Observations on competitive exclusion for preventing Salmonella typhimurium infection of broiler chickens.

In 3 separate trials, groups of 180-200 one-day-old broiler chicks were treated with a lyophilized extract of breeder flock litter, an anaerobic culture of this extract, and an anaerobic culture of adult chicken feces, respectively. They were placed on litter, exposed at 3 days of age to Salmonella typhimurium placed in the drinking water and reared to 7-8 weeks (market age). Culture of litter samples, and of the intestines of all chicks that died or were killed throughout the growing period, showed that the incidence of infection at market age was significantly lower in treated chickens than in untreated controls.