II B R.ARY OF THL UNIVERSITY OF ILLINOIS Y\O. 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 The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Theft, 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 DEC 2 L161 O-1096 HIGH-PROTEIN CORN As a Source of Protein FOR DAIRY COWS By W. B. Nevens K. E. Harshbarger G. H. Rollins P. C. Burk K. E. Gardner K. A. Kendall Bulletin 586 UNIVERSITY OF ILLINOIS AGRICULTURAL EXPERIMENT STATION CONTENTS Page PREVIOUS INVESTIGATIONS 4 Chemical Composition of Corn 4 Feeding Experiments 5 PLAN OF FIELD WORK 6 COMPARISON OF PROTEIN CONTENTS AND YIELDS 8 FEEDING VALUE OF HIGH-PROTEIN CORN. .11 Digestion Trial With Rabbits 12 Digestion Trial With Cattle. 12 HIGH-PROTEIN SILAGE TESTED FOR MILK PRODUCTION 14 HIGH-PROTEIN CORN GRAIN TESTED FOR MILK PRODUCTION 17 SUMMARY AND CONCLUSIONS 19 LITERATURE CITED . ..21 Urbana, Illinois Publications in the Bulletin series report the results of investigations made or sponsored by the Experiment Station. High-Protein Corn as a Source of Protein for Dairy Cows By W. B. NEVENS, K. E. HARSHBARGER, G. H. ROLLINS, P. C. BURK, K. E. GARDNER, and K. A. KENDALL' GROWING ON THE FARM as much as possible of the protein needed is one means of keeping down the costs of milk produc- tion. When the ration for the dairy herd consists of grass pastures, grass hays, corn silage, and cereal grains, all of which are low-protein feeds, the amounts of protein supplied may not meet the needs of high- producing cows. This protein deficit has been overcome, in part, by making greater use of alfalfa, clovers, and other forage-type legumes and by enhancing the protein content of the forage through application of nitrogen to the pastures. Yet, even when forages grown on fertilized soil are part of the ration, it is still customary to include a high-protein supplement such as soybean meal. The expense of the supplement may be a con- siderable item in the cost of production and involves a direct cash outlay. The purposes of this investigation were to determine ( 1 ) whether high-protein corn fed as silage or as grain might replace a part or all of the protein supplement usually included in the dairy ration, and (2) whether high-protein strains of corn produced yields of forage and yields of protein in the forage equal to those of corn hybrids commonly grown in central Illinois. 1 W. B. Nevens, Professor of Dairy Cattle Feeding; K. E. Harshbarger, Assistant Professor of Dairy Production; G. H. Rollins, Assistant in Dairy Science; P. C. Burk, Assistant in Dairy Science; K. E. Gardner, Professor of Dairy Production; and K. A. Kendall, Associate Professor of Dairy Production. The authors were assisted in the investigation by W. H. Jenner, student in Dairy Science. They are indebted to R. W. Touchberry, Assistant Professor of Dairy Cattle Genetics, for advice concerning plans for the experiment and statistical studies of the data, and to E. B. Earley, Associate Professor of Soil Fertility, Department of Agronomy, for aid in planning the investigations. They also acknowledge the courtesy of the Plant Breeding division of the Department of Agronomy, University of Illinois, Funk Brothers Seed Company of Bloom- ington, Illinois, and the Lowe Seed Company of Aroma Park, Illinois, in fur- nishing the special strains of corn used in this investigation. 4 BULLETIN No. 586 [March, PREVIOUS INVESTIGATIONS A number of experiments have been undertaken with the purpose of producing high-protein corn and studying its chemical composition and feeding value. Chemical Composition of Corn In 1896 Hopkins (13)* began an experiment at the Illinois Station selecting corn for high and low content of protein and oil. He reported substantial increases and decreases in protein content after three gen- erations of selection. Smith (20) in a later report on the same experi- ment found that ten generations of selection had raised the protein level of the strain named High Protein from the original 10.92 percent to 14.26 percent. After fifty generations of selection, according to Wood worth, Leng, and Jugenheimer (22), the mean protein content of High Protein reached 19.45 percent and that of Low Protein was reduced to 4.91 percent. Earley, Carter, and Johnson (5) compared the protein, nicotinic acid, thiamine, and carotene content of kernels of medium-protein and Illinois High Protein corn grown at two different levels of soil nitro- gen and phosphorus. The concentration of these substances decreased rapidly as the kernels approached maturity. At both levels of soil fer- tility Illinois High Protein contained more protein, phosphorus, nico- tinic acid, and thiamine than mature kernels of the medium-protein corn. Illinois High Protein kernels, being white, contained very little carotene. Frcy, Hansen, Miller, and associates (7, 8, 9, 11, 15) in studies of the effects of selection upon protein quality in the corn kernel, found that the protein of low-protein corn was more nearly balanced nutri- tionally than that of high-protein corn. Zein, a protein which is low or lacking in some of the amino acids essential for nonruminant nutrition, formed a much larger percentage of the total protein of high-protein than of low-protein corn. Hamilton ct al. (10) reported that soil fertilization increased the weight of the corn kernel, and the content of protein, fat, and total phosphorus, but depressed the nicotinic acid content. It increased the percentage of total nitrogen present as zein nitrogen. Showalter and Carr (19) found that a larger part of the protein was present as xein and globulins in high-protein than in low-protein * Sec "Literature Cited," page 21. 1955] HIGH-PROTEIN CORN FOR DAIRY Cows 5 corn and the diamino acids formed about twice as great a percentage of the total protein in the high-protein strains. Hunt et al. (14) observed that the protein, niacin, and pantothenic acid contents of six corn hybrids declined rapidly as the corn ap- proached maturity. During the period August 24 to October 20 declines ranged from 20 to nearly 50 percent. Harshbarger et al. (12) reported that fertilization brought about an enhanced protein content in the leaf-stalk portion of corn forage when the crop was grown on soil low in fertility. Fertilization had little effect on the protein content of the grain portion. Mitchell, Hamilton, and Beadles (16) reported that the protein content of Illinois High Protein corn grown on nitrogen-deficient soil was 13.5 percent while on nitrogen- fertilized soil the protein content was 20 to 21 percent. In nitrogen-balance studies with rats, they found that the digestibility of the protein of corn increased slightly as the protein content of corn increased, but the biological value decreased considerably. They concluded, however, that the supplementation of the protein of corn with lysine and tryptophan will raise the biological value to levels that may approximate the biological value of meat protein. Feeding Experiments Other experiments with high-protein corn tested its nutritive value in feeding trials with beef cattle, dairy cattle, sheep, and swine. Snapp (21) found high-protein corn (13.2 percent protein on mois- ture-free basis) superior to standard hybrid corn for fattening yearling steers. Bond (1) found high-protein corn silage superior to standard hy- brid corn silage as a feed for the wintering of 400-pound beef calves. In another feeding trial, this time with yearling steers, he observed that a ration composed of high-protein corn and high-protein corn silage produced better general appearance and finish than a ration containing standard shelled corn, soybean meal, and corn silage. Burk (2) concluded from the results of a feeding trial in which silages made from high-protein corn and standard hybrid corn were fed to high-producing dairy cows that the extra protein of high-protein corn silage may replace part or all of the protein usually furnished in high-protein supplements. Ross (18) found that lambs fed high-protein corn grain (either 11 or 13 percent protein) made significantly greater gains than lambs fed low-protein corn (7 percent protein). He also found insignificant dif- 6 BULLETIN No. 586 [March, ferences in gains, and in feed required per unit of gain, in pigs fed either 8 percent or 14 percent protein corn at levels which provided equal amounts of corn protein, energy, and fiber. He pointed out that it is essential that high-protein corn, as well as low-protein corn, be supplemented with adequate vitamins, minerals, and amino acids if pigs are to make satisfactory growth. Dobbins et al. (4) reported that no difference was found in the nutritive value of two rations for pigs when the rations contained 15 percent protein and included either 8.2 percent protein corn or 11.7 percent protein corn. When 12.8 percent protein corn was fed, how- ever, the gains were significantly less than those made by pigs on lower-protein corn. Eggert, Brinegar, and Anderson (6) obtained nitrogen-retention values in the feeding of weanling pigs which were 37.2 percent for corn containing 10.6 percent protein and only 27.9 percent for corn containing 14.9 percent protein. Supplementation of the diets with lysine and tryptophan apparently corrected the deficiency and gave nitrogen-retention values which were nearly alike for both diets. PLAN OF FIELD WORK The corn was grown on three fields of the Dairy Science farm Field B, Field 17-20, and Field M. The chief soil types on Field B and Field 17-20 are Drummer silty clay loam, and Brenton, Catlin, and Flanagan silt loams. The soil types on Field M are Drummer silty clay loam, and Brooklyn, Thorp, and Flanagan silt loams. For many years just before the beginning of the experiment, Field M had been a part of a tenant-operated farm on which a cash-grain system of farming had been followed, and the fertility level of the field was low. The fertility of Fields B and 17-20, however, had been maintained at a high level through frequent growing of grasses and legumes, together with liberal applications of barnyard manure. Lime- stone had also been applied as needed. The tests were conducted during the years 1950-1953 inclusive. The corn was grown on Field B during three years of the tests, on Field M for two years, and on Field 17-20 for one. Most of the corn rows were 80 rods in length and the size of the plots ranged from 0.28 to 6.96 acres. Selection of kinds of corn. U. S. Hybrid 13 was selected as a standard and Illinois High Protein and three commercial strains were 1955] HIGH-PROTEIN CORN FOR DAIRY Cows 7 to be compared with it. U. S. Hybrid 13 is a yellow dent corn which is widely grown throughout the corn belt and is well adapted to central Illinois conditions. It has stiff stalks, a strong root system, and large, thick ears. It is early to midseason in maturity. Illinois High Protein, which was developed at the Illinois Station, is an open-pollinated strain of white dent corn. Its characteristics, as reported by Wood worth, Leng, and Jugenheimer (22), are lower ear height, lower plant height, a smaller percentage of erect plants, and more tillers per hundred plants than U. S. Hybrid 13. Its yield of grain is about half that of U. S. Hybrid 13, and it matures earlier. When grown on productive soils, the protein content of Illinois High Protein usually ranges from 16 to 20 percent while that of U. S. Hybrid 13 varies from 8 to 9 percent. The commercial strains, which are designated here as Corn C, Corn D, and Corn E, were characterized by larger and stronger plants than those of Illinois High Protein and had maturity dates about the same as that of U. S. Hybrid 13. The protein content of the grain of the commercial strains ranged from 11 to 15 percent. The high-protein strains of corn employed in the experiments were assumed to be representative of the best high-protein corn available at the time. Because of the progress made by corn breeders in improving the vegetative and yield characteristics of dent corn, as well as their development of strains of corn with a high content of protein, it was assumed that the strains of corn selected for this test did not repre- sent the ultimate goal in corn development and that further improve- ment was still possible. Harvesting and storing silage. Yields were obtained at the time the plots were completely harvested for silage. The loads were weighed and random samples were taken for determination of dry matter and other nutrients. One year, samples were taken of the standing crop. The samples were chosen by harvesting every one-hundredth plant in one or two rows, each 80 rods in length. Each sample was separated into ear and leaf-stalk portions. After chopping and subsampling, the subsamples were dried and saved for dry-matter and protein analysis. In making the silage which was used in the feeding and digestion trials, the forage of each of the strains of corn tested was harvested at a proper silage stage and stored separately in an upright silo. No water or conditioners were added to the forage. 8 BULLETIN No. 586 [March, COMPARISON OF PROTEIN CONTENTS AND YIELDS In this experiment the amount of protein produced per acre and the distribution of the protein between the ear and leaf-stalk fraction were matters of primary interest. Other criteria generally used in evaluating a particular strain of corn for its suitability as a silage crop were also considered. These include (1) yields of forage, (2) yields of dry matter in forage, (3) ability to reach harvest stage before frost, (4) ability to produce large yields of grain, (5) resistance to lodging and disease, and (6) feeding value of the silage. Yields of fresh forage. Since a farmer expects the forage crop to supply sufficient silage to feed his livestock, he often bases his estimate of the worth of such a crop upon the acre yield of fresh forage. All of the strains of corn tested in this trial gave satisfactory yields of fresh forage when grown on highly productive land (Fields B and 17-20, Table 1). When grown on Field M, a field known to be low in pro- ductivity, some of the yields were considerably below the 10-ton aver- age for the state. Yields of dry matter. The yields of dry matter in the forage varied considerably (a) from year to year, (b) between fields, (c) between nonfertilized and fertilized plots, and (d) between strains of corn (Table 1). Seasonal differences were noted in the yields from Field B. The yields obtained in 1951 were higher than those of the other two years in which this field was used. The yields of forage from Field M were considerably below those from Field B during 1950 and 1951, reflecting the difference in productivity between the two fields. In 1951 certain plots of Field M were fertilized and these plots furnished somewhat larger yields of forage than the nonfertilized plots. In each of the four years Illinois High Protein, with a single ex- ception, produced less dry matter per acre than any of the other strains of corn. On Fields B and 17-20 the dry-matter yields of Illinois High Protein in the different years w y ere from 18 to 40 percent less than those of U. S. Hybrid 13. The yields of the other high-protein strains were variable but, except for one plot of Corn D in 1951, were higher than those of Illinois High Protein. Delaying the harvest date resulted in higher percentages of dry matter in the forage and higher yields of dry matter. The effect of harvest date is illustrated in the yields of Fields B and M in 1950 (Table 1). 1955] HIGH-PROTEIN CORN FOR DAIRY Cows _ \0 TT i-H i-l NO 00 JS OOOOOON PO CN \OOvO -< 1-1 I-H t^ tN 10 O OOOOO /O 1 I / * *O OO OO CN '< f- OO ro O i-H \O OO rf "5 Tf CN CN OO CN O OO iO iO ON *^ OO CN CN OO PO NO PO CO r*5 PO ON O O O O JJ t~- PO O O ON ON ON ON ON t^ PO t> t D 10 PO OO O CN 10 t >O >O ""> >O vO ir> O >O CN a a a ^ .o ja 000000 CQCQCQM raCQCQCQ o ffi