Faecal Salmonella shedding in fattening pigs in relation to the presence of Salmonella antibodies in three pig production systems

Human salmonellosis originating from pork is an important zoonotic disease, and the production of outdoor pigs may increase the risk of contaminating the food chain with Salmonella from environmental sources. The prevalence of faecal Salmonella shedding has therefore been compared in organic, conventional outdoor and indoor finishing pig herds in a Danish survey with participation of 34 herds. Individual faecal samples were collected from 30 to 50 pigs per herd before and after transport to slaughter and analysed for the presence of Salmonella. Further meat juice samples were collected from the pigs at slaughter and analysed for the presence of Salmonella antibodies. The results showed a low level of on-farm Salmonella shedding (overall prevalence 0.8%), while 2.3% of the pigs were shedding Salmonella at slaughter, with no significant differences between systems. The overall seroprevalence was 5.4% with no significant differences between systems. Pigs with Salmonella shedding on farm were more likely to also be shedding Salmonella at slaughter (P<0.001). The serological test result was a significant predictor of Salmonella shedding at slaughter in individual pigs from conventional systems, but not in organic pigs (P<0.05).