I/I B R.ARY OF THE UNIVERSITY OF ILLINOIS' 630.7 UGb COp AGRICULTURE NOTICE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Thett, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN mi 2 9 L161 O-1096 UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 291 A TECHNICAL STUDY OF THE DIGEST- IBILITY OF CORN STOVER SILAGE FOR BEEF COWS BY T. S. HAMILTON AND H. P. RUSK URBANA, ILLINOIS, MAY, 1927 THE more practical aspects of this investigation, which included a study of the digestibility of corn stover silage for beef cows and also a de- termination of the metabolizable energy of the silage, are as follows: 1. Apparently no considerable change in chemical composition is brought about by ensiling corn stover. 2. The availability to ruminants of the nutrients in corn stover silage is practically the same as that of the nutrients in ordinary corn stover. 3. There is about 85 percent as much total digesti- ble nutrients in stover silage as there is in the same weight of whole corn silage; however, experimental feeding trials at this Station indicate that in practical feeding stover silage is only about two-thirds as valu- able as normal silage. 4. The advantages of feeding stover silage over ordinary stover from the shock or pasturing in the fields are (1) reduction of loss of material from ex- posure to rain and wind; (2) no loss from tramping; (3) an increased palatability, causing a greater con- sumption and smaller waste in feeding due to the fact that stalks have been softened, broken up, made juicy and palatable; (4) a much greater ultimate utilization of the nutrients of the corn crop than when the stover is fed from the shock or is pastured in the field. 5. The ensiling of stover offers a method of util- izing the by-products of corn culture in an effective and economical way without limiting the utilization of the main product, the grain. A TECHNICAL STUDY OF THE DIGEST- IBILITY OF CORN STOVER SILAGE FOR BEEF COWS By T. S. HAMILTON, Associate in Animal Nutrition, and H. P. RUSK, Chief of Cattle Husbandry Under methods of harvesting prevalent thruout much of the corn belt the stalk, leaves, and husks of the corn plant are left in the fields. The utilization of the potential feeding value of this by-product has long been a subject for study and experimentation. Pasturing in the fields is obviously wasteful and often damages the soil by causing it to puddle. Shredded stover and ordinary stover from shocked corn fail to meet the requirements fully, because large portions are woody and unpalatable, and consequently are wasted. The production of normal corn silage from the entire corn plant probably makes possible the most complete and effective utilization. However, a demand for a method which does not limit the disposal of the grain has stimulated a revival of interest in the possibilities of silage made from the stover without the grain. Results of recent ex- perimental feeding trials lend some encouragement for this method of utilizing the stover. These results, together with the fact that analyti- cal studies indicate that so far as the chemical constituents are con- cerned the stover contains nearly one-half of the total crude protein, carbohydrates, and fat of the entire corn plant, have led to many ex- travagant claims regarding the nutritive value of stover silage. The nutritive value of a feed, however, depends not only upon its chemical composition, but also upon the ability of a given class of an- imals to utilize the various nutrients in the combinations found in that feed. The object of this investigation, therefore, was to make possible a better understanding of the true feeding value of corn stover silage by determining not only the apparent digestibility of the nutrients, but also the metabolizable energy (energy of the feed consumed minus the energy of the solid, liquid, and gaseous excreta) of this product when fed to beef cows. PLAN OF INVESTIGATION The investigation was carried out during the months of January and February, 1923. The digestion stalls were located in a building which was kept fairly cool, but not cold. The experimental animals were dry, pregnant cows of beef type weighing about 1,200 pounds. These cows were taken from a group that was being wintered on a ra- tion of stover silage and soybean oil meal, and consequently were ac- customed to the experimental ration. Eight animals were used, four 467 468 BULLETIN No. 291 [May, in each of two 15-day digestion trials. Each digestion trial consisted of a 7-day preliminary feeding period, during which the cows were fed individually the same rations which they were to receive later during the collection period, and a period in the digestion stalls of 8 days, during the last 7 days of which the collections were made. Collections were made by attendants constantly on duty, two at a time. The feces were collected in especially constructed shovels and placed immediately in air-tight containers. The urine was collected in galvanized iron buckets made to fasten on the ends of wooden handles about 5 feet long. The urine was poured into air-tight containers immediately after collection. In order to guard against accidents in making the collections, a large shallow water-tight galvanized iron pan about 4 feet long, 3 feet wide, and 6 inches deep was placed behind each cow. Each stall was equipped with a heavy canvas pad about 3 inches thick so that the cow did not stand on the board floor of the stall. The stalls were wide enough so that the cows could lie down at will. The ration consisted of a good grade of corn stover silage, soybean oil meal, salt, and water. The silage used during both trials was from the same silo, altho that used during the second trial was taken from a lower level. The silage was made from the stover of shock corn which had been cut and shocked at the usual time. After the ears had dried sufficiently for cribbing, the shocks were hauled to the silo, the ears removed, and the stover cut and blown into the silo, water being added thru the distributor at the rate of approximately 100 pounds per 100 pounds of stover. The same shipment of soybean oil meal served thruout both trials. Each cow was fed all the silage she would eat. During the diges- tion trials this averaged nearly 50 pounds of fresh silage daily. 1 The daily allowance of soybean oil meal was 1 pound per cow. The cows were fed twice daily: in the morning (just after the feces and urine had been aliquoted), and in the evening. Half the daily ration was given at each feeding. The soybean oil meal was sprinkled over the silage. After the first 5 days of the first trial 1 ounce of salt was regularly added to the morning feed. Water was offered from a pail twice daily, once before the morning feed and again before the evening feed. METHOD OF SAMPLING The urine and feces were aliquoted daily, about 8:30 o'clock each morning. Each day's excretion of urine and feces from each cow was 'During the entire winter the average daily consumption of the lot of ten cows from which the group was taken was 66.53 pounds of stover silage and 1 pound of soybean oil meal. 1927] CORN STOVER SILAGE FOR BEEF Cows 469 separately weighed, mixed, and aliquoted. The aliquots taken thruout the tests were one-tenth the daily excretion. The urine was mixed by shaking and stirring, while the feces were mixed and quartered down in a large shallow pan with the aid of a bricklayer's hand trowel. The feces were of such consistency that this method of mixing proved very satisfactory. The aliquoting was done in a cool room and as quickly as possible so that the loss in moisture during this procedure was cer- tainly very small. The daily aliquots from each animal were placed in air-tight containers and kept at about freezing temperature. Each succeeding daily aliquot was added to the preceding one until the end of the collection period, when they were carefully composited and an- alyzed. The feces were analyzed in the fresh condition. The orts re- maining in the manger each morning were weighed and immediately air-dried. The silage was taken from the silo each morning and brought to the digestion room in large canvas bags in time for the morning feed- ing. It was then mixed and the daily ration was weighed out. The evening allowance was placed in 50-pound lard cans which were tightly covered. While the silage was being weighed out for the day's feed, an occasional handful was placed in a pail for analysis. Exactly 1 kilo- gram of silage was taken in this manner each morning for analysis. This sample was taken immediately to the laboratory in a tightly cov- ered pail and quickly air-dried at about 65 C. The daily air-dried samples were combined to form a composite sample for the collection period. The orts from each animal were treated in exactly the same manner. Only one sample of soybean oil meal was analyzed, and this was taken by placing a handful of the meal in a pail each morning at the time the feed was being weighed out. RESULTS OF EXPERIMENTS The average weight of the four cows in the first trial was 1,255 pounds at the beginning of the preliminary period, 1,250 pounds at the beginning of the collection period, 1,194 pounds at the end of the trial, and 1,279 pounds two weeks later; thus, the average loss in weight while in the stalls was 56 pounds (Table A, Appendix) . The same data for the four cows in the second trial are 1,141 pounds at the start, 1,109 when placed in the digestion stalls, and 1,084 at the end of the trial, the average loss in weight being 25 pounds. One week after their re- turn to the feed lot these cows averaged 1,145 pounds in weight. The nitrogen balance data (Table D of the Appendix) indicate that there was some loss in body flesh, tho, because of the immediate return of each cow to her original weight within one or two weeks after termi- 470 BULLETIN No. 291 nation of the experiment, 1 most of the loss in weight was certainly loss in fill. The percentage composition of the soybean oil meal and of the corn stover silage used during the two collection periods is given in Table 1. The silage used during the first period was taken from the TABLE 1. PERCENTAGE COMPOSITION AND GROSS ENERGY OF FEEDS Gross Feed Crude N-free Crude Ether Crude energy protein extract fiber extract ash per 100 pounds therms Corn stover silage, Period I 28.41 1.81 14.13 9.38 .53 2.56 54.9 Corn stover silage, Period II 25.03 1.65 12.65 8.02 .50 2.21 48.4 Soybean oil meal 90.63 39.95 36.18 6.73 5.07 6.59 197.8 TABLE 2. PERCENTAGE COMPOSITION AND GROSS ENERGY OF ORTS, FECES, AND URINE Cow No. Sample Dry sub- tance Crude protein* N-free extract Crude fiber Ether extract Crude ash Gross energy per 100 pounds Period I 1 Orts .... 28.84 1.25 12.34 9.41 .39 1.45 therms 50.5 o 1 Feces . . . Urine. . . 16.35 1.62 (.73) 7.14 4.00 .24 3.35 32.1 8.3 2 Orts Feces . . . 26.61 13.27 1.67 1.21 ( 74) 13.40 6.67 9.10 3.06 .43 .21 2.01 2.12 52.3 25.5 6 8 3 Orts Feces. . . 28.67 13.82 1.89 1.44 ( 78) 14.26 5.94 9.76 3.16 .51 .23 2.25 3.05 56.4 28.3 8.6 4 Orts Feces . . . Urine. . . 24.29 15.38 1.55 1.40 (.81) 12.24 6.66 8.24 3.78 .39 .29 1.87 3.25 48.0 29.9 8.6 Period II 5 Orts 34.36 2.30 18.04 10.86 .65 2.51 65.6 Feces . . . Urine . . . 14.76 1.40 (.60) 7.46 3.52 .25 2.13 26.4 7.6 6 Orts Feces . . . Urine . . . 27.23 12.92 1.44 1.23 (.75) 13.31 6.28 10.29 3.17 .35 .28 1.84 1.96 53.0 23.0 7.8 7 Orts Feces . . . 25.41 15.43 1.72 1.35 ( 69) 12.74 7.64 8.55 3.71 .47 .36 1.93 2.37 49.4 28.8 10.0 8 Orts Feces . . . Urine . . . 35.09 13.81 1.80 1.27 (.74) 16.55 6.87 14.22 3.29 .41 .24 2.11 2.14 69.2 25.4 7.6 In case of urine samples the figures in this column represent the percentage of total nitrogen instead of crude protein. *The lot of ten cows from which these eight test cows were taken averaged 1,055.5 pounds when started on this ration, November 1, 1922, and 1,159 pounds at the end of the winter trial, March 21, 1923. The average total gain per head was 103.5 pounds, or an average daily gain of .742 pound, for the 139.5 days, including time spent in the digestion trials. CORN STOVER SILAGE FOR BEEF Cows 471 upper part of the silo, and that used during the second period was taken from a lower level in the silo. The percentage composition of the orts, the fresh feces, and the urine is given in Table 2. In addition to the regular routine chemical determinations, the gross energy of all samples was regularly deter- mined in a bomb calorimeter. TABLE 3. AMOUNTS OF FEED OFFERED AND WATER CONSUMED, AND WEIGHT OF ORTS, FECES, AND URINE Cow No. Feed offered Water consumed Orts Feces Urine Stover silage Soybean meal Salt Period I 1... Ibs. 350 Ibs. 7 oz. 2 Ibs. 146.87 /6s. 4.04 Ibs. 261.49 Ibs. 107.27 2 320 7 2 228.56 24.32 301.79 132.78 3 300 7 2 191.94 53.98 238.28 82.15 4 320 7 2 139.81 19.55 236.39 102.83 Period II 5... 350 7 7 172.87 3.09 285.99 100.77 6... 350 7 7 208 75 4.42 334.07 97.42 7 350 7 7 113.56 25.03 237.25 100.90 8.. .. .. 350 7 7 172.25 1.20 289.97 116.80 The total weights of feed offered, water consumed, orts left, and feces and urine excreted during the two 7-day collection periods are given in Table 3. DIGESTIBILITY OF CORN STOVER SILAGE All the data relative to the calculation of the coefficients of diges- tibility of the nutrients in the combined ration of corn stover silage and soybean oil meal, when fed in the ratio of approximately 1 to 50, are given in Table 4. The calculations were made in the usual manner and the table is self-explanatory. The calculations of the coefficients of digestibility of the nutrients in the corn stover silage alone are presented in Table 5. The correc- tion for the soybean oil meal in the ration was made in the usual man- ner, using coefficients of digestibility for soybean oil meal obtained at this Station on sheep. 1 The nutrients in the orts are assumed to be de- rived entirely from the corn stover silage. Therefore the nutrients con- sumed from the silage are calculated by subtracting the nutrients in the orts from the corresponding nutrients in the silage fed. The above as- sumption is made because of the small quantity of soybean oil meal in the ration, and because the orts remaining in the manger were usually Unpublished data from an experiment on the digestibility of soybean pro- ducts with sheep at the University of Illinois. 472 BULLETIN No. 291 [May, TABLE 4A. DIGESTIBILITY OF THE COMBINED RATION OP CORN STOVER SILAGE AND SOYBEAN OIL MEAL: PERIOD I (Amounts in pounds) Dry substance Crude protein N-free extract Crude fiber Ether extract Cow No. 1 Silage fed, 350 pounds 99.4 6.3 49.4 32.8 1.8 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 105.7 9.1 51.9 33.3 2.2 Orts, 4.04 pounds 1.0 .1 .5 .4 .0 104.7 9.0 51.4 32 9 2 2 Feces, 261.49 pounds 42.7 4.2 18.7 10.5 .6 Nutrients digested 62.0 4.8 32.7 22 4 1.5 Percentage digested (59.2) (53.3) (63.6) (68.1) (68.2) Cow No. 2 Silage fed, 320.0 pounds 90.9 5.8 45.2 30 1 7 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 97.2 8 6 47.7 30 5 2.1 Orts, 24.32 pounds 6.5 .4 3.3 2.2 .1 Nutrients consumed 90.7 8.2 44.4 28 3 2.0 Feces, 301.79 pounds 40.0 3.6 20.1 9.2 .6 Nutrients digested 50.7 4.6 24.3 19 1 1.4 (55 9) (56 1) (54.7) (67 5) (70 0) Cow No. 3 Silage fed 300 pounds 85 2 5 4 42 4 28 1 1 6 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 91.5 8.2 44.9 28 6 2.0 Orts, 53.98 pounds 15.5 1.0 7.7 5.3 .3 Nutrients consumed 76.0 7.2 37.2 23 3 1.7 Feces, 238.28 pounds 32.9 3.4 14.2 7.5 .6 Nutrients digested 43.1 3.8 23.0 15.8 1.1 Percentage digested (56.7) (52.8) (61.8) (67.8) (64.7) Cow No. 4 Silage fed, 320 pounds 90 9 5.8 45 2 30 1.7 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 97.2 8.6 47.7 30.5 2.1 Orts, 19.55 pounds 4.7 .3 2.4 1.6 .1 Nutrients consumed 92.5 8.3 45.3 28.9 2.0 Feces, 236.39 pounds 36.4 3.3 15.7 8.9 .7 Nutrients digested 56 1 5 29 6 20 1.3 Percentage digested (60.6) (60.2) (65.4) (69.2) (65.0) the larger, most unpalatable pieces of the stalk with no visible quan- tity of oil meal. The coefficients of digestibility of the soybean oil meal, taken from the average figures obtained on twelve sheep, are as follows: dry substance, 98 percent; crude protein, 88 percent; N-free extract, 100 percent; ether extract, 95 percent; and crude fiber, 60 per- cent. A summary of the coefficients of digestibility of the nutrients in the combined ration calculated in Table 4 is given in Table 6, while Table 7 gives the summary of the coefficients of digestibility of the corn stover silage alone as calculated in Table 5. A noticeable effect of the correction for the soybean oil meal is in the lowering. of the apparent digestibility of the crude protein of the combined rations from an average percentage of 55.6 to 39. Also, the digestibility of the ether extract was lowered from an average of 65.7 percent for the combined ration to an average of 59.2 percent for the silage alone. The total amount of ether extract in the silage, how- 1927] CORN STOVER SILAGE FOR BEEF Cows 473 TABLE 4B. DIGESTIBILITY OF THE COMBINED RATION OF CORN STOVER SILAGE AND SOYBEAN OIL MEAL: PERIOD II (Amounts in pounds) Dry substance Crude protein N-free extract Crude fiber Ether extract Cow No. 6 Silage fed, 350 pounds 87 6 5.8 44.3 28.1 1.8 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 93 9 8 6 46 8 28 6 2 2 Orts, 3.09 pounds 1.1 .1 .5 .3 .0 Nutrients consumed 92 8 8 5 46 3 28 3 2.2 Feces, 285.99 pounds 42.2 4.0 21.3 10.1 .7 Nutrients digested 50 6 4.5 25.0 18.2 1.5 Percentage digested (54.5) (52.9) (54.0) (64.3) (68.2) Cow No. 6 Silage fed, 350 pounds 87 6 5 8 44.3 28.1 1.8 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 93 9 8.6 46.8 28.6 2.2 Orts, 4.42 pounds 1.2 .1 .6 .4 .0 Nutrients consumed 92.7 8.5 46.2 28.2 2.2 Feces, 334.07 pounds 43.2 4.1 21.0 10.6 .9 49 5 4 4 25 2 17.6 1.3 (53 4) (51.8) (54.5) (62.4) (59.1) Cow No. 7 Silage fed, 350 pounds 87.6 5.8 44.3 28.1 1.8 Soybean oil meal fed, 7 pounds 6.3 2.8 2.5 .5 .4 Total ration 93.9 8.6 46.8 28.6 2.2 Orts, 25.03 pounds 6.4 .4 3.2 2.1 .1 87.5 8.2 43.6 26.5 2.1 Feces, 237.25 pounds 36.6 3.2 18.1 8.8 .8 50.9 5.0 25.5 17.7 1.3 Percentage digested (58.2) (61.0) (58.5") (66.8) (61.9) Cow No. 8 Silage fed, 350 pounds 87.6 5.8 44.3 28.1 1.8 Soybean oil meal fed, 7 pounds 2.8 2.5 .5 .4 Total ration 93.9 ~O 46.8 28.6 2.2 Orts, 1.20 pounds .4 .0 .2 .2 .0 Nutrients consumed Feces, 289.97 pounds 93.5 40.0 8.6 3.7 46.6 19.9 28.4 9.4 2.2 .7 Nutrients digested 53.5 4.9 26.7 18.9 1.5 Percentage digested (57.2) (57.0) (57.2) (66.5) (68.2) ever, is so small in comparison with the other nutrients that this ap- parent decrease in digestibility of ether extract need not be considered. The other nutrients are little affected. The average percentages of digestible nutrients in the corn stover silage are tabulated in Table 8. PREVIOUS INVESTIGATIONS INDICATE BETTER UTILIZATION OF CORN ROUGHAGES BY CATTLE THAN BY SHEEP The digestibility of corn stover silage has been determined by Tangl and Weiser. 1 Using wethers as experimental animals, these in- vestigators determined, in duplicate, the digestibility of stover silage taken at three different levels from a reinforced concrete, silo. A com- parison of the average digestion coefficients obtained by Tangl and Weiser, and those obtained in this investigation, is given in Table 9. This comparison shows a fairly close agreement between the values obtained in the two investigations, in all the nutrients except crude 474 BULLETIN No. 291 [May, TABLE 5. CALCULATION OF DIGESTIBILITY OF CORN STOVER SILAGE (Amounts in pounds) Dry substance Crude protein N-free extract Crude fiber Ether extract Period I Cow No. 1. 98.4 6 3 48 9 32 4 1 8 Nutrients digested Total 62.0 4.8 32.7 22.4 1.5 6.2 2.5 2 5 3 .3 Silage 55.8 2.3 30.2 22 1 1.2 Coefficient of digestibility for silage .... Cow No. 2 (57) 84.4 (37) 5 4 (62) 41.9 (68) 27 8 (67) 1.6 Nutrients digested Total 50.7 4.6 24.3 19.1 1.3 6.2 2.5 2 5 3 .3 Silage 44.5 2.1 21.8 18 8 1.0 Coefficient of digestibility for silage .... Cow No. 3 Nutrients consumed, silage (53) 69.7 (39) 4 4 (52) 34 7 (68) 22 8 (63) 1.3 Nutrients digested Total 43 1 3 8 23 15 8 1 1 Soybean oil meal 6 2 2 5 2 5 3 .3 Silage 36.9 1.3 20.5 15.5 .8 Coefficient of digestibility for silage .... Cow No. 4 Nutrients consumed, silage (53) 86 2 (30) 5 5 (59) 42 8 (68) 28 4 (61) 1.6 Nutrients digested Total 56.1 5.0 29.6 20.0 1.3 Soybean oil meal 6.2 2.5 2.5 .3 .3 Silage 49.9 2.5 27 1 19 7 1.0 Coefficient of digestibility for silage. . . . (58) (45) (63) (69) (63) Period II Cow No. 5 Nutrients consumed, silage 86 5 5 7 43.8 27 8 1 7 Nutrients digested Total 50 6 4 5 25 18 2 1 4 Soybean oil meal 6.2 2 5 2.5 3 .3 Silage 44 4 2 22 5 17 9 1 i Coefficient of digestibility for silage .... Cow No. 6 Nutrients consumed, silage (51) 86.4 (35) 5 7 (51) 43.7 (64) 27.7 (65) 1 7 Nutrients digested Total 49 5 4 4 25.2 17.6 1 1 Soybean oil meal 6.2 2.5 2.5 .3 .3 Silage 43 3 1 9 22 7 17 3 8 Coefficient of digestibility for silage .... Cow No. 7 Nutrients consumed, silage (50) 81.2 (33) 5 4 (52) 41.1 (62) 26 (47) 1.6 Nutrients digested Total 50.9 5 25.5 17.7 1.1 Soybean oil meal 6.2 2.5 2.5 .3 .3 Silage 44 7 2 5 23 17 4 .8 Coefficient of digestibility for silage .... Cow No. 8 Nutrients consumed, silage (55) 87.2 (46) 5.8 (56) 44.1 (67) 27.9 (50) 1.8 Nutrients digested Total 53.5 4.9 26.7 18.9 1.4 Soybean oil meal 6.2 2.5 2 5 3 .3 Silage 47.3 2.4 24.2 18.6 1.1 Coefficient of digestibility for silage .... (54) (41) (55) (67) (61) fiber and crude fat. The digestibility of the crude fiber of corn stover silage obtained by Hamilton and Rusk on cattle was 66.7 percent, as compared with 57.8 percent obtained by Tangl and Weiser on sheep. It is a noticeable fact that the differences in the coefficients obtained in the two investigations are all in favor of the cattle, except the co- 1987] CORN STOVER SILAGE FOR BEEF Cows 475 TABLE 6. SUMMARY OF COEFFICIENTS OF DIGESTIBILITY OF THE COMBINED RATION OF CORN STOVER SILAGE AND SOYBEAN OIL MEAL Cow No. Dry substance Crude protein N-free extract Crude fiber Ether extract Period I I.. 59 53 64 68 68 2 56 56 55 68 70 3 57 53 62 68 65 4 61 60 65 69 65 Average 58.2 55.5 61.5 68.3 67.0 Period II 5 55 53 54 64 68 6 53 52 55 62 59 7 58 61 59 67 62 8 57 57 57 67 68 Average 55.8 55.8 56.3 65 64.3 Averaare for Periods I and II 57.0 55.6 58.9 66.6 65.7 efficients for crude fat, which have little significance because of the small amount of ether extract in corn stover silage. The question whether or not different genera of ruminants digest roughages with the same efficiency has not been satisfactorily an- swered. Investigations comparing the digestive powers of cattle and sheep for the same feed are not numerous, and the evidence obtained in the majority of these is unsatisfactory in view of the use of only one or two animals. A cursory glance at the results of almost any diges- tion trial in which two. or more animals are used will show that con- siderable differences in digestion coefficients occur between individual animals of the same kind. Bartlett 2 has carried out a series of digestion experiments with sheep and steers in which he compared the digestibility of seventeen different rations by sheep and by steers. Of the seventeen rations, eight were roughages or largely roughages and the remainder were con- centrates or largely concentrates. The average coefficients of digestibil- ity for the dry substance, crude protein, and crude fiber of the eight roughages were determined to be as follows: By steers By sheep Dry substance 61.6 58.3 Crude protein 49 . 5 50 . 3 Crude fiber.. . 61.2 55.1 Difference in favor of steers + 3.3 o Bartlett concluded that the steers used in his experiments "had a greater capacity for digesting coarse fodders low in protein, like tim- othy hay and corn fodders, than sheep," and the above figures, espe- cially, indicate that this is true. He further states: "It is evident from 476 BULLETIN No. 291 [May, TABLE 7. SUMMARY OF COEFFICIENTS OF DIGESTIBILITY OF CORN STOVER SILAGE Cow No. Dry substance Crude protein N-free extract Crude fiber Ether extract Period I 1.. 57 37 62 68 67 2 53 39 52 68 63 3 53 30 59 68 61 4 58 45 63 69 63 Average 55.3 37.8 59.0 68.3 63.5 Period II 5 51 35 51 64 65 6 50 33 52 62 47 7 55 46 56 67 50 8 54 41 55 67 61 Average 52.5 38.5 53.5 65.0 55.8 Average for Periods I and II 53.9 38.2 56.3 66.7 59.2 Coefficients of digesti- bility for combined ration 57.0 55.6 58.9 66.6 65.7 TABLE 8. PERCENTAGES OF DIGESTIBLE NUTRIENTS IN CORN STOVER SILAGE Dry substance Crude protein N-free extract Crude fiber Ether extract Period I 15.7 .68 8.3 6.4 .34 Period II 13.2 .64 6.7 5.2 .28 Average* 14.5 .66 7.6 5.8 .31 "The average percentage of dry substance in the two samples of silage used was 26.72. TABLE 9. COMPARISON OF COEFFICIENTS OF DIGESTIBILITY OF CORN STOVER SILAGE OBTAINED BY DIFFERENT INVESTIGATORS Hamilton and Rusk (with cattle) Tangl and Weiser (with sheep) Difference in favor of cattle Dry substance 53.9 51.2 2.7 Crude protein 38.2 32.9 5.6 N-free extract 56.3 56.2 .1 Crude fiber 66.7 57.8 8.9 Crude fat 59.2 68.1 8.9 a study of these results and others before published that as great dif- ferences in digestion coefficients will occur between sheep, individually, as is likely to occur between sheep and steers." Jordan and Hall 3 made a compilation of the results of American digestion experiments up to 1898, and concluded that "American ex- periments neither confirm nor disprove the general assumption of Ger- 1927] CORN STOVER SILAGE FOR BEEF Cows 477 man experimenters that the different genera of ruminants digest coarse fodders with practically the same efficiency." In discussing this question Armsby 4 states: ". . . . it would ap- pear that in the case of the coarser and less digestible forms of forage a distinct difference exists in favor of cattle." The evidence, showing a greater utilization of the nutrients, especially the crude fiber, of the coarser roughages by cattle, is much more consistent for the rough- ages derived from the corn plant than for the hays. In Table 10 are given the results of experiments as reported by several investigators comparing the digestibility of the same kind of TABLE 10. COMPARISON OF DIGESTIBILITY OF THE SAME KINDS OF FEED BY STEERS AND BY SHEEP Coefficients of digestibility Investi- gator and reference Dry substance Crude protein N-free extract Crude fiber Ether extract Corn silage 1 steer 68.1 53.8 14.3 75.6 66.4 9.2 63.1 60.0 3.1 72.9 64.9 8.0 67.4 62.5 4.9 44.0 21.5 22.5 65.0 56.0 9.0 46.7 50.9 4.2 56.9 46.7 10.2 58.6 55.8 2.8 69.7 54.9 14.8 75.3 68.6 ~6.7 64.1 65.0 .9 74.4 68.2 6.2 66.8 61.6 5.2 77.6 63.6 14.0 81.9 70.6 11.3 67.2 57.8 9.4 79.8 69.9 9.9 74.4 68.1 6.3 76.6 68.3 8.3 89.5 88.5 1.0 68.3 75.5 7.2 72.3 59.3 13.0 79.2 77.8 1.4 Frear' Armsby 8 Bartlett 1 Bartlett 1 Armsby' 2 sheep Diff. in favor of steers. . . Corn silage 3 steers 2 sheep Diff. in favor of steers . . . Learning corn silage 2 sheep Diff. in favor of steers. . . Corn fodder (Sanford corn) 2 sheep Diff. in favor of steers. . . Corn fodder 2 steers 1 sheep Diff. in favor of steers . . . roughage from the corn plant by cattle and by sheep. It is to be re- gretted that a larger number of animals was not used in these compara- tive experiments. These direct comparisons and the less direct comparison made in Table 9 all indicate consistently better utilization by cattle than by sheep of the nutrients from the roughages derived from the corn plant. While the evidence is not sufficient to warrant a definite conclusion, it is quite probable that cattle do digest roughages from the corn plant better than do sheep. If this is true, it is also reasonable to suppose that the same is true of all coarse roughages low in protein, altho the available evidence on this point is less conclusive. In their investigation Tangl and Weiser also determined the di- gestibility of ordinary dry corn stover (averaging 85.0 percent dry substance) with sheep. A comparison of the coefficients of digestibility of corn stover and corn stover silage is made by these authors, and a 478 BULLETIN No. 291 [May, table given by them is copied in slightly different form in Table 11 of this bulletin. These data show no difference in the digestibility of dry substance, a difference in favor of the dry corn stover of 3.4 per- cent in the digestibility of the crude protein, and of 2.8 percent in that of the nitrogen-free extract, and a difference in favor of the silage of TABLE 11. COMPARISON OF COEFFICIENTS OF DIGESTIBILITY OF CORN STOVER AND CORN STOVER SILAGE* Digestibility of Difference in favor of Corn stover silage Corn stover Corn stover Corn stover silage Dry substance 51.2 32.9 56.2 57.8 68.1 51.2 36.3 59.0 53.5 58.3 3.4 2.8 4.3 9.8 Crude protein N-free extract Crude fiber Crude fat 'From Tangl and Weiser (loc. tit.). 4.3 percent for crude fiber, and 9.8 percent for crude fat. These differ- ences are small, and when the total dry substance consumed from both feeds is found to have averaged only 520 grams of corn stover daily per head, and the corn stover silage 528 grams, the differences are in- significant. TABLE 12. PERCENTAGE COMPOSITION AND PERCENTAGE OF DIGESTIBLE NUTRIENTS IN WHOLE CORN SILAGE, CORN STOVER, AND CORN STOVER SILAGE Composition Fresh Dry matter in Whole corn silage* Corn stover silage b Corn stover (field) Whole corn silage* Corn stover silage b Corn stover (field) Dry substance 20.0 1.7 11.1 5.4 .7 1.1 26.7 1.7 13.4 8.7 .5 2.4 60.0 4.6 30.1 20.6 .8 3.9 100 8.5 55.5 27.0 3.5 5.5 100 6.4 50.1 32.6 1.9 9.0 100 7.7 50.2 34.3 1.3 6.5 Crude protein N-free extract Crude fiber Crude fat Crude ash Digestible nutrients Crude protein .9 7.7 3.5 .5 .7 7.6 5.8 .3 1.7 17.8 13.2 .6 4.5 38.5 17.5 2.5 2.6 28.4 21.7 1.4 2.8 29.7 22.0 .9 N-free extract Crude fiber Crude fat "Lindsey, Haskins, Smith, and Beals (loc. tit.), average of 50 analyses. b Hamilton and Rusk. Lindsey, Haskins, Smith, and Beals (loc. tit.), average of 47 analyses. CORN STOVER SILAGE FOR BEEF Cows 479 The composition and percentage of digestible nutrients of whole corn silage, corn stover, and corn stover silage are given in Table 12. The data concerning the whole corn silage and corn stover are taken from the compilation by Lindsey, Haskins, Smith, and Beals, 7 and that for the corn stover silage from the present investigation. STOVER SILAGE ABOUT TWO-THIRDS AS VALUABLE AS WHOLE CORN SILAGE It is evident from the data in Table 12 that there is no great change in chemical composition brought about by ensiling corn stover, and further that the availability of the nutrients to ruminants is prac- tically the same. The increased palatability of the silage, the conse- quent smaller waste in feeding, and the fact that there is no loss of material from exposure to rain and wind, insure a much greater ulti- mate utilization of the nutrients of the corn crop when the stover is put in the silo than when it is left in the field. A comparison of the nutrients available in the stover silage with those in the whole corn silage shows about 85 percent as much total digestible nutrients in the stover silage as in the same weight of whole corn silage. However, ex- tensive feeding trials at this Station indicate that in practical feeding stover silage is only about two-thirds as valuable as normal silage, pound for pound on fresh basis. METABOLIZABLE ENERGY OF CORN STOVER SILAGE In addition to the regular routine analyses, the gross energy of the feed, orts, feces, and urine was determined by means of a calori- metric bomb. The metabolizable energy was computed by deducting from the gross energy of the feed consumed the energy of the feces, urine, and methane. The simple digestion apparatus used for these experiments was not provided with means for measuring the methane produced, so the en- ergy loss due to this gas had to be calculated. Armsby has shown that an average of 4.5 grams of methane are produced for every 100 grams of carbohydrates digested by a ruminant. 8 For the heat of combustion of methane Armsby 9 uses the figure 13.344 large calories per gram. Thus to calculate the energy loss due to gaseous fermentation for an animal during a collection period, the sum of the weights in grams of the nitrogen-free extract and crude fiber digested during the period, divided by 100 and multiplied by 4.5, gives the weight in grams of methane produced. The weight in grams of methane produced multi- plied by 13.34 gives the energy content of the methane in calories. This represents a loss of energy to the animal, and is deducted from the energy of the feed. Table B of the Appendix gives, for each cow, the total dry sub- stance, total nitrogen, and gross energy of the feed consumed, and of 480 BULLETIN No. 291 [May, the feces excreted; the total digestible carbohydrates, their methane equivalent in grams and in therms of energy; the total digestible or- ganic nutrients; and the nitrogen and energy of the urine. An accurate computation of the metabolizable energy of a feed or ration must involve a correction for the nitrogen gained or lost by the animal. If the animal is losing nitrogen during the period, it must be recognized that part of the energy of the urine has originated from partially oxidized body protein. According to Rubner 10 the potential energy of the urine is increased by about 7.45 calories for each gram of urinary nitrogen coming from the oxidation of body protein. There- fore, in case of a negative nitrogen balance, indicating that body pro- tein is being broken down, for each gram of nitrogen in the urine above that derived from the feed, equal to the negative nitrogen balance, 7.45 calories must be subtracted from the gross energy of the urine. On the other hand, when nitrogen is being stored in the body, as indi- cated by a positive nitrogen balance, 7.45 calories must be added to the gross energy of the urine for each gram of nitrogen stored, since this amount of metabolizable energy is being retained in the body. For example, Cow No. 1 had a negative nitrogen balance of 50 grams for the whole period. Therefore 50 times 7.45 calories, or 372.5 cal- ories must be subtracted from the gross energy of the urine to give the metabolizable energy due to the feed alone. Cow No. 5 showed a pos- itive balance of 53 grams of nitrogen, so that 394.9 calories are added to the gross energy of the urine. Table D of the Appendix gives the nitrogen balances of the cows. Table E shows the calculation of the metabolizable energy. The metabolizable energy calculated as described above, of course gives the metabolizable energy for the ration as fed, which included one pound of soybean oil meal. In order to correct for this small quan- tity of concentrate, and to secure the metabolizable energy derived from the corn stover silage alone, figures suggested by Professor Armsby are again used. According to Armsby 11 the metabolizable energy per pound of digestible organic matter in oil meals and concen- trates high in protein is between 1.996 and 2.177 therms for ruminants. The average of these two figures is 2.087 therms. The total digestible organic matter furnished by the soybean oil meal was 5.63 pounds to each cow: 5.63 multiplied by 2.087 gives 11.75 therms of metabolizable energy obtained from the ingestion of the soybean oil meal. Therefore, subtracting 11.75 therms from the total metabolizable energy in the combined ration for each cow gives the metabolizable energy derived from the corn stover silage alone. The metabolizable energy of the combined ration and of the corn stover silage alone is given in Table 13. The average metabolizable energy for corn stover silage alone is 1.57 therms per pound of digestible organic matter in the silage (Table 1927] CORN STOVER SILAGE FOR BEEF Cows 481 TABLE 13. METABOLIZABLE ENERGY: SUMMARY (Therms) Metabolizable energy of combined ration Metabolizable energy of corn stover silage alone Cow No. Total Per kilogram dry substance consumed Per pound digestible organic matter Total Per kilogram dry substance consumed Per pound digestible organic matter Period I 1.. 96.5 79.9 63.1 87.2 2.03 1.94 1.83 2.08 1.97 1.57 1.62 1.44 1.56 1.55 84.75 68.15 51.35 75.45 1.90 1.78 1.62 1.93 1.81 1.52 1.56 1.35 1.50 1.48 2 3 4 Average . . Period II 5 85.8 85.0 80.3 87.8 2.04 2.02 2.02 2.07 2.04 1.75 1.76 1.63 1.69 1.71 74.05 73.25 68.55 76.05 1.88 1.87 1.86 1.92 1.88 1.70 1.71 1.57 1.64 1.66 6 7 8 Average . . Average for Periods I and II . . 2.00 1.63 1.85 1.57 13). Armsby 11 gives the figure 1.588 therms of metabolizable energy per pound of digestible organic matter obtained from roughages in general by ruminants. SUMMARY The average coefficients of digestibility of corn stover silage fed to eight beef cows were found to be as follows: dry substance, 54 percent; crude protein, 38 percent; nitrogen-free extract, 56 percent; crude fiber, 67 percent; and ether extract, 59 percent. The metabolizable energy of corn stover silage was found to vary for the eight cows from 1.35 to 1.71, with an average of 1.57 therms per pound of digestible organic matter. This value agrees almost ex- actly with Armsby's 11 figure of 1.588 therms per pound of digestible matter obtained from roughages for ruminants. The authors desire to express their thanks especially to Dr. H. H. Mitchell, Chief in Animal Nutrition, for his constant assistance and many helpful sugges- tions; to R. R. Snapp, Associate Chief in Beef Cattle, for the supervision of the preliminary feeding and handling of the cattle while at the barns; and to W. T. Haines for most of the work connected with the feeding of the animals during the collection periods, the sampling of feeds, compositing, and preparation of all samples for analysis. 482 BULLETIN No. 291 [May. LITERATURE CITED 1. TANGL, F., and WEISER, S. Landw. Vers. Sta. 74, 330. 1910-11. 2. BARTLETT, J. M. Maine Agr. Exp. Sta. Bui. 110. 1904. 3. JORDAN, W. H, and HALL, F. H. U. S. Dept. Agr., Office Exp. Sta. Bui. 77, 90. 1900. 4. ARMSBY, H. P. The nutrition of farm animals, 604. 1917. 5. FREAR, WM. Penn. Exp. Sta. Rpt., 54-68. 1890. 6. ARMSBY, H. P. Penn. Exp. Sta. Rpt. 16. 1892. 7. LINDSEY, J. B., HASKINS, H. D., SMITH, P. H., and BEALS, C. L. Compilation of analyses. Mass. Agr. Exp. Sta. Spec. Bui., pp. 13-15. Nov., 1919. 8. ARMSBY, H. P., and FRIES, J. A. Jour. Agr. Res. 3, 451. 1915. 9. ARMSBY, H. P. The nutrition of farm animals, 636. 1917. 10. RUBNER, M. Ztschr. Biol. 21, 316, 329. 1885. Ibid. 42, 303. 1901. 11. ARMSBY, H. P. The nutrition of farm animals, 650. 1917. APPENDIX TABLE A. WEIGHTS OF ANIMALS DURING DIGESTION TRIALS (All weights in pounds) Cow No. Weight at beginning of digestion trial Weight when placed in digestion stall Weight at end of digestion trial Loss in weight while in digestion stall Weight one week after end of trial Weight two weeks after end of trial Period I 1. . 1 270 1 290 1 215 75 1 320 2 I 315 1 310 1 220 90 1 335 3. .J. .. 1 150 1 140 1 110 30 1 160 4. . . 1 285 1 260 1 230 30 1 300 Average 1 255 1 250 1 194 56 1 279 Period II 5. .. 1 135 1 130 1 100 30 1 120 6 1 135 1 110 1 080 30 1 155 7 1 035 1 015 990 25 1 060 8 1 260 1 180 1 165 15 1 245 Average 1 141 1 109 1 084 25 1 145 TABLE B. NITROGEN AND ENERGY TABLE Cow No. Feed consumed Dig. carbohydrates Di- gestible organic nu- trients 26s. Feces Urine Total dry sub- stance kg. Total nitro- gen gm. Energy therms Total kg. Methane equivalent Dry sub- stance kg. Total nitro- gen gms. Energy therms Total nitro- gen gm. Energy therms gm. therms Period I 1... 47 5 612 203 9 25 1 125 15 61 4 19 4 307 83 9 355 8.9 2.... 41.1 594 176 8 19 7 887 11 8 49 3 18 1 .261 76.9 446 9.0 3.. 34 5 522 148 1 17 6 792 10 6 43 7 14 9 247 67 4 291 7.1 4 42.0 603 180.1 22.5 1 013 13.5 55.9 16.5 .239 70.7 378 8.8 Period II 5... 42.1 617 181 2 19 6 882 11 8 49 1 19 1 .290 75.5 274 7.7 6 42 621 180 9 19 4 873 11 6 48 4 19 6 298 76 8 332 7 6 7 39.7 594 170 8 19 6 882 11 8 49 3 16 6 232 68 3 316 10. 1 8 42.4 tilM 182.4 20.7 932 12.4 51.9 18.1 .267 73.6 392 8.9 1927] CORN STOVER SILAGE FOR BEEF Cows 483 TABLE C. DAILY COLLECTION DATA: PERIOD I Feed offered Day Silage Soybean oil meal Salt Water Orts Feces Urine Iba. Ibs. oz. Ibs. Ibs. Ibs. 26s. Cow No. 1 1... 50 50 50 50 50 50 50 1 1 1 1 1 1 1 1 1 .13 9.25 24.25 28.00 36.63 24.13 24.50 .38 .56 .69 1.00 .76 .40 .25 32.75 30.19 35.71 41.50 42.40 39.66 39.28 22.63 11.46 13.17 12.14 17.13 11.36 19.38 2... 3 4 6... 7 Total 350 50 7 1 2 .28 146.89 20.98 4.04 .58 261.49 37.35 107.27 15.32 Daily average. Cow No. 2 1... 50 45 45 45 45 45 45 1 1 1 1 1 1 1 1 1 24.69 11.69 41.88 38.44 47.19 35.50 29.19 8.06 7.75 2.13 2.75 1.31 1.09 1.23 32.56 39.13 42.78 47.77 48.98 43.49 47.08 15.69 15.88 17.16 22.34 19.72 23.22 18.77 2 3 4 6 7 Total 320 45.7 7 1 2 .28 228.58 32 . <>7 24.32 3.47 301.79 43.11 132.78 18.97 Daily average . Cow No. 3 1... 50 45 45 40 40 40 40 1 1 1 1 1 1 1 1 1 17.94 24.19 35.63 29.31 25.94 30.25 28.69 13.25 11.75 9.18 5.50 5.30 3.94 5.06 36.63 34.50 32.86 35.43 40.93 23.73 34.20 12.87 7.13 17.25 6.81 14.50- 12.15 11.44 2 3 4 5 6 7 Total 300 42.9 7 1 2 .28 191.95 27.42 53.98 7.71 238.28 34.04 82.15 11.73 Daily average . Cow No. 4 1 50 45 45 45 45 45 45 1 1 1 1 1 1 1 1 1 .06 13.31 20.44 29.00 31.00 24.63 21.38 7.94 4.00 2.44 1.65 2.30 .22 1.00 35.34 35.66 28.50 32.61 34.25 37.40 32.63 13.88 13.41 12.84 14.31 14.45- 17.72 16.22 2 3 4 5 6 7 Total 320 45.7 7 1 2 .28 139.82 19.97 19.55 2.79 236.39 33.77 102.83 14.69 Daily average. TABLE D. NITROGEN BALANCE (All weights in grams) Cow No. Nitrogen in feed consumed Nitrogen in feces Nitrogen in urine Nitrogen balance Period I 1. . 612 307 355 55 2 594 261 446 113 3 522 247 291 16 4 603 239 378 14 Period II 5 617 290 274 +53 6 621 298 332 9 7 594 232 316 +46 8 621 267 392 38 484 BULLETIN No. 291 TABLE C. (Concluded) DAILY COLLECTION DATA: PERIOD II Feed offered Day Silage Soybean oil meal Salt Water (Ms Feces Urine Ibs. Ibs. oz. Ibs. Ibs. Ibs. Ibs. CDW No. 5 1 50 50 50 50 50 50 50 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15.81 26.50 .00 44.44 16.56 26.94 42.63 .22 .44 .19 .49 .22 .40 1.13 43.29 39.75 35.19 43.19 43.19 42.69 38.69 12.20 10.19 19.91 15.69 14.31 15.66 12.81 > 3 4 5 6.... 7 Total 350 50 7 1 7 1 172.88 24.70 3.09 .44 285.99 40.87 100.77 14.40 Daily average . Cow No. 6 1. . 50 50 50 50 50 50 50 1 1 1 1 1 1 1 1 1 1 1 1 1 1 19.88 28.25 26.50 24.69 39.69 23.25 46.50 .24 .39 .42 1.24 .63 .90 .60 44.53 37.58 57.00 57.33 33.05 56.13 48.45 9.58 14.55 14.84 15.53 14.30 13.21 15.41 2 .3 4 6 7 Total 350 50 7 1 7 1 208.76 29.82 4.42 .63 334.07 47.73 97.42 13.92 Daily average. Cow No. 7 1 50 50 50 50 50 50 . 50 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .00 .00 26.69 20.31 21.75 .00 44.81 .85 1.10 3.04 3.43 7.19 2.42 7.00 43.36 31.43 23.86 31.83 39.15 38.98 28.64 16.84 13.63 11.56 18.31 11.66 14.75 14.15 2 3 4 6 7 Total 350 50 7 1 7 113.56 16.22 25.03 3.58 237 . 25 33.89 100.90 14.42 Daiily average. Cow No. 8 1. . 50 50 50 50 50 50 50 1 1 1 1 1 1 1 1 1 1 1 1 1 1 24.25 26.00 19.00 22.00 26.88 28.50 25.63 .18 .19 .17 .13 .23 .21 .09 50.74 36.56 45.05 37.88 38.56 38.90 42.28 16.03 14.03 17.03 18.15 18.00 18.47 15.09 2 3 4 5 6 7 Total 350 50 7 1 7 1 172.26 24.61 1.20 .17 289.97 41.42 116.80 16.70 Daily average . TABLE E. CALCULATION OF METABOLIZABLE ENERGY (All measurements in therms) Cow No. Energy of feed consumed Energy of feces Energy of urine Energy of methane Energy correction for nitrogen balance Total metabo- lizable energy Period I 1. . 203.9 83.9 8 9 15.0 .4 96.5 2 176 8 76 9 9 11 8 - 8 79 9 3 148.1 67 4 7 1 10 6 - 1 63.1 4 180.1 70.7 8.8 13.5 -.1 87.2 Period II 5 181.2 75 5 7 7 11 8 + .4 85.8 6 180 9 76 8 7 6 11 6 1 85 7 170.8 68 3 10 1 11 8 + 3 80.3 8 182.4 73.6 8.9 12.4 -.3 87.8 UNIVERSITY OF ILLINOIS-URBANA