The association between cleaning and disinfection of lairage pens and the prevalence of Salmonella enterica in swine at harvest.

A series of four field trials were conducted to evaluate the ability of a cleaning and disinfection procedure in swine lairage pens to reduce the prevalence of Salmonella enterica in slaughtered pigs. A cleaning and disinfection procedure was applied to lairage pens at a large Midwest abattoir. Each trial consisted of a cleaned (alkaline chloride detergent) and disinfected (H2O2 plus peracetic acid sanitizer) pen (treated) and a control pen, each holding 90 to 95 pigs for 2 to 3 h before slaughter. Ileocecal lymph nodes, cecal contents, and rectal contents were collected from 45 pigs from each study pen at harvest and cultured for S. enterica. In all trials, cleaning and disinfection reduced the prevalence of S. enterica-positive floor swabs in the treated pen (P < 0.05). However, the postharvest prevalence of S. enterica-positive pigs varied between trials. In trial 1, there was no significant difference in the prevalence of S. enterica in pigs between treatment and control groups. In trials 2 and 3, the prevalence of S. enterica was higher in pigs from treated pens versus pigs from control pens (91% versus 40%, P < 0.0001, and 91% versus 24%, P < 0.0001, respectively). In trial 4, the prevalence of S. enterica was lower in pigs from treated pens compared with pigs from control pens (5% versus 42%, P < 0.0001). This study indicates that cleaning and disinfection effectively reduces the amount of culturable S. enterica in lairage pens, but the ability of cleaned and disinfected pens to reduce the prevalence of S. enterica in market-weight pigs remains inconclusive.