Prevention of Salmonella typhimurium caecal colonisation by different preparations for competitive exclusion.

The number of Salmonella typhimurium per gram of caecal contents of chicks, given orally prior to infection with different preparations containing protective intestinal flora, was significantly lower than in the control group. The best results were obtained when the lyophilised caecal rinses were given orally to 1-day-old chicks. Less effective methods of protection of the alimentary tract proved to be oral application to chicks of fresh faeces or lyophilised faeces and administration of the lyophilised caecal rinses with drinking water. Oral application of undefined anaerobic caecal culture to chicks proved to be the least effective of the methods investigated of protecting them against Salmonella colonisation, although even these results differed statistically from those of the controls. The percentage of infected birds 7 days after challenge confirmed the efficacy of oral application of lyophilised caecal rinses--only 30% of individuals from the group treated in this way proved to be Salmonella positive. In contrast, the percentage of infected birds in other experimental groups ranged from 50% to 75% and was 100% in the controls.