The gut flora of the chick

Abstract

The gut flora of domestic animals has been studied extensively in recent years, mainly in attempts to elucidate the mechanism of antibiotic stimulation of the growth of young animals. There is strong reason to believe that the effect is mediated through the gut flora (Jukes, 1955), but considerable confusion exists because of the contradictory results obtained by different groups of workers. For example, when they gave chlortetracycline to chicks Dixon & Thayer (195 I) reported an increase in the numbers of lactobacilli, March & Biely (1952) reported a decrease, whereas Eisenstark & Sanford (1953) and Anderson, Cunningham & Slinger (1953) found no change. Coates, Dickinson, Harrison, Kon, Porter, Cummins & Cuthbertson (1952) have shown that in old premises that have housed several generations of chicks a growthdepressing condition exists which is transmissible and is counteracted by penicillin in the diet. I n this connexion, Elam, Jacobs, Fowler & Couch (1954) reported a decrease in 'clostridia' in penicillin-fed chicks, and that 'clostridia' fed to chicks in a clean environment depressed growth ; however, according to Smyser, Cleverdon, Kulp & Materson (1952) the numbers of Clostridium perfringens increased in the presence of dietary penicillin after 4 weeks, but chlortetracycline was without effect, and Brown & Luther (1950), Romoser (195 I) and Anderson, Cunningham & Slinger (195 I) found no reduction in numbers of anaerobes, and sometimes anincrease, with chlortetracycline.