Horizontal Transmission of Salmonella Enteritidis in Laying Hens Housed in Conventional or Enriched Cages

Housing type had no significant effect on the transmission of Salmonella Enteritidis infection in this American study.
calendar icon 1 December 2014
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The majority of human illnesses caused by Salmonella Enteritidis are attributed to contaminated eggs, and the prevalence of this pathogen in commercial laying flocks has been identified as a leading epidemiologic risk factor, according to Richard K. Gast of the Egg Safety and Quality Research Unit of the USDA Agricultural Research Service.

Flock housing and management systems can affect opportunities for the introduction, transmission, and persistence of foodborne pathogens in poultry, he and his co-authors there and at North Carolina State University explain in a paper in Poultry Science.

The animal welfare implications of different types of housing for laying hens have been widely discussed in recent years, but the food safety consequences of these production systems remain incompletely understood.

Their study assessed the effects of two different housing systems – conventional cages and colony cages enriched with perching and nesting areas – on the horizontal transmission of experimentally introduced Salmonella Enteritidis infection within groups of laying hens.

In each of two trials, 136 hens were distributed among cages of both housing systems and approximately one-third of the hens in each cage were orally inoculated with doses of 108 colony-forming units (CFU) of Salmonella Enteritidis (phage type 13a in one trial and phage type 4 in the other).

At regular intervals throughout 23 days following inoculation, cloacal swabs were collected from all hens (inoculated and uninoculated) and cultured for Salmonella Enteritidis.

Horizontal contact transmission of infection was observed for both Salmonella Enteritidis strains, reaching peak prevalence values of 27.1 per cent of uninoculated hens in conventional cages and 22.7 per cent in enriched cages.

However, no significant differences (P>0.05) in the overall frequencies of horizontal Salmonella Enteritidis transmission were evident between the two types of housing.

Gast and co-authors concluded their results suggest that opportunities for Salmonella Enteritidis infection to spread horizontally throughout laying flocks may be similar in conventional and enriched cage-based production systems.


Gast R.K., R. Guraya, D.R. Jones and K.E. Anderson. 2014. Horizontal transmission of Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages. Poultry Science. 93 (12):3145-3151. doi: 10.3382/ps.2014-04237

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December 2014

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