Prevalence of Salmonella in Broiler Flocks: Effect of Litter Water Activity, House Construction, and Watering Devices

Abstract

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.

Water activity of poultry litter: Relationship to moisture content during a grow-out

“…(Bernhart and Fasina, 2009;Carr et al, 1995;Eriksson De Rezende et al, 2001;Hayes et al, 2000). We suggest that differences observed between studies may be due to differences in the bedding materials, A w testing conditions (e.g.…”

“…Reid (2007) defined A w as the ratio of the fugacity of water in a system, and the fugacity of pure liquid water at the same temperature, where fugacity is a measure of the escaping tendency of a substance. A w can be approximated by the equilibrium relative humidity (ERH, expressed as a %) of a substance (Carr et al, 1995;Reid, 2007). In fact the two terms, A w and ERH, are effectively interchangeable (A w ¼ ERH/100).…”

“…It has been demonstrated that the microbiological properties of poultry litter are directly related to A w , and that maintaining litter below a critical A w value corresponds with reduced growth of pathogens including Salmonella and Escherichia coli as well as other microbiota (Carr et al, 1995;Chinivasagam et al, 2012;Eriksson De Rezende et al, 2001;Hayes et al, 2000;Himathongkham et al, 1999;Macklin et al, 2006;Payne et al, 2007). A w has also been related to physical handling properties of litter including cohesion, adhesion, compressibility and flowability (Bernhart and Fasina, 2009;Reed and McCartney, 1970;Roudaut, 2007).…”

Comparisons of Sampling Procedures and Time of Sampling for the Detection of Salmonellain Danish Infected Chicken Flocks Raised in Floor Systems

“…Several studies have described conditions in the litter which can influence the Salmonella status of broiler flocks (e.g. [27,28,21,10]. An increase in ammonia contents and pH in the litter is generally seen during the period when the broilers are raised in the houses, and these increases are detrimental to the survival of Salmonella [27].…”

Detection and monitoring of Salmonella in laying hen flocks

“…1989) that are dragged behind an operator who walks the length of the houses (Figs 5.4 and 5.5). This method proved more effective than limited litter sampling (Kingston 1981), but is subject to variability according to litter/manure moisture (Carr et al 1995) or details of application and sample processing (Opara et al 1992;Byrd et al 1997;Rolfe et al 2000). Limited sensitivity is indicated by the identification of additional positive flocks when the number of drag-swab assemblies used is increased (Caldwell et al 1994) which may be due to rapid overload of the available surface area of the swab (Rolfe et al 2000).…”