ARS | Publication request: Split marketing: A risk factor for Salmonella in market pigs?

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2007
Publication Date: July 8, 2007
Citation: Rostagno, M.H., Hurd, H.S., Mckean, J.D. 2007. Split marketing: A risk factor for Salmonella in market pigs?. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 85(1):202.

Technical Abstract: This study was designed to determine if split marketing affects Salmonella prevalence in market pigs, by comparing the Salmonella prevalence in the first group of pigs selected for slaughter (i.e., “First pull”) versus the last group of pigs selected for slaughter (i.e., “Close out”) from typical commercial finishing barns containing 800 - 1,000 animals. Nine paired observations were included in the study. Each paired sampling consisted in matched groups of pigs from the same barn as the “first pull” and the “close out” with a 4-week interval between groups. From each group, individual fecal samples (n = 45) and meat samples (n = 50) were collected, on-farm and at slaughter, respectively. In the laboratory, fecal samples were selectively enriched, and analyzed for the presence of Salmonella by a direct (antigen-capture) ELISA. Meat samples were kept frozen until processed, and then thawed, when the resulting liquid (“meat juice”) was collected and analyzed for the presence of antibodies against Salmonella by an indirect ELISA. All lots of finishing pigs studied were Salmonella-positive, based on sampling from “first pull” and “close out”. In 7/9 (77.8%) of the studied lots, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.3% (P<0.05) in bacteriologic prevalence, and 25.1% (P<0.05) in serologic prevalence from “first pull” to “close out” market groups. This study demonstrates that a significant increase of Salmonella prevalence occurs between the first and the last group of pigs from a finishing barn shipped to slaughter. In conclusion, split marketing affects the prevalence of Salmonella in market pigs with “close out” market groups constituting a higher risk for Salmonella contamination of pork products.