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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Egg and Poultry Production Safety Research Unit » Research » Publications at this Location » Publication #313165

Title: Persistence of fecal shedding of Salmonella Enteritidis by experimentally infected laying hens housed in conventional or enriched cages

item Gast, Richard
item Guraya, Rupinder - Rupa
item Jones, Deana
item ANDERSON, KENNETH - North Carolina State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2015
Publication Date: 7/1/2015
Citation: Gast, R.K., Guraya, R., Jones, D.R., Anderson, K.E. 2015. Persistence of fecal shedding of Salmonella Enteritidis by experimentally infected laying hens housed in conventional or enriched cages. Poultry Science. 94:1650-1656.

Interpretive Summary: Because most human illnesses caused by Salmonella Enteritidis result from the consumption of contaminated eggs, the presence of this pathogen in commercial egg-laying flocks represents a threat to public health. Different poultry housing systems (including various types of cages and cage-free alternatives) have been widely debated in recent years in terms of animal welfare implications. Housing systems might also influence the potential for pathogens such as Salmonella to be introduced into and spread throughout egg-laying flocks, but the full food safety implications of housing are not yet clear. In the present study, 2 different types of housing (conventional and enriched cages) were evaluated for their effects on the length of time that experimentally infected hens would continue shed S. Enteritidis into their environment via feces. Enriched cages are colony-type units providing greater floor space per bird with perches and enclosed nesting areas. Laying hens housed in each cage system were orally infected with S. Enteritidis and fecal samples were collected from each group at weekly intervals and tested for the pathogen. The frequency of fecal shedding was significantly higher among birds in conventional cages than from those in enriched cages during the first 4 weeks after inoculation, but neither group continued shedding for more than 10 weeks. These results suggest that S. Enteritidis colonization of the intestinal tract and shedding in feces can differ between conventional and enriched cage-based production systems during the first month after infection, but this effect does not necessarily lead to any comparable difference in the eventual duration of fecal shedding.

Technical Abstract: : Because Salmonella Enteritidis can be deposited inside eggs laid by infected hens, the prevalence of this pathogen in commercial egg-producing flocks is an important risk factor for human illness. Opportunities for the introduction, transmission, and persistence of salmonellae in poultry are potentially influenced by flock housing and management systems. Animal welfare concerns have spurred the development of alternatives to traditional cage-based housing. However, the consequences of poultry housing systems for food safety have not been fully resolved by prior research. The present study assessed the effects of two different housing systems (conventional cages and colony cages enriched with perching and nesting areas) on the persistence of fecal shedding of S. Enteritidis by groups of experimentally infected laying hens. In each of two trials, 136 hens were distributed among cages of both housing systems and orally inoculated with doses of 108 cfu of S. Enteritidis (phage type 13a in one trial and phage type 4 in the other). At weekly intervals, samples of voided feces were collected from beneath each cage and cultured to detect S. Enteritidis. Fecal shedding of S. Enteritidis was detected for up to 8 wk post-inoculation by hens housed in enriched colony cages and 10 wk by hens housed in conventional cages. For both trials combined, the frequency of positive fecal cultures was significantly (P < 0.05) greater for conventional cages than for enriched colony cages at 1 wk (84.7 vs. 71.5%), 2wk (54.2 vs. 31.3%), 3 wk (21.5 vs. 7.6%), and 4 wk (9.7 vs. 2.8%) post-inoculation. These results demonstrate that the susceptibility of hens to intestinal colonization 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 fecal shedding.