Delayed Appearance of Lactobacilli in the Intestines of Chicks Reared in a “New” Environment

Male chicks (1 day old; Vantress x Arbor Acre) were fed a basal folic acid-deficient diet, a 5% uric acid-containing diet with and without 5 mg/lb (453.5 g) of bacitracin and 20 mg/lb of sodium penicillin G, the basal diet supplemented with only the antibiotics, and the basal diet plus 500 mug/lb of folic acid. The chicks were reared in a room which had not been used previously for housing chickens ("new" environment). Bacteriological analyses of the contents of the small intestine revealed a decrease in numbers of streptococci and "anaerobic" bacteria in the chicks receiving dietary antibiotics. No persistent changes were seen in the numbers of coliform bacteria. Lactobacilli were not detected in any of the groups until 3 weeks after feeding.