Prevalence of Salmonella serotypes on pig carcasses from high- and low-risk herds slaughtered in three abattoirs

The aim of this study was to compare the prevalence of Salmonella serotypes at two different sites on pig carcasses from herds classified as high-risk or low-risk and to elucidate the relationship between carcass contaminatio n levels and serological status. Caecal samples and carcass surface swabs w ere cultured for Salmonella from a total of 210 pigs from low risk herds (< 19% of pigs in herd Salmonella seropositive) and 209 pigs from high risk h erds (> 32% of pigs in herd Salmonella seropositive) in three abattoirs. Me at juice samples were collected for analysis by ELISA. The prevalence of Sa lmonella in the caecal contents of "low-risk" pigs was 10%, which was signi ficantly lower than the 19% prevalence in "high-risk" pigs (p < 0.01). The corresponding figures for skin samples collected immediately post-eviscerat ion were 2% and 12%. The predominant Salmonella serotype in the caecal cont ents of both the low-risk and high-risk pigs was Salmonella Typhimurium. Sa lmonella Kentucky and Salmonella Derby were the most frequent isolates from the carcass surface swabs of low- and high-risk pigs respectively, There w as a positive association between seropositivity of pigs from high-risk her ds and caecal carriage (p < 0.05). Results showed that herd categorisation based on serological results was useful in predicting Salmonella isolation rates from caecal samples and surface swabs of slaughtered pigs.