Transport to the Slaughterhouse Affects the Salmonella Shedding and Modifies the Fecal Microbiota of Finishing Pigs

Abstract

Contaminated pork is a significant source of foodborne Salmonellosis. Pork is contaminated at the slaughterhouse and the intestinal content is the predominant source of Salmonella for carcass contamination. The prevalence of Salmonella-positive pigs increases significantly when the time of transport to the slaughterhouse is longer than two hours. The hypothesis behind this study is that transport to the slaughterhouse increases the load of Salmonella in feces and determines a shift of the fecal microbiota in finishing pigs. Fecal samples were collected in a pig herd positive for Salmonella spp., the day before the transport and at the slaughterhouse. Salmonella loads were estimated by the most probable number (MPN) technique, according to the ISO/TS 6579-2:2012/A1. Moreover, the fecal bacteria composition was assessed by sequencing the V3-V4 hypervariable regions of the 16S rRNA gene. Our study showed that the load of Salmonella increases after transport, confirming that this phase of the production chain is a critical point for the control of Salmonella contamination. A lower richness and an increased beta-diversity characterized the fecal microbiota composition of Salmonella-positive animals after transport. In this stage, a natural Salmonella infection causes a disruption of the fecal microbiota as observed in challenge studies.

Salmonella Shedding in Slaughter Pigs and the Use of Esterified Formic Acid in the Drinking Water as a Potential Abattoir-Based Mitigation Measure

“…Although most Salmonella-infected fattening pigs remain asymptomatic while at farms, stressful situations such as the transport to the abattoir or the time at lairage can increase the load of Salmonella in feces in those previously infected pigs [8], and also increase the susceptibility to infection of the healthy ones [9]. There is evidence that on-farm Salmonella status has a significant influence on Salmonella shedding at slaughter [10,11].…”

Prophylactic Delivery of a Bacteriophage Cocktail in Feed Significantly Reduces Salmonella Colonization in Pigs

“…Overall, the microbial communities were very similar for groups T1 and T2 for all samples, showing phages did not have a detectable negative impact on the intestinal microflora. Interestingly, the relative abundance of Prevotellaceae was consistently higher in all samples collected from group T2, which is the family that has been previously shown to be associated with healthy pigs ( 40 , 41 ). Consistent with our study, another pig phage challenge study also observed that the relative abundance of the Prevotellaceae was higher in phage treated groups ( 42 ).…”

Salmonella spp. in Pigs Slaughtered in Small and Medium-Sized Abattoirs in Central Italy: Preliminary Results on Occurrence and Control Strategies

“…Salmonella can colonize pigs' gut, although most of them remain healthy carriers and the stress related to farm management, transportation, and early slaughtering stages (from unloading to stunning) may increase the prevalence of infected pigs entering the slaughtering process [11][12][13]. When animals are processed, contamination of pig carcasses can result from the skin, the intestinal contents, infected tissues, other carcasses, or slaughterhouse surfaces [14][15][16].…”