Date Full Report Received


Date Abstract Report Received


Primary Investigator:

Ensuring the safety of pork is essential for producers in order to maintain animal and human health, and also to continue serving export markets. One barrier to this is the rising occurrence of Salmonella contamination in pork. In order to best prevent Salmonella in post-harvest pork, the pathogen must first be prevented from entering the farm-to-fork supply chain. Recently Salmonella enterica serotype I 4,[5], 12:i:- have been linked to swine feed and pork products. The magnitude of its presence in the U.S. and its pathogenicity are currently unknown. Therefore, the overall objective of this study was to give to the pork industry a better understanding of the ecology and distribution of Salmonella enterica and in particular of the serotype I 4,[5], 12:i:-; and collect valuable data for the development of effective intervention strategies both at pre and post-harvest level. In order to achieve these overall objectives, the specific deliverables were as follow:

  • determine the presence and distribution of Salmonella enterica population and in particular the prevalence of serotype I 4,[5], 12:i:- in commercial feed mills manufacturing feed;
  • characterize the distribution of Salmonella positive isolates in relation to sampling location and establishment-production associated risk factors.

    For objective 1, results indicated that 9 of the total 11 feed mills had at least one Salmonella positive site. From the total isolates, 49 (12.8%) were confirmed Salmonella: two isolates were identified in feed, while the other 47 on equipment and/or surfaces. A higher pathogen prevalence was observed in fall and summer season. A total of two ST and three STM were identified during the visits. These isolates showed a similar seasonal presence being found most commonly during fall and summer.

    For the second objective mill ID was the significant factor associated with the presence of Salmonella. Differences in management, geographical location, hygiene practices, quality of incoming raw ingredients, volume of feed produced, number of workers, and time the facility has been operational were all important variables for pathogen presence. No differences between mash and pelleted feed were observed, while production flow and plant design were identified as important in preventing microbial introduction and recontamination of finished feed. Worker shoes also represented an important vehicle for pathogen spread around the mill: control room and manufacturing floor area (zones with the most human flow) had the highest percentage of Salmonella samples.

    Overall the data gathered in this study shows the potential role of feed and feed mill environment as entry routes for Salmonella spp, ST and STM into human food chain. Hygiene, management, production flow, and cross-contamination within facility were all significant factors linked with pathogen contamination in mills. We found that both the mill and the season were significantly associated with the presence of Salmonella in the production facilities. These results contribute both to the implementation of biosecurity plans and other preventative strategies in feed mills and to understand Salmonella behavior at pre-harvest level.