Evaluation of the association between pen fecal accumulation and prevalence of Salmonella enterica shedding in swine

One of the recommended control measures for Salmonella enterica is improved or adequate fann hygiene. Although loosely defined, a component of good hygiene practice is to minimize animal contact with feces. Increased exposure to feces would he expected to increase the likelihood of transmission and fecal shedding of Salmonella enterica. There are indications in the literature that decreased animal contact with feces may result in a decreased risk for Salmonella enterica infection. Davies et al. demonstrated increased mean prevalence in open-flush gutter and dirt lot systems when compared to pigs housed on total slatted flooring systems. Paradoxically, three-site, all-in!all-out pig flow systems did not have a significantly different mean Salmonella enterica prevalence when compared to one-site continuous flow fanns. A similar incongruity is the evidence that in poultry barns, birds placed on used litter had lower risk of salmonella shedding than birds placed on clean litter.(5) Proposed mechanisms of this result are colonization with competitive flora from the used litter as well as an inhibitory environment for Salmonella enterica. The subjective nature of determining adequate hygiene as well as the presence of apparently contradictory results regarding hygiene and prevalence of Salmonella shedding in animals warrants inquiry into the question of what is good hygiene in respect to Salmonella shedding in animals