Prevalence of Salmonella in broiler flocks: effect of litter water activity, house construction, and watering devices.

Litter samples from 24 flocks of broilers and four flocks of broiler breeders were evaluated for Salmonella contamination, water activity (Aw), and total moisture content (MC). The drag swab (DS) monitoring system was used to collect samples to detect Salmonella contamination. Simultaneously, representative samples of the uppermost surfaces of dry (loose) litter and wet (caked) litter were collected for Aw and MC analyses. On dry litter surfaces, high Aw values (0.90-0.95) were associated with flocks Salmonella-positive using DS; low Aw values (0.79-0.84) were associated with flocks Salmonella-negative by DS; and transition Aw values (0.85-0.89) were associated with flocks having an increased risk for the presence of Salmonella. The association of high Aw values with Salmonella risk was not observed for wet (caked) litter surfaces. Observations suggest that limiting Aw in the litter base of broiler houses may create a less favorable environment for the multiplication of Salmonella and thus a more hygienic environment for broiler production.