Supplementary Protein and the Response of the Pig to Antibiotics

Abstract

Soybean oil meal and menhaden fish meal were used to investigate the effect of the supplementary protein upon the response of the pig fed a single or a mixture of antibiotics. At a rate of 6 mg. per pound of diet either chlortetracycline or a mixture of equal parts chlortetracycline, procaine penicillin, and streptomycin increased the rate of gain of weanling pigs fed a corn-soybean oil meal diet and the rate and efficiency of gain of those fed the corn-fish meal diet. The magnitude of the growth response from antibiotics varied with the supplementary protein, it being considerably greater with menhaden fish meal as the supplementary protein. The growth increment produced by the mixture of antibiotics was superior to chlortetracycline alone, particularly with the corn-fish meal diet. In the absence of antibiotic the corn-fish meal diet which contained 0.10 percent tryptophan was significantly improved by the addition of 0.05 percent of DL-tryptophan. Copyright © . .