Salmonella screening in pork slaughter flowchart

ABSTRACT

The aim of this study was to trace the sources of Salmonella contamination during the pig slaughter flowchart. Ten lots of pigs sent for slaughter were followed (four animals per lot), and two weeks before slaughter they were selected based on the presence or absence of Salmonella in their farm stalls. Stool samples were collected after stunning, and from the surface swabs of the carcass in different parts of the flowchart. Samples were also collected immediately after the animals left the dehairing machine, after opening the abdominal cavity, before the carcass entered the cooling chamber, and from jowl samples. The water samples used in the scalding tank were collected before commencing the slaughter process and after the passage of the animals. For the comparison of band patterns, the isolates were analyzed by rep-PCR. The percentage of isolation was 35.3% after stunning, 17.6% immediately after the animals left the dehairing machine, 17.6% after evisceration, 23.5% before entering the cooling chamber and 5.8% from the jowls. The serotypes obtained were Senftenberg, Idikan, Typhimurium, Heidelberg, Minnesota, Panama and Salmonella group O4,5. By repPCR analysis, it was found that Salmonella strains that reached the slaughterhouse in carrier pigs may not be eliminated during processing, thereby making its isolation from the carcasses possible. It was also observed that the strains introduced by animals can infect others in different stages of the slaughter flowchart, thus resulting in cross-contamination.