Associations between animal-based welfare measures and the presence of Yersinia enterocolitica and Salmonella spp. as indicators of food safety in finishing pigs at slaughter plants in Northern Italy

The major current challenges for animal production are animal welfare and food safety (Rostagno, 2009). Animal welfare, which is a relevant part of the EU hygiene package, is usually dealt with as a separate issue and rarely directly connected to food safety hazards (Kijlstra and Bos, 2008). Stressful housing and management affect animals which, depending on their characteristics, may increase their receptiveness to pathogens. Since some pathogens do not lead to clinical signs of sickness, asymptomatic pigs could enter the food chain, contaminating carcasses and offal at slaughter and representing a threat to human health. The aim of this project was to assess the animal welfare status of finishing pigs on farm and its association with the occurrence of Yersinia enterocolitica and Salmonella spp. at slaughter plants in Northern Italy. Thirty batches of finishing pigs were assessed for animal-based measures according to the Welfare Quality® protocol for pigs on farm and at slaughter. A representative sample of five individuals per batch was tested for Y. enterocolitica and Salmonella spp. in tonsils and in mesenteric lymph nodes and gross pathological changes in these carcasses were recorded. Environmental faecal samples were collected from the same farms and tested for the same pathogens. The sum of positive batches to pen welfare measures were analysed by individual logistic regression against the sum of the Salmonella and Y. enterocolitica positive batches. Panic response to humans, pleuritis, pericarditis, space allowance (0.3-0.9m2/100Kg), mortality (2.6-4.5%), slatted floor, absence of enrichment material and absence of outdoor access all tended to be associated to Y. enterocolitica. White spot liver tended to be associated to Salmonella spp. Identifying strengths and weaknesses in animal husbandry systems serves to guide future actions which may address animal welfare (De Passillé and Rushen, 2005) and food safety legislative initiatives. Thus establishing the association between animal-based welfare measures and food safety hazards could support farmers in avoiding those practices likely to be associated with the occurrence and/or recrudescence of diseases. Further research in this field is needed.