Effect of competitive exclusion treatment on colonization of early-weaned pigs by Salmonella serovar Choleraesuis

Methods: Litters from three and two sows, respectively, were treated at birth and again at weaning with either of two porcinederived competitive exclusion cultures, one less diverse than the other. Another litter was treated as above with the least diverse competitive exclusion culture that had been supplemented with Bacteroides thetaiotaomicron, a bacterium implicated in effecting gut cell development. Three other litters served as placebotreated or untreated controls. All piglets were challenged at 15 days of age (1 day postweaning) with 106–107 colony-forming units (CFU) of Salmonella Choleraesuis. Rectal swabs (collected daily post challenge) and specimens (collected at necropsy 7–9 days postchallenge) were cultured for Salmonella Choleraesuis to assess the incidence of fecal shedding and colonization status of each piglet. Statistical analysis was not performed in this preliminary study due to the confounding of treatment effects with litter effects.