Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens of four commercial genetic lines in conventional cage and enriched colony housing

Authors: Gast, Richard; REGMI, PRAFULLA - Purdue University; Guraya, Rupinder - Rupa; Jones, Deana; ANDERSON, KENNETH - North Carolina State University; KARCHER, DARRIN - Purdue University

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2018
Publication Date: 7/23/2018
Citation: Gast, R.K., Regmi, P., Guraya, R., Jones, D.R., Anderson, K., Karcher, D. 2018. Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens of four commercial genetic lines in conventional cage and enriched colony housing. Poultry Science Association Meeting Abstract. 97: (E-Suppl.1): 112.

Interpretive Summary: Human infections with Salmonella Enteritidis are often attributed to the consumption of contaminated eggs, so the prevalence of this pathogen in commercial egg-laying flocks is a significant public health concern. Internal contamination of the edible contents of eggs results from bacterial colonization of reproductive tissues in systemically infected hens. Environmental conditions can exert powerful influences on the progress of avian Salmonella infections, but the food safety consequences of different housing systems for egg-laying hens remain incompletely understood. The present study assessed the invasion of internal organs by S. Enteritidis in groups of experimentally infected laying hens of four commercial genetic lines (designated as white egg lines W1 and W2 and brown egg lines B1 and B2). In two trials, groups of hens from each line were housed at a stocking density of 555 cm2 of floor space per bird in both conventional cages and colony units enriched with access to perches and nesting areas. All hens were orally inoculated with a dose of 5.75 × 107 cfu of a mixture of two strains of S. Enteritidis. At 6-7 d post-inoculation in each trial, hens were euthanized and samples of five internal tissues were removed for bacteriologic culturing. The overall frequency of recovery of S. Enteritidis was significantly greater (P < 0.05 in Fisher’s exact test) for intestinal samples from the two white egg lines combined than from the two brown egg lines combined in both conventional cage (72.2% vs. 50.0%) and enriched colony housing systems (66.7% vs. 37.5%). The frequency of intestinal isolation of S. Enteritidis from line B1 was significantly higher from hens in conventional cages (47.2%) than from hens in enriched colonies (22.2%), but no corresponding differences were observed for the other three hen lines. There were no significant differences between the four lines of hens or between the two housing systems in the frequency of isolation of S. Enteritidis from livers, spleens, ovaries, or oviducts. These results demonstrate that S. Enteritidis colonization can vary between genetic lines of egg-laying hens and that some lines are also subject to significant housing system influences on Salmonella susceptibility.

Technical Abstract: Human infections with Salmonella Enteritidis are often attributed to the consumption of contaminated eggs, so the prevalence of this pathogen in commercial egg-laying flocks is a significant public health concern. Internal contamination of the edible contents of eggs results from bacterial colonization of reproductive tissues in systemically infected hens. Environmental conditions can exert powerful influences on the progress of avian Salmonella infections, but the food safety consequences of different housing systems for egg-laying hens remain incompletely understood. The present study assessed the invasion of internal organs by S. Enteritidis in groups of experimentally infected laying hens of four commercial genetic lines (designated as white egg lines W1 and W2 and brown egg lines B1 and B2). In two trials, groups of hens from each line were housed at a stocking density of 555 cm2 of floor space per bird in both conventional cages and colony units enriched with access to perches and nesting areas. All hens were orally inoculated with a dose of 5.75 × 107 cfu of a mixture of two strains of S. Enteritidis. At 6-7 d post-inoculation in each trial, hens were euthanized and samples of five internal tissues were removed for bacteriologic culturing. The overall frequency of recovery of S. Enteritidis was significantly greater (P < 0.05 in Fisher’s exact test) for intestinal samples from the two white egg lines combined than from the two brown egg lines combined in both conventional cage (72.2% vs. 50.0%) and enriched colony housing systems (66.7% vs. 37.5%). The frequency of intestinal isolation of S. Enteritidis from line B1 was significantly higher from hens in conventional cages (47.2%) than from hens in enriched colonies (22.2%), but no corresponding differences were observed for the other three hen lines. There were no significant differences between the four lines of hens or between the two housing systems in the frequency of isolation of S. Enteritidis from livers, spleens, ovaries, or oviducts. These results demonstrate that S. Enteritidis colonization can vary between genetic lines of egg-laying hens and that some lines are also subject to significant housing system influences on Salmonella susceptibility.