Further Studies on Competitive Exclusion for Controlling Salmonellae in Chickens

Abstract

A native intestinal microflora of chickens which is protective against Salmonella readily transferred to pen-mates, and apparently to birds in adjacent pens. The microflora not only minimized infection resulting from exposure following colonization of the gut with microflora but significantly abbreviated the period of infection when introduced after a Salmonella infection was established in chicks. A microflora with undiminished protective activity sensitive to only a few commonly used anti-bacterials was established in a SPF [specific-pathogen-free] Cofal/Marek-negative population. Intestinal microflora from mourning doves was at least partially effective in protecting chicks against a naladixic-acid-resistant strain of S. infantis. In limited tests with 2 of 3 sources of protective microflora, the growth rate of chicks in the absence of salmonellae was significantly improved. Specificity of attachment between the glycocalyces of the protective microflora and of the intestinal mucosa is probably the mechanism of protection.