Purdue University Agricultural Experiment Station Lafayette, Indiana
Mimeo AS-278 October 30, I960 (Final)
Amino acid (lysine and methionine) additions to beef supplements represent a new approach to improve the feedlot performance of cattle. It is well known that rumen microorganisms can make protein from urea and other non-protein nitrogen compounds to supply about one-third of the daily protein needs of cattle. Bacterial protein formed by biological synthesis in the rumen is subsequently digested in the stomach and intestine of the host animal. All of the ten essential amino acids necessary for growth can be synthesized from urea by means of the rumen’s microbial action. But there may be a few which are not synthesized rapidly enough for maximum performance when large amounts of urea are fed. Urea is limited in its use and value because, at present, we do not know all the nutrients required for maximum protein synthesis in cattle. Amino acid supplementation may be part of the answer.
This is the beginning of a long-time research program to design a new cattle supplement, high in urea, which can be fed at the rate of one pound per head daily.
Zinc bacitracin has not been tested extensively in cattle rations. To date,
,a majority of the experiments have indicated that aureomycin and terramycin are the most effective antibiotics for improving the performance of beef cattle. Early tests on bacitracin with cattle were negative, but since that time the formulation of this antibiotic has been changed. This experiment was designed to thoroughly examine the effects of zinc bacitracin on fattening steers when subjected to different types of supplement.
The objectives to this experiment are as follows:
1.	To compare a 32$ supplement fed at 2.0 pound daily with 64$ supplement fed at 1.0 pound for balancing a fattening ration.
2.	To determine the effect of adding lysine and methionine to a 32$ and a 64$ (14.8$ urea) supplement.
3.	To determine the effect of feeding BO mg. of zinc bacitracin daily to steers on different supplements.
Experimental Procedure
Twelve lots of six Hereford steer calves each were fed a basal ration of ground shelled corn (full-fed), 15-20 pound corn silage and either a 32$ or 64$ protein supplement on the same protein equivalent basis. The protein level of the 64$ supplement was increased by replacing soybean meal with urea. L-lysine HC1 and/or DL-methionine was added to the supplement so that each steer would receive 10 grams of the respective amino acids daily. The soybean oil meal and urea were adjusted when lysine and methionine premixes were added to keep the protein level the same. The composition of each supplement is given in Table 1.
y Acknowledgement is made to Commercial Solvents Corporation, Terre Haute, Indiana, for a grant-in-aid to support this project; to Chas. Pfizer and Company, Terre Haute, Indiana, for furnishing the L-lysine, and to Dow Chemical Company, Midland, Michigan, for supplying the DL-methionine.
LYSINE, METHIONINE AND ZINC BACITRACIN AS ADDITIONS TO SUPPLEMENT A AND TO A 64$ PROTEIN-UREA SUPPLEMENT FOR FATTENING BEEF STEERS 1/
W. M. Beeson, W. H. Gossett and T. W. Perry Department of Animal Science