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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 #306245
Title: Horizontal transmission of Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages

Author
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: 9/5/2014
Publication Date: 12/1/2014
Citation: Gast, R.K., Guraya, R., Jones, D.R., Anderson, K.E. 2014. Horizontal transmission of Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages. Poultry Science. 93:3145-3151.

Interpretive Summary: The majority of human illnesses caused by Salmonella Enteritidis are linked to the consumption of contaminated eggs, so the presence of this pathogen in commercial egg-laying flocks poses a significant public health risk. Different housing system options for poultry (including diverse types of cages and as cage-free alternatives) have been extensively discussed in recent years because of their animal welfare implications. These systems can also affect opportunities for Salmonella and other pathogens to be introduced into and spread throughout flocks, but the food safety implications of poultry housing remain incompletely understood. In the present study, two different types of housing (conventional and enriched cages) were evaluated for their effects on the horizontal (bird-to-bird) transmission of S. Enteritidis in laying hens. Enriched cages are colony-type units providing greater floor space per bird with perches and enclosed nesting areas. After laying hens were housed in each cage system, a few birds in each group were orally infected. Cloacal samples taken at weekly intervals indicated that similar percentages of uninoculated birds in the two types of cages became infected during the study period. The opportunities for Salmonella Enteritidis infection to spread horizontally within laying flocks appear to be similar for conventional and enriched cage-based production systems.

Technical Abstract: 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. Flock housing and management systems can affect opportunities for the introduction, transmission, and persistence of food-borne pathogens in poultry. The animal welfare implications of different types of housing for laying hens have been widely discussed, but the food safety consequences of these production systems remain incompletely understood. The present 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 S. Enteritidis infection within groups of laying hens. In each of two trials, 136 hens were distributed among cages of both housing systems and approximately 1/3 of the hens in each cage were orally inoculated with doses of 108 cfu of S. Enteritidis (phage type 13a in one trial and phage type 4 in the other). At regular intervals through 23 d post-inoculation, cloacal swabs were collected from all hens (inoculated and uninoculated) and cultured for S. Enteritidis. Horizontal contact transmission of infection was observed for both S. Enteritidis strains, reaching peak prevalence values of 27.1% of uninoculated hens in conventional cages and 22.7% in enriched cages. However, no significant differences (P > 0.05) in the overall frequencies of horizontal S. Enteritidis transmission were evident between the two types of housing. These results suggest that opportunities for S. Enteritidis infection to spread horizontally throughout laying flocks may be similar in conventional and enriched cage-based production systems.