Oral administration of neomycin to chickens experimentally infected with Salmonella typhimurium.

Groups of healthy chickens with a light experimental Salmonella typhimurium infection were fed on a diet containing 225 g per ton (1016 kg) of neomycin for two days. This brought about only a slight reduction in the incidence of chickens that were excreting S typhimurium in their faeces. Examination of caecal contents two days after the cessation of treatment revealed the neomycin had not had any effect in eliminating infection. In one experiment, the neomycin administration resulted in the emergence of enormous populations of Escherichia coli in the alimentary tract of treated chickens that possessed multiple antibiotic resistance of the transmissible type. For these reasons the practice of feeding broiler chickens on diets containing neomycin immediately before slaughter should be actively discouraged.