Genetic Capability of Young Layers for Survival after Salmonella entritidis Challenge

Problem statement: Genetic line differences in resistance of layer hens and young chicks to Salmonella entritidis have been identified through a lot of studies. That is why the agricultural industry was prepared for the potential phasing out of antibiotics for use in controlling bacterial pathogens. Early infection may result in long term colonization of layers with Salmonella entritidis, resulting in shedding into table or hatching eggs. Approach: This study was carried to evaluate the genetic factors underlying early response to Salmonella entritidis, genetic line differences in mortality and pathogen load at two sites (cecal lumen and spleen) were investigated. At day of hatch, chicks of four genetic lines were intra-esophageally inoculated with one of three doses of Salmonella entritidis phage type 13 A. Results: There was a significant effect (p≤0.001) of genetic line on chick 6 days survival. The effect of genetic line was significant (p≤0.05) on survivors’ Salmonella entritidis burden in cecal content but not on Salmonella entritidis load per gram of spleen. Salmonella entritidis pathogen load of the spleen and the cecal content were not significantly correlated, indicating that independent host mechanisms are partly responsible for these two traits. Conclusion: Future Salmonella entritidis control mechanism in poultry may be the same as it is used these days but it has to be for longer term sustainability, genetic resistance should be pursued. Sufficient genetic line variation should exists to suggest that it is feasible to effectively choose among pure breeder lines for those exhibits reduced Salmonella entritidis induced mortality and cecal content Salmonella entritidis pathogen load in young layer chicks.