Salmonella and Campylobacter prevalence and concentration on pasture-raised broilers processed on-farm, in a Mobile Processing Unit, and at small USDA-inspected facilities

The small-scale, pasture-raised poultry production model is a growing niche in the locally grown food movement. Research that focuses on the food safety of small-scale broiler processing methods is limited. The objective of this study was to compare Salmonella and Campylobacter prevalence and concentrations on pasture-raised broilers processed on-farm, in a small United States Department of Agriculture – Inspected slaughter facility (USDA-IF), and in a Mobile Processing Unit (MPU) pilot plant. A total of 120, 100, and 50 post-chill, pasture-raised broiler carcasses were sampled from each processing method, respectively. Pathogen prevalence and concentrations from whole carcass rinses were determined using a 3-tube Most Probable Number (MPN) method for Salmonella and direct plating method for Campylobacter according to the USDA-Food Safety and Inspection Service (FSIS) protocols. Both Salmonella prevalence and concentrations on-farm (89% and 1.78 MPN/carcass [95% CI: 1.60–1.96]), USDA-IF (43% and 0.78 MPN/carcass [95% CI: 0.58–0.98]) were significantly (P < 0.05) different. Salmonella was not detected on carcasses processed via the MPU. Campylobacter prevalence was not significantly (P > 0.05) different on carcasses processed by the three methods (70% on-farm, 82% USDA-IF, and 100% MPU). The mean log10 Campylobacter concentrations in MPU processed carcasses (5.44 log10 CFU/carcass [95% CI: 5.24–5.63]) was significantly higher (P < 0.05) compared to on-farm (2.32 log10 CFU/carcass [95% CI: 2.06–2.80]) and USDA-IF (2.44 log10 CFU/carcass [95% CI: 2.03–2.85]). Based on the results of this baseline study, most pasture-raised broilers processed by the three methods were contaminated with Salmonella and/or Campylobacter. Further research is needed to assess other potential risk factors such as farm and regional variations that may contribute to the differences in pathogensʹ prevalence and concentrations.