Animal-welfare concerns have initiated the development of alternatives to traditional caged housing for hens. Unknown is whether different housing systems affect the introduction, transmission and persistence of Salmonella in poultry, which can be a source of illness in people, poultry research microbiologist Richard Gast, PhD, of USDA’s Agricultural Research Service, said at the 2015 Poultry Science association annual meeting.

Mr Gast and colleagues monitored faecal shedding among laying hens in two trials. In each trial, they distributed 136 hens into conventional or enriched colony cages and then orally inoculated them with S. enteritidis at weekly intervals, the researchers cultured samples of voided faeces to test for the pathogen.

S. enteritidis faecal shedding after inoculation was detected for up to 8 weeks among hens in the enriched colony cages and for up to 10 weeks among hens housed in conventional cages, he said.

For both trials combined, the frequency of positive samples after inoculation in conventionally housed hens versus hens in enriched colony cages was 84.7 per cent versus 71.5 per cent 1 week later, 54.2 per cent versus 31.3 per cent 2 weeks later, 21.5 per cent versus 7.6 per cent 3 weeks later and 9.7 per cent versus 2.8 per cent 4 weeks later. The difference between the two groups was significant (p < 0.05), Gast said.

“These results demonstrate that the susceptibility of hens to intestinal colonisation by S. enteritidis can differ between conventional and enriched cage-based production systems, although this effect does not necessarily translate into a corresponding difference in the longer-term persistence of faecal shedding,” he said.

*Gast R, et al. Persistence of faecal shedding of Salmonella enteritidis by experimentally infected laying hens housed in conventional or enriched cages. 2015 Poultry Science Association annual meeting, Louisville, Ky.