Purpose: To identify on-farm food safety practices that are specific to the unique conditions and needs of small-scale and/or bio-diversified farms (i.e., operations that integrate livestock and fresh produce). The objective is to assess risk factors and the prevalence of certain foodborne pathogens in livestock raised on small-scale diversified farms.
Methods: Twenty-one farms in California were enrolled in this cross-sectional study conducted in 2015. Seventeen (81.0%) were bio-diverse farms and 4 raised only livestock. Eleven raised more than one species (52.4%) and 18 (85.7%) keep poultry. Individual livestock feces and composite poultry samples were collected from the ground and were cultured for Campylobacter, Shiga toxin-producing Escherichia coli (STEC), and/or Salmonella; selected isolates were serotyped.
Results: Foodborne pathogens were found on 71.4% (15/21) farms at least once during the study. Out of 626 random samples collected, 301 (48.1%) were poultry and the remaining 325 were from non-poultry livestock. The overall Campylobacter prevalence was 6.9% (43/626) including isolations from poultry, swine, cattle, goats, and sheep. STEC O157:H7 was found in 1.9% (6/325) samples overall and all isolates were from beef and dairy cattle at one ranch. Prevalence of non-O157 STEC was 7.7% (25/325) including detections in cattle, goats and sheep. Overall prevalence of Salmonella was 0.8% (5/626), and all isolates were from chickens at two farms. STEC serogroups included O103, O111, O136, O182, O26 and O43. Salmonella serovars included Salmonella Agona, Salmonella Othmarschen and Salmonella Braenderup.
Significance: This study highlights the need to assess potential food safety risks associated with small-scale, pasture-based, diversified farms. Findings will provide scale-appropriate food safety metrics and recommendations for risk reduction to farms integrating crops and livestock.