ARS | Publication request: Are there high and low Salmonella prevalence farms?

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. Are there high and low Salmonella prevalence farms?. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 85(1):203.

Technical Abstract: The objective of this study was to evaluate the stability of Salmonella prevalence in cohorts of finishing pig lots. Six finishing production sites were visited 6 times each. At each visit, 30 individual fecal samples were collected directly from the rectum. At slaughter, 50 individual meat samples were collected per lot. Fecal samples were selectively enriched, and analyzed for the presence of Salmonella. Meat samples were frozen, thawed, and the resulting liquid (“meat juice”) was analyzed for the presence of antibodies against Salmonella. All finishing production sites were Salmonella-positive in at least 2 fecal and 4 meat samplings. The overall bacteriological prevalence of Salmonella-positive pigs was 12.9% (95% C.I. 8.0-17.8%), whereas the serological prevalence was 35.4% (95% C.I. 24.5-46.4%; P<0.05). A wide variation in Salmonella prevalence (bacteriological and serological) of different finishing pig lots within individual production sites was found. The wide variation found did not allow the categorization of the sites (statistically) as high or low prevalence systems. Possible reasons for the variation found within production sites include; 1) occurrence of intermittent shedding and clusters, and 2) evolution and resolution of Salmonella infection epidemics. This study demonstrates that both, bacteriological and serological estimates of Salmonella prevalence in swine production systems are not consistent among cohorts over time. As a direct consequence of the results obtained in this study, a critical question comes up: Are there high and low Salmonella prevalence farms, or is it just a matter of timing?