Environment and Stimulation of Growth of Chicks by Antibiotics

COATES et al. (1951, 1952) have reported the influence of environment upon the response of chicks to antibiotic. Groups of day-old chicks were maintained in 2 buildings and in each, were fed a basal diet without and with procaine penicillin G. One building had been previously occupied by chicks, whereas the other one was a newly constructed building where no chicks had been reared. Antibiotic response occurred in the “old” quarters, but not so in the “new” quarters. The chicks that were fed no antibiotic in the “new” quarters grew more rapidly than those fed the antibiotic in the “old” quarters. The authors concluded that the reason for the antibiotic response in “old” quarters was the presence of an “infection” that was sensitive to the antibiotic. We reported previously that withdrawal of antibiotic from the diet of chicks at 5 or 6 weeks of age caused a temporary retardation of …