INTERVENTIONS AND METHODOLOGIES TO REDUCE HUMAN FOOD-BORNE BACTERIAL PATHOGENS IN CHICKENS
Location: Poultry Microbiological Safety Research
Title: Horizontal transmission of Salmonella and Campylobacter among caged and cage-free laying hens
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 27, 2011
Publication Date: December 15, 2011
Citation: Hannah, J.F., Wilson, J.L., Cox Jr, N.A., Richardson, L.J., Cason Jr, J.A., Buhr, R.J. 2011. Horizontal transmission of Salmonella and Campylobacter among caged and cage-free laying hens. Avian Diseases. 55:580-587.
Interpretive Summary: In order to evaluate the potential for the horizontal transmission of the foodborne pathogens Salmonella and Campylobacter among table egg producing hens in different housing systems, nine laying hens were challenged with the foodborne pathogens Salmonella and Campylobacter. One week later, three challenged hens were commingled with twelve non-challenged hens in either conventional wire cages, on all wire slats, or on all shavings floors housing systems. After twelve days, all hens were euthanized and their internal organs sampled for the presence of Salmonella and Campylobacter. With the inclusion of residual Salmonella, the horizontal transmission of Salmonella among non-challenged penmate hens was significantly greater in the shavings system than in the caged and slats housing systems. Among challenged hens in each housing system, the percentage of cecum and reproductive tract samples positive for Salmonella were similar, and ascending infection from the cloaca likely resulted in contamination of the reproductive tract. The horizontal transmission of Campylobacter among non-challenged penmate hens was significantly greater on shavings than in cages, and the horizontal transmission of Campylobacter among non-challenged hens housed on slats was similar to that of hens housed in both cages and on shavings. The litter in the shavings pen most likely contributed to the survival of the Campylobacter that was shed through the feces of challenged hens. In summary, the potential for horizontal transmission of both Salmonella and Campylobacter (in inoculated environments) was found to be greater among hens housed on shavings covered floors than among hens housed in cages or slat systems.
In each of five trials, laying hens (56-72 wk-of-age) were challenged orally, intracolonally, and intravaginally with Salmonella and Campylobacter. One wk post inoculation, challenged hens (n=3) were commingled with non-challenged hens (n=12) in conventional wire cages, on all wire slats, or on all shavings floors. After 12 days, challenged and non-challenged hens were euthanized for sample collection. Ceca were aseptically collected from all hens, and the spleen, liver/gallbladder (LGB), lower (LRT) and upper (URT) reproductive tracts, and ovarian follicles (mature and immature) were aseptically collected from challenged hens only. Samples were equally divided and cultured separately for Salmonella and Campylobacter. There was no significant (P>0.05) difference in the horizontal transmission of Salmonella among non-challenged hens housed in cages (12%), on slats (15%), and on shavings (14%). Among challenged hens housed in cages, Salmonella was recovered only from the cecum (20%) and LRT (13%) samples. Salmonella was recovered from 25% of the cecum, 12% of the spleen, 19% of the LGB, 25% of the LRT, and 19% of the URT samples, collected from challenged hens housed on slats. Fifteen percent of the cecum, spleen, and LRT samples and 8% of the LGB and URT samples collected from challenged hens housed on shavings were positive for Salmonella. Horizontal transmission of Campylobacter among non-challenged hens was significantly lower in cages (28%) than on shavings (47%), with slats (36%) being intermediate. Campylobacter was recovered from 27% of the of the cecum, 13% of the LRT, 7% of the URT, and 17% of the follicle samples collected from challenged hens housed in cages. Among challenged hens housed on slats, Campylobacter was recovered from 44% of the cecum, 6% of the spleen, 19% of the LGB, 12% of the LRT, 6% of the URT, and 14% of the follicle samples. Among challenged hens housed on shavings, Campylobacter was recovered from 46% of the cecum, 8% of the LRT, 8% of the URT, and 40% of the follicle samples.