Estimation of the on-farm Salmoenlla enterica prevalence in market swine
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The SafePork conference series began in 1996 to bring together international researchers, industry, and government agencies to discuss current Salmonella research and identify research needs pertaining to both pig and pork production. In subsequent years topics of research presented at these conferences expanded to include other chemical and biological hazards to pig and pork production.
The objective of this study was to compare fecal culture, meat juice ELISA, and culture of abattoir collected tissues for their ability to accurately estimate the on-farm prevalence of Salmonella enterica in market swine. Six herds, depopulated in the Accelerated Pseudorabies Eradication Program, were used. One-half of study pigs (50) were necropsied on-farm; the other half (50) at a commercial abattoir. The true farm prevalence (TFP), based on positive ileocecal lymph nodes, cecal contents, or fecal samples was estimated at 5.3%. This estimate was higher than any provided by a single sample type cultured. The seroprevalence (meat juice ELISA) was estimated at 20% using a cutoff of OD% > 40. Prevalence estimates from abattoir collected samples were much higher than the TFP; 39.9% of pigs were culture positive. This study shows that a single round of fecal collections will underestimate the true Salmonella status of a herd and that samples collected at the abattoir will overestimate the on-farm prevalence.