Contamination of eggs by Salmonella Enteritidis in experimentally infected laying hens housed in conventional or enriched cages

Both epidemiologic analyses and active disease surveillance confirm an ongoing strong association between human salmonellosis and the prevalence of Salmonella enterica subspecies enterica serovar Enteritidis in commercial egg flocks. The majority of human illnesses caused by this pathogen are attributed to the consumption of contaminated eggs. Animal welfare concerns have increasingly influenced commercial poultry production practices in recent years, but the food safety implications of different housing systems for egg-laying hens are not definitively understood. The present study assessed the effects of 2 different housing systems (conventional cages and colony cages enriched with perching and nesting areas) on the frequency of Salmonella Enteritidis contamination inside eggs laid by experimentally infected laying hens. In each of 2 trials, groups of laying hens housed in each cage system were orally inoculated with doses of 1.0 x 10(8) cfu of Salmonella Enteritidis. All eggs laid between 5 and 25 d postinoculation were collected and cultured to detect internal contamination with Salmonella Enteritidis. For both trials combined, Salmonella Enteritidis was recovered from 3.97% of eggs laid by hens in conventional cages and 3.58% of eggs laid by hens in enriched cages. No significant differences (P > 0.05) in the frequency of egg contamination were observed between the 2 housing systems.