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A N T I B I O T I C SUPPLEMENTS IN RATIONS FOR GROWING AND F A T T E N I N G LAMBS 1, 2, 3 E. E. HATFIELD, U. S. GARRIOUS, AND H. W. NORTON 4
University oJ Illinois ~
T H U G H the use of A Land Oswine is generallycertain antibiotics in the rations of poultry accepted, the value of antibiotics in therations of ruminants is less well established. The results of most experiments reviewed by Reid et al. (1954) have shown that small amounts of aureomycin or terramycin added to the rations of young calves resulted in increased gains in weight. However, with older cattle the results of aureomycin supplementation have varied from a favorable influence, as indicated by gains of yearling steers on a highroughage ration (Perry et al., 1954), to a depression of the apparent digestibility of crude fiber and decreased nitrogen retention in steers (Bell et al., 1951; and Horn et al., 1953 respectively). Neumann et al. (1951) were unable to obtain any benefit by supplementing the rations of yearling heifers with aureomycin. Likewise the results of experiments in which the effects of antibioticsupplementation in lamb feeding were studied have been variable and inconsistent. Colby et al. (1950a) reported that young lambs which received 9 rag. aureomycin, supplied with an APF supplement, per pound of concentrate (the first two weeks they received 18 mg. aureomycin per lb. of concentrate) gained less than their controls both before and after weaning. Moreover after weaning the feed intake of lambsin the lot receiving the ration supplemented with aureomycin was lower than that of the lambs in the control lot. Definite detrimental effects were observed in fattening lambs by Colby et al. (1950b) when 100 mg. aureomycin with or without all
x Published with the approval of the Illinois Agricultural Experiment Station. The authors wish to acknowledge the assistance of William Gaither and B. C.Breidenstein, Department of Animal Science in collecting data and for grading the lamb carcasses, in trials II and III, respectively; Dr. N. D. Levine, College of Veterinary Medicine, for parasite study; and Garvey Hayden and Richard Levis of Armour and Company, Chicago, in obtaining carcass data. ~The aureomycin HCI and aurofac were supplied through the courtesy of R. F. E]liott, LederleLaboratories, American Cyanamid Company, Pearl River, New York. The TM-5 and P-2 supplements were supplied through the courtesy of W. K. Warden, Pfizer and Company, Terre Haute, Indiana. Agricultural Experiment Station Statistician, Urbana, Illinois. Department of Animal Science, Urbana, Illinois.
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HATFIELD, GARRIGUS, AND NORTON
known B-vitamins were given daily by capsule. The lambs receiving the supplement lost weight while their controls gained more than 0.5 lb. daily. Lambs which received I00 rag. penicillin daily went off-feed, lost weight, and had diarrhea for ahnost a week; and lambs which weregiven 100 mg. streptomycin daily gained slightly less than their controls. Jordan and Bell (1951) were able to obtain favorable results by supplementing the ration of both suckling and fattening lambs with 5 to 15 rag. aureomycin per head daily. All lambs given the aureomycin appeared normal and had a higher rate of gain than their controls. The two lots of feeder lambs receiving the aureomycin...