Stocking density can influence SE susceptibility in laying hens
Higher stocking density can render layer hens more susceptible to Salmonella Enteritidis (SE), according to a report in Poultry Science.1
In two trials, the researchers placed groups of laying hens at two different stocking densities into colony cages. One group consisted of 40 hens housed 20 per cage at a stocking density of 973 cm2 (1.04733 sq. ft.) floor space per bird, and the other group consisted of 60 hens housed 30 per cage at a stocking density of 648 cm2 (0.697501 sq. ft.) floor space per bird. The investigators orally inoculated the birds with SE and then cultured internal organs 5 to 6 days later.
Significantly more SE (p < 0.05) was recovered from livers (75% versus 51.4%) and ovaries (51.4% versus 30.6%) of hens from the higher-density group, according to investigators from USDA’s Agricultural Research Service and North Carolina State and Michigan State universities.
However, they also found that spleens from hens in the higher-density colony cages were significantly (p = 0.0018) less often positive for SE compared to hens in conventional cages that were also challenged with SE but housed at the same density — 90.3% versus 68.1%.
Although stocking density can influence hens’ SE susceptibility, other housing system parameters might contribute to the outcome of infections, the investigators concluded.
1Gast R, et al. Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens housed in enriched colony cages at different stocking densities. Poult Sci. 2016; 95:1363-1369.