Characterization of the contribution of water activity and moisture content to the population distribution of Salmonella spp. in commercial poultry houses

Abstract

Because Salmonella spp. can be spread from the production environment to the consumer, strategies are required to control Salmonella. One such intervention involves control of the distribution of the organism in poultry litter. In this regard, we have attempted to determine whether Salmonella spp. are uniformly distributed throughout the litter of commercial poultry houses, or if they are unevenly localized to "hot spots" associated with high surface litter water activity (Aw) and high total moisture levels. Of the 86 houses sampled, 48 (55.8%) were positive for Salmonella spp. using a combination of the drag swab and targeted litter culturing methods. Data are presented that show that elevated Aw and percentage moisture content values representative of targeted litter samples or whole-house moisture status are not statistically predictive of Salmonella contamination, using either drag swab or targeted litter culture results as indicators of contamination. This study suggests that favorable environmental conditions for the growth of Salmonella are unequally dispersed in poultry houses. Because there is not equivalent distribution of salmonellae in the surface litter, the drag swab technique is apparently necessary to adequately survey for Salmonella spp. contamination. The findings further suggest that the development of a methodology to detect areas within houses that possess risk factors favorable for Salmonella growth must also include elevated Aw and percentage moisture content levels. This capability may enable a grower to detect and intervene in these targeted areas with neutralizing procedures, agents, or other substances to provide significant reduction of Salmonella or other poultry-associated food-borne pathogens.

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.…”

“…It has previously been recommended that the A w of poultry litter should be kept below 0.84e0.91 to restrict the growth of Salmonella and other microbiota (Chinivasagam et al, 2012;Eriksson De Rezende et al, 2001;Hayes et al, 2000;Payne et al, 2007). Carr et al (1994) reported that new bedding material (sawdust) had higher A w than litter and this was associated with the presence of Salmonella.…”

“…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).…”

Multiple-Antibiotic Resistance of Enterococcus spp. Isolated from Commercial Poultry Production Environments

“…Samples consisted of either poultry litter or swabs of poultry transport containers. Surface poultry litter was collected from 55 roaster and broiler chicken houses located on the eastern seaboard of the United States, as described previously (16). Over a period of 11 weeks in the summer of 1998, two swabs from each of 103 poultry transport containers representing 27 farms were periodically collected at a regional processing facility.…”

Material particulado y bioaerosoles en el aire de granjas de aves y conejos: cuantificación, caracterización y medidas de reducción

“…Although we found no correlation between dry matter content of the litter and Salmonella spp. concentration in the litter as described by Hayes et al (2000); when litter is dry it is more prone to becoming airborne as a consequence of increased ventilation rate or birds movement . In fact, we found strong correlations between airborne Salmonella spp.…”