extract, 91.5; crude fiber, 38.8; crude protein, 74.0 ; and ether extract, 64.9. These results for the dry substance, the <;rude protein, and the nitrogen-free extract agree closely with the cor- responding average results obtained in the eight digestion experiments with corn reported in the first series of experiments. On comparing the average coefficients of the nutrients of the ration of ground corn fed alone with the corresponding averages for the ration of ground barley fed alone, it will be noted that all of the nutrients of the ground corn were digested much more thoroly than those of the ground barley alone. Ground Barley and Ground Corn (1 to 1). The coefficients of digestibility of the nutrients of the ration of ground barley and ground 78 BULLETIN No. 200 [May, TABLE 13. COEFFICIENTS OF DIGESTIBILITY Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract First Test Period. November 27 to December 6, 1914. Ten Days. Barley 114 214 314 414 Average 73.5 71.9 69.8 71.3 71.6 81.9 81.1 80.4 82.9 81.6 20.9 14.0 15.5 5.9 1 16.8 60.4 57.4 51.6 53.0 55.6 64.9 27.2 28.2 24.1 36.1 Second Test Period. December 7 to 16, 1914. Ten days. Barley 114 214 314 414 Average 74.2 70.0 67.7 67.6 69.9 84.8 80.3 79.1 78.7 80.7 10.1 7.5 9.2 18.7 11.4 55.5 56.8 48.2 48.8 52.3 64.6 22.1 22.8 10.2 29.9 Third Test Period. January 17 to 26, 1915. Ten days. Barley and ground corn (1 to 1) 114 214 314 414 , Average 82.1 80.8 81.0 81.0 81.2 88.9 88.4 89.5 89.6 89.1 18.8 10.0 1.4* 12.3 13.7 70.1 67.1 66.5 63.9 66.9 80.6 76.2 66.2 72.7 73.9 Fourth Test Period. January 27 to February 5, 1915. Ten days. Barley and ground corn (1 to 1) 114 214 314 414 Average 82.1 80.5 80.0 79.6 80.6 89.5 88.2 88.1 88.4 88.6 18.2 17.8 20.6 8.5 16.3 69.9 65.5 65.5 63.5 66.1 65.3 72.1 49.8 59.5 61.7 Fifth Test Period. March 6 to 15, 1915. Ten days. Ground corn 114 214 314 414 Average 87.2 86.4 85.7 85.2 86.1 91.9 91.2 91.2 91.0 91.3 40.1 40.9 38.4 32.6 38.0 74.8 74.6 73.0 72.9 73.8 78.3 72.3 60.3 58.4 67.3 Sixth Test Period. March 16 to 25, 1915. Ten days. Ground corn 114 214 314 414 Average 86.2 87.7 85.4 85.3 86.2 91.6 92.0 91.6 91.3 91.6 38.2 45.0 40.0 35.0 39.6 72.8 77.5 73.2 73.2 74.2 64.9 75.6 57.2 52.0 62.4 'Not included in the average. 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OP PIGS 79 TABLE 13. Concluded Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Seventh Test Period. April 22 to May 1, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 84.1 91.3 48.6 72.5 73.5 214 87.2 93.1 59.4 76.2 76.2 314 85.2 91.7 50.7 75.4 69.2 414 85.2 91.2 51.1 74.4 79.3 Average 85.4 91.8 52.5 74.6 74.6 Eighth Test Period. May 2 to 11, 1915. Ten days. Tankage and ground corn (1 to 7.5) 114 86.5 93.5 50.9 74.2 82.0 214 87.1 93.0 60.0 76.1 84.0 314 83.0 89.9 45.7 72.4 70.7 414 83.6 90.4 45.3 73.0 71.2 Average 85.1 91.7 50.5 73.9 77.0 TABLE 14. SUMMARY OF THE AVERAGE COEFFICIENTS OF DIGESTIBILITY OF THE EATIONS Period Dry sub- stance Nitro- gen-free extract Crude fiber Crude protein Ether extract Ground barley 1 716 81 6 16 8 55 6 36 1 Ground barley 2 699 80.7 11.4 523 29 9 Average 70.8 81.2 14.1 540 33 Ground barley and ground corn 3 81.2 89.1 13.7 66.9 73.9 Ground barley and ground corn 4 80.6 88.6 16.3 66.1 61.7 Average 80.9 88.9 15.0 665 678 Ground corn 5 86 1 91.3 38.0 73 8 67 3 Ground corn 6 86.2 91.6 39.6 74 2 62 4 Average 86 2 91.5 38.8 74 64 9 Tankage and ground corn 7 85.4 91.8 52.5 74.6 74.6 Tankage and ground corn 8 85.1 91.7 50.5 73 9 77 Average. . 85.3 91.8 51.5 74.3 75.8 corn fed together in the ratio of 1 to 1 in Periods 3 and 4 varied for the different animals during the same period. This is especially true of the coefficients for the crude fiber, the ether extract, and the crude protein. The average coefficients of digestibility of the nutrients of this ration except the ether extract and the crude fiber agreed very closely for the two periods. The average coefficients of digestibility of the nutrients of the ration of ground barley and ground corn fed together in the ratio of 1 to 1 to each of the four pigs for the two ten-day periods (eight diges- 80 BULLETIN No. 200 [May, tion trials) were as follows: dry substance, 80.9; nitrogen-free ex- tract, 88.9 ; crude fiber, 15.0 ; crude protein, 66.5 ; and ether extract, 67.8. On comparing the average coefficients of the nutrients of the ration of ground barley and ground corn fed together in the ratio of 1 to 1 with those of the rations of ground barley and of ground corn when fed alone, it will be noted that the coefficients of the nutrients for the ration of barley and corn were in all cases, excepting those of the ether extract, intermediate between those of the barley fed alone and those of the corn fed alone. Tankage and Ground Corn (1 to 7.5). The coefficients of digesti- bility of the nutrients of this ration varied significantly for the differ- ent pigs during the same period. The average coefficients of all the nutrients of this ration agreed closely for the two experimental pe- riods. The average coefficients of digestibility of the nutrients of the ration of tankage and ground corn fed together in the ratio of 1 to 7.5 to each of the four pigs for the two ten-day periods (eight digestion trials) were as follows : dry substance, 85.3 ; nitrogen-free extract, 91.8 ; crude fiber, 51.5 ; crude protein, 74.3 ; and ether extract, 75.8. These results agree quite closely with the corresponding average results ob- tained in the eight digestion experiments with the same ration reported above in the first series of experiments. On comparing the average coefficients of the nutrients of this ration with those of the ration of ground barley when fed alone, it will be noted that all of the nutrients of the tankage and ground corn were digested much more thoroly than those of the barley. A comparison of the average coefficients of the nutrients of the ration of tankage and ground corn fed together with the ration of corn fed alone shows that the dry substance, the crude protein, and the nitro- gen-free extract of the tankage and corn were digested to practically the same extent as those of the ground corn alone, while the ether ex- tract and the crude fiber of the tankage and corn were digested much more thoroly than those of the ground corn alone. These findings are in accord with those obtained in the first series of experiments. THE INFLUENCE OF ONE FEED UPON THE DIGESTIBILITY OF THE NUTRIENTS OF ANOTHER FEED The data for the coefficients of digestibility of the nutrients of* barley, as determined directly when fed alone, and as calculated indi- rectly from the results of direct digestion experiments with the com- bined ration composed of barley and ground corn and the ground corn alone, are given in Table 15. It will be noted that the individual data and the average data for the four pigs show that the calculated values indirectly determined for the coefficients of digestibility of the dry substance, the nitrogen-free extract, the crude protein, and the ether 1917} DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 81 TABLE 15. COEFFICIENTS OF DIGESTIBILITY OF GROUND BARLEY, DIRECTLY AND INDIRECTLY DETERMINED Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Ground barley fed alone. First Test Period 114 73.5 81.9 20.9 60.4 64.9 214 71.9 81.1 14.0 57.4 27.2 314 69.8 80.4 15.5 51.6 28.2 414 71.3 82.9 5.9 53.0 24.1 Average 71.6 81.6 16.8 55.6 36.1 Ground barley calculated from the barley and corn ration. Third and Fifth Periods 114 77.3 86.0 10.0 66.1 84.5 214 75.5 85.6 -2.9 60.8 83.0 314 76.5 87.8 -13.9 61.0 76.4 414 77.9 88.3 3.9 56.3 76.0 Average 76.8 86.9 -0.7 61.1 80.0 Ground barley fed alone. Second Test Period 114 74.2 84.8 10.1 55.5 64.6 214 70.0 80.3 7.5 56.8 22.1 314 67.7 79.1 9.2 48.2 22.8 414 67.6 78.7 18.7 48.8 10.2 Average 69.9 80.7 11.4 52.3 29.9 Ground barley calculated from corn and barley ration. Fourth and Sixth Test Periods 114 78.3 87.4 9.9 67.4 66.0 214 73.7 84.4 6.5 55.3 66.1 314 74.9 84.6 12.6 59.1 37.0 414 74.3 85.4 -2.6 55.3 61.8 Average 75.3. . 85.5 6.6 59.3 57.7 extract of the barley are considerably higher than the corresponding coefficients of the barley determined directly by the digestion experi- ments. While the calculated results for the crude fiber are irregular, they nevertheless indicate that the calculated coefficients indirectly deter- mined for this nutrient of the barley are, on the whole, somewhat lower than the corresponding coefficients of the barley determined directly. The data for the coefficients of digestibility of the nutrients of the ground corn, as determined directly when fed alone, and as calculated indirectly from the direct experiments with the ration composed of barley and ground corn and the barley alone, are given in Table 16. A study of these data leads, in general, to the same conclusions as to the variations and differences between the direct and indirect coefficients of the nutrients of ground corn as were found in the case of the direct and indirect coefficients for barley. 82 BULLETIN No. 200 [May, The data for the coefficients of digestibility of the nutrients of the ration composed of one part of ground barley and one part of ground corn, as determined directly and as calculated indirectly, first, from the direct determinations for the barley and the corn rations, and second, from the indirect determinations for the barley and the corn rations are given in Table 17. It is apparent that the coefficients for the dry substance, the nitrogen-free extract, the crude protein, and the ether extract of the ration calculated from the coefficients for the ground barley and the ground corn, each determined directly, are considerably lower, while those for the crude fiber are considerably higher, than the corresponding coefficients directly determined for the mixed ration. These findings seem to prove that the dry substance, TABLE 16. COEFFICIENTS OF DIGESTIBILITY OF GROUND CORN, DIRECTLY AND INDIRECTLY DETERMINED Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Ground corn fed alone. Fifth Test Period 114 87.2 91.9 40.1 74.8 78.3 214 86.4 91.2 40.9 74.6 72.3 314 85.7 91.2 38.4 73.0 60.3 414 85.2 91.0 32.6 72.9 58.4 Average 86.1 91.3 38.0 73.8 67.3 Ground corn calculated from the barley and corn ration. First and Third Test Periods 114 91.2 96.0 13.9 81.6 89.5 214 90.2 95.7 0.2 78.7 58.2- 314 92.8 98.6 -32.5 84.2 88.0 414 92.2 96.4 30.5 76.9 56.4 Average 91.6 96.7 3.0 80.4 73.0 Ground corn fed alone. Sixth Test Period 114 86.2 91.6 38.2 72.8 64.9 214 87.7 92.0 45.0 77.5 75.6 314 85.4 91.6 40.0 73.2 57.2 414 85.3 91.3 35.0 73.2 52.0 Average 86.2 91.6 39.6 74.2 62.4 Ground corn calculated from the barley and corn ration. Second and Fourth Test Periods 114 90.5 94.3 37.7 86.9 65.7 214 91.6 96.1 42.5 75.7 44.7 314 93.0 97.2 48.3 86.1 65.4 414 92.4 98.0 -16.2 80.9 81.6 Average 91.9 96.4 28.1 82.4 64.4 1917} DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 83 TABLE 17. COEFFICIENTS OF DIGESTIBILITY OF A EATION OF GROUND BARLEY AND GROUND CORN (1 TO 1), DIRECTLY AND INDIRECTLY DETERMINED Pig Dry substance Nitrogen- free extract Crude fiber Crude protein Ether extract Ground barley and ground corn (1 to 1) fed together, direct determination. Third Test Period 114 214 314 414 Average 82.1 80.8 81.0 81.0 81.2 88.9 88.4 89.5 89.6 89.1 18.8 10.0 1.4 12.3 13.7 70.1 67.1 66.5 63.9 66.9 80.6 76.2 66.2 72.7 73.9 Ground barley and ground corn (1 to 1) calculated from the direct determinations of the barley ration and the corn ration. First and Fifth Test Periods 114 214 314 414 Average 80.2 79.0 77.5 78.1 78.7 86.9 86.1 85.8 86.9 86.4 26.5 21.9 22.2 13.7 21.1 67.0 65.3 61.4 62.1 64.0 73.4 55.9 48.6 45.9 56.0 Ground barley and ground corn (1 to 1) calculated from the indirect determina- tions for the barley ration and the corn ration (see second sections of Tables 15 and 16) 114 214 314 414 Average 87.1 82.7 84.4 84.9 84.0 91.0 90.6 93.2 92.3 91.8 11.1 -2.0 -19.3 11.0 0.2 73.2 69.0 71.6 65.7 69.9 87.7 91.0 83.8 98.7 90.3 Ground barley and ground corn (1 to 1) fed together, direct determination. Fourth Test Period 114 214 314 414 Average 82.1 80.5 80.0 79.6 80.6 89.5 88.2 88.1 88.4 88.6 18.2 17.8 20.6 8.5 16.3 69.9 65.5 65.5 63.5 66.1 65.3 72.1 49.8 59.5 61.7 Ground barley and ground corn (1 to 1) calculated from the direct determinations of the barley ration and the corn ration. Second and Sixth Test Periods 114 214 314 414 Average 80.0 78.6 76.3 76.2 77.8 88.2 86.1 85.3 85.0 86.2 18.3 18.5 18.2 23.5 19.6 63.4 66.3 59.6 60.0 62.3 64.8 56.1 44.7 42.1 51.9 Ground barley and ground corn (1 to 1) calculated from the indirect determination of the barley ration and the corn ration (see fourth sections of Tables 15 and 16) 114 214 314 414 Average 84.2 82.4 83.8 83.1 83.4 90.8 90.2 90.9 91.1 90.8 18.0 17.0 23.1 -6.5 12.9 76.3 64.7 71.4 67.0 69.9 65.8 87.1 55.0 76.6 71.1 84 BULLETIN No. 200 [May, the nitrogen-free extract, the crude protein, and the ether extract of the two feeds when fed together are more digestible than they are when fed alone, while the crude fiber is less digestible. On the other hand, it is evident from the data given in Table 17 that the coefficients for the dry substance, the nitrogen-free extract, the crude protein, and the ether extract of the ration calculated from the coefficients determined indirectly for the barley and the ground corn rations are considerably higher, while those of the crude fiber are considerably lower, than the corresponding coefficients directly determined for the mixed ration. It should be noted in this connection that the coefficients for the dry substance and the nitrogen-free extract for the wheat flour mid- dlings and the ground corn ration, calculated from the direct deter- minations of the middlings and the ground corn fed singly (see page 69), were considerably higher than those directly determined from the mixed ration. However, the coefficients for the dry substance and the nitrogen-free extract for the barley and ground corn ration, calculated from the direct determinations of the barley and ground corn fed singly (see page 83), were considerably lower than those directly determined from the mixed ration. Further, the co- efficients for the protein of the wheat flour middlings and the ground corn ration, calculated from the direct determinations of the mid- dlings and the ground corn fed singly, were not much different from those directly determined for the mixed ration. However the coeffi- cients for the protein of the barley and ground corn ration, calculated from the direct determinations of the barley and corn fed singly, were considerably lower than those directly determined from the mixed ration. It is therefore evident that, in some cases, one feed does not influ- ence the digestibility of the individual nutrients of another feed and, in other cases, it does influence the digestibility of the individual nutri- ents of the other feed in one of the two following ways: first, the nutrients of the feeds when fed as mixed feeds are more digestible than they are when each feed is used alone ; or, second, the nutrients of feeds when fed as mixed feeds are less digestible than they are when each feed is used alone. "With the limited data at present available relating to this subject, it is impossible to explain logically the above mentioned differences shown by different combinations of feeds upon the digestibility of their nutrients as compared with the digestibility of the nutrients of the individual feeds when fed alone. This subject is being further studied at this station. The results of these researches on the influence of one feed upon the digestibility of another feed demonstrate clearly, first, that the co- efficients of digestibility of feeds calculated indirectly by subtracting the weights of the digestible nutrients of one feed as directly deter- mined in other periods from the corresponding values for two feeds 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 85 combined may be, and probably often are, decidedly inaccurate ; and second, that the weights of the digestible nutrients of a mixed ration calculated by the use of the coefficients of digestibility of the nutrients obtained directly for the individual feeds when fed alone may be de- cidedly inaccurate. It therefore seems evident from these considerations that, in order to obtain accurate results for the coefficients of digestibility of mixed rations, digestion experiments should be made directly upon the mixed rations as fed. In other words, in the future, coefficients of digesti- bility of the nutrients for mixed rations should be obtained and re- ported, rather than merely those for the individual feeds composing the rations. INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGEST THEIR FEED The data for the coefficients of digestibility of the crude protein obtained in thirty- two digestion trials of ten days each, in which four rations were fed to each of four pigs, are given in Table 18. Examina- tion of the figures shows that the individual coefficients for Pig 214 are significantly greater than the individual coefficients for Pig 414, in each of the eight experiments. A similar comparison of the coeffi- cients of digestibility of protein for Pigs 214 and 314 demonstrates a similar significant difference. Since conditions thruout the experi- ment were practically identical, the pigs also being litter mates and having been fed together from birth, the data lead clearly to the con- clusion that the distinct and well-defined differences between the co- efficients of digestibility of crude protein for Pig 214 and Pigs 314 and 414 thruout the eight experiments must have been due to individuality. A further study of the data of this table shows that there is a con- siderable difference between the coefficients of digestibility of crude protein for Pigs 114 and 314 and for Pigs 114 and 414 that apparently can be assigned to the factor of individuality. However, there are practically no differences in the coefficients of digestibility of crude protein for Pigs 114 and 214, or for Pigs 314 and 414, that can be assigned to the factor of individuality. Examination of the results presented in Table 18 for the coeffi- cients of digestibility of the ether extract of the four rations shows that there were marked and well-defined differences due apparently to the individuality of the pigs. Inspection of the data given in Table 18 for the coefficients of the dry matter and the nitrogen-free extract, shows that there was a tendency toward individual differences especially in the average results. However, the individuality of these pigs with reference to their power of digesting dry matter and nitrogen-free extract is not so clearly evident as it is in the case of crude protein and ether extract. 86 BULLETIN No. 200 [May, TABLE 18. SUMMARY OF THE COEFFICIENTS OF DIGESTIBILITY OF THE NUTRIENTS SHOWING THE INDIVIDUALITY OF PIGS AS TO THE THORONESS WITH WHICH THEY DIGESTED THEIR FEED Period Eation Pig 214 Pig 114 Pig 314 Pig 414 Pig 214 Pig 114 Pig 314 Pig 414 Crude protein Ether extract 1 2 3 4 5 6 7 8 Barley (alone) . . . Barley (alone) . . . Barley and corn (Itol). . 57.4 56.8 67.1 65.5 74.6 77.5 76.2 76.1 68.9 60.4 55.5 70.1 69.9 74.8 72.8 72.5 74.2 68.8 51.6 48.2 66.5 65.5 73.0 73.2 75.4 72.4 65.7 53.0 48.8 63.9 63.5 72.9 73.2 74.4 73.0 65.3 64.9 64.6 80.6 65.3 78.3 64.9 73.5 82.0 71.8 27.2 22.1 76.2 72.1 72.3 75.6 76.2 84.0 63.2 24.1 10.2 72.7 59.5 58.4 52.0 79.3 71.2 53.4 28.2 22.8 66.2 49.8 60.3 57.2 69.2 70.7 53.1 Barley and corn (Ito 1) Ground corn (alone) Ground corn (alone) Tankage and corn (Ito 7.5) Tankage and corn (Ito 7.5) Averasre. . Dry substance Nitrogen-free extract 1 2 3 Barley (alone) . . . Barley (alone) . . . Barley and corn (Ito 1). . 73.5 74.2 1 82.1 71.9 70.0 80.8 71.3 67.6 81.0 69.8 67.7 81.0 81.9 84.8 889 81.1 80.3 884 82.9 78.7 89 6 80.4 79.1 895 4 Barley and corn (Itol). . 82.1 80.5 79.6 80.0 89 5 88 2 884 88.1 5 Ground corn (alone) 87.2 86.4 85.2 85.7 91.9 91.2 91.0 91 2 6 Ground corn (alone) , 86 2 87.7 85 3 85 4 91 6 92 91 3 91 6 7 Tankage and corn (Ito 7.5) 84.1 87.2 85.2 '85.2 91.3 93.1 91.2 91.7 8 Tankage and corn (Ito 7.5) 865 87.1 83 6 83 93 5 93 904 899 Averaere. . 81.9 81.5 79.9 79.5 89.2 88.4 87.9 87.7 The results of this second series of experiments show greater dif- ferences in the coefficients of digestibility of the nutrients of the same feeds by different animals than did those of the first series. For ex- ample, the average coefficient of digestibility of the protein in the eight tests for Pig 214 was 5.5 percent greater than that for Pig 414. Again, the average coefficient of digestibility of the ether extract in the eight tests for Pig 114 was 35.2 percent greater than that for Pig 414. The total gain in live weight of Pig 114 for the 80 days was 26.3 percent greater than that for Pig 414. The results of this second series of experiments support those ob- tained in the first series of experiments in demonstrating that the co- efficients of digestibility of the nutrients of a number of different ra- tions show constantly higher values for some pigs than for others. The total gains in weight of each of the four pigs used in this experiment during the eight experimental periods, each of ten days' 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 87 duration during which time each of the four animals received the same kind of feeds and approximately the same quantity of feeds per 100 pounds of live weight, were as follows: Pig 114, 62.5 pounds; Pig 214, 57.0 pounds; Pig 314, 54.5 pounds; and Pig 414, 49.5 pounds. The average live weights of the pigs during the eight experimental periods were as follows : Pig 114, 277.5 pounds ; Pig 214, 229.8 pounds ; Pig 314, 218.3 pounds; and Pig 414, 200.5 pounds. The weights of the total feeds consumed during this same time were as follows : Pig 114, 459.2 pounds ; Pig 214, 376.8 pounds ; Pig 314, 364.0 pounds ; and Pig 414, 335.6 pounds. The weights of feed required to produce 100 pounds of gain during the ten experimental periods were as follows : Pig 114, 735 pounds; Pig 214, 661 pounds; Pig 314, 668 pounds; and Pig 414, 678 pounds. Comparing these gains in live weight and the economy of gains in weight with the average coefficients of digestibility of the nutrients of the feeds for each animal, it will be observed that there is possibly a better correlation between the coefficients of digestibility and the gains or the economy of the gains in weight in this second series of experi- ments than there was in the first series. For example Pig 214, which on the average digested all of the nutrients of the feeds somewhat more thoroly than Pigs 314 and 414, altho weighing on an average 277.5 pounds, made a gain of 57 pounds and required only 661 pounds of feed to produce 100 pounds of gain ; while Pigs 314 and 414, weighing only 218.3 and 200.5 pounds, respectively, made gains of 54.5 and 49.5 pounds, respectively, and required 668 and 678 pounds of feed, respectively, to produce 100 pounds of gain. These results would seem to indicate that Pig 214 possibly made more economical gains than Pigs 314 and 414. Further, Pig 314, which on the average digested all of the nutrients of the feeds only very slightly more thoroly than Pig 414, altho weighing somewhat more than that pig, yet possibly made slightly the more economical gains of the two. On the other hand, Pig 114, which on the average digested all of the nutrients of the feeds almost as thoroly as Pig 214, altho weighing 47.7 pounds more than Pig 214, gained 62.5 pounds but required 735 pounds of feed to pro- duce 100 pounds of gain, while Pig 214 gained 57 pounds and required only 661 pounds of feed to produce 100 pounds of gain. However, the difference between these two pigs as to economy of gains may be due, in large part at least, to the difference in their live weights. 88 BULLETIN No. 200 [May.. SUMMARY OF DATA OF BOTH SERIES OF EXPERIMENTS 1. Dry Substance. The order of the rations according to decreas- ing coefficients of digestibility of their dry substance was as follows: ground corn, 87.1 ; tankage and ground corn, 86.0 ; ground barley and ground corn, 80.9; wheat flour middlings and ground corn, 79.1; wheat flour middlings, 74.4 ; and ground barley, 70.8. 2. Nitrogen-free Extract. The order of the rations according to decreasing coefficients of digestibility of their nitrogen-free extract was as follows: tankage and ground corn, 92.2; ground corn, 92.1; ground barley and ground corn, 88.9; wheat flour middlings and ground corn, 85.9; wheat flour middlings, 81.2; and ground barley, 81.2. 3. Crude Fiber. The order of the rations according to decreasing coefficients of digestibility of their crude fiber was as follows: tankage and ground corn, 51.2 ; ground corn, 34.8 ; wheat flour middlings, 21.0 ; ground barley and ground corn, 15.0 ; ground barley, 14.1 ; and wheat flour middlings and ground corn, 12.1. 4. Crude Protein. The order of the rations according to decreas- ing coefficients of digestibility of their crude protein was as follows: wheat flour middlings, 80.0 ; wheat flour middlings and ground corn, 77.3 ; tankage and ground corn, 74.8.; ground corn, 74.5 ; ground bar- ley and ground corn, 66.5 ; and ground barley, 54.0. 5. Ether Extract. The order of the rations according to decreas- ing coefficients of digestibility of the ether extract was as follows: wheat flour middlings, 85.4 ; wheat flour middlings and ground corn, 83.4 ; tankage and ground corn, 80.8 ; ground corn, 68.3 ; ground bar- ley and ground corn, 67.8; and ground barley, 33.0. 6. Average Coefficients of Digestibility of the Rations. The fol- lowing is a summary of the average coefficients of the rations fed in these experiments : Ration No. of ex- peri- ments Dry sub- stance Nitro- gen- free ex- tract Crude fiber Crude pro- tein Ether ex- tract Wheat flour middlings 16 74.4 81.2 21.0 80.0 85.4 16 87.1 92.1 34.8 74.5 68.3 Ground barley 8 70.8 81.2 14.1 54.0 33.0 Wheat flour middlings and ground corn (1 to 1) . . 8 79.1 85.9 12.1 77.3 83.4 Ground barley and ground corn (1 to 1) Tankage and ground corn (1 to 7.5) .... 8 16 80.9 86.0 88.9 92.2 15.0 51.2 66.5 74.8 67.8 80.8 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 89 7. Influence of One Feed upon the Digestibility of the Nutrients of Another Feed. The following is a summary of the average results which show the influence of one feed upon the digestibility of another feed: Ration No. of ex- peri- ments Dry sub- stance Nitro- gen- free ex- tract Crude fiber Crude pro- tein Ether ex- tract Middlings direct 8 74.7 82.2 22.8 79.3 82.3 Middlings indirect 8 70.7 77.2 6.1 78.3 89.3 Corn direct 8 87.8 92.7 30.8 75.1 71.7 Corn indirect 8 83.7 88.9 -2.2 73.0 81.3 Barley direct 8 70 8 81.2 14.1 540 33.0 Barley indirect 8 76 1 862 3.7 60.2 68.9 Corn direct 8 862 91.5 38.8 74.0 o4.9 Corn indirect 8 91.8 96.6 15.6 81.4 68.7 Middlings and corn direct 8 79.1 86.0 12.1 77.3 83.5 Middlings and corn indirect 1 8 81.1 88.1 24.8 78.0 78.8 Middlings and corn indirect 2 8 77.1 83.8 -0.7 76.6 88.1 Barley and corn direct 8 80.9 88.9 15.0 66.5 67.8 Barley and corn indirect 1 8 78.3 86.3 20.4 63.2 54.0 Barley and corn indirect 2 . . 8 83.7 91.3 6.6 69.9 80.7 'Calculated from the direct determinations of the coefficients of the individual feeds. 'Calculated from the indirect determinations of the coefficients of the individual feeds. 8. Individuality of Pigs as to the Thoroness With Which They Digest Their Feeds. Summaries of the nutrients of the feeds showing the individuality of pigs as to the thoroness with which they digest their feeds are given on pages 72 and 87 of this bulletin. CONCLUSIONS 1. The weights of the feces of pigs, per pound of feed,, vary mark- edly depending upon the character of the ration. Such differences in the weights of the feces per pound of feed are due, in large part at least-, to variations in the water content of the feces and to variations in the coefficients of digestibility of the dry substance of the rations. 2. The results obtained in these experiments clearly indicate that in some cases one feed does not influence the digestibility of the indi- vidual nutrients of another feed with which it is fed, and in other cases that it does influence the digestibility of the individual nutrients of the other feed in one of the two following ways : first, the nutrients of the feeds when fed as mixed feeds are more digestible than they are when each feed is used alone; or, second, the nutrients of the feeds when fed as mixed feeds are less digestible than they are when each feed is used alone. With the limited data at present available relating 90 BULLETIN No. 200 [May, to this subject, it is impossible to explain logically these differences shown by different combinations of feeds, when fed together, upon the digestibility of their combined nutrients as compared with the digesti- bility of the nutrients of the individual feeds when fed alone. 3. The results of these researches on the influence of one feed upon the digestibility of another feed demonstrate clearly : first, that the coefficients of digestibility of the nutrients of feeds calculated indi- rectly by subtracting the weights of the digestible nutrients of one feed as directly determined in other tests from the corresponding values for the two feeds combined, may be, and probably often are, decidedly inaccurate ; and second, that the weights of the digestible nutrients of a mixed ration, calculated by the use of the coefficients of digestibility of the nutrients obtained directly for the individual feeds when fed alone, may be decidedly inaccurate. 4. It therefore apparently follows that in order to obtain strictly accurate results for the coefficients of digestibility of mixed rations, digestion experiments should be made directly upon the mixed rations as fed. In other words, in the future coefficients of apparent digesti- bility of the nutrients for mixed rations should be obtained and re- ported, rather than those for individual feeds composing the rations. 5. The results of these experiments demonstrate clearly that dif- ferent animals of the same species may show individuality as to the thoroness with which they digest the nutrients of their feeds. In other words, under conditions that are practically identical thruout the same experiment, the coefficients of digestibility of the nutrients of a num- ber of different rations show significantly higher values for some pigs than for others. However, the differences in the coefficients of digesti- bility of the nutrients of the same feeds by the different pigs are prob- ably too small to be considered of much, if any, practical or economic importance. The authors wish to acknowledge the efficient assistance rendered by W. F. Campbell in the feeding, weighing, and care of the animals. 1917} DIGESTIBILITY OF MIXED FEEDS ; INDIVIDUALITY OP PIGS 91 X < lU _ I . 92 BULLETIN No. 200 [May, 50TTOM VIE-W 1 1 k i-n IF- , \ i -.ClALVA/YIZED 18,0/M \ ~ X ' C VIEW SIDE: View /VOTE-;- J-HE DOTTED LIAIES SHOW THE CVE.VATVB.Er Of THE fALSE BOTTOAA. 1917] DIGESTIBILITY OF MIXED FEEDS; INDIVIDUALITY OF PIGS 94 BULLETIN No. 200 UNIVERSITY OF ILLINOIS-URBANA