Investigators assessed the effect of layer-hen stocking density on faecal shedding of S. Heidelberg and S. Typhimurium, both pathogens that can cause foodborne illness in humans.

Hens in the study were in a colony cage system with either 973 cm² per bird, considered low density, or 648 cm² per bird, considered high density.

There was a third group of layers in conventional cages with 648 cm² per bird, also considered high density, reports Richard Gast and colleagues of the USDA Agricultural Research Service, Athens, Georgia.

The investigators orally inoculated hens with either S. Heidelberg or S. Typhimurium then subsequently sampled voided faeces once weekly for 8 weeks.

The overall frequency of positive S. Heidelberg faecal cultures was 33% for the low-density colony cages, 46% for the high-density colony cages and 51% for the high- density conventional cages.

Shedding of S. Heidelberg continued for 8 weeks in all housing groups, but S. Typhimurium faecal shedding stopped after as few as 5 weeks in the low-density colony cages.

While stocking densities affected the faecal shedding of S. Heidelberg, no significant differences in S. Typhimurium faecal isolation were seen between the different housing groups, Gast and colleagues report in the September 2017 issue of Avian Diseases.[1]

The results show the impact stocking density can have on intestinal colonisation and faecal shedding in laying hens for some Salmonella strains, say Gast and colleagues.

References:

[1] Gast RK, et al. Frequency and Duration of Faecal Shedding of Salmonella Serovars Heidelberg and Typhimurium by Experimentally Infected Laying Hens Housed in Enriched Colony Cages at Different Stocking Densities. Avian Dis. 2017;61(3):366-371. https://doi.org/10.1637/11635-032517-RegR. Accessed December 11, 2017