Further Evidence as to the Possible Mechanism Involved in the Growth-Promoting Responses Obtained from Antibiotics

Abstract

Data from two separate experiments show that the oral administration of penicillin, erythromycin, aureomycin, bacitracin, chloromycetin, furazolidone or p-chlorophenylarsonic acid failed to stimulate the growth of chicks reared in clean quarters. These supplements likewise failed to decrease the total number of clostridia present per gram of feces. This is further evidence that antibiotics stimulate growth by reducing the total number of clostridia in the intestinal tract of the chick and are ineffective in stimulating growth in a clean environment where the clostridia population is low.