Location: Food and Feed Safety Research
Title: Selection for pro-inflammatory mediators yields chickens with increased resistance against Salmonella enterica serovar Enteritidis Authors
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 2013
Publication Date: February 25, 2014
Citation: Swaggerty, C.L., Pevzner, I.Y., Kogut, M.H. 2014. Selection for pro-inflammatory mediators yields chickens with increased resistance against Salmonella enterica serovar Enteritidis. Poultry Science. 93:535-544. Interpretive Summary: Salmonella are a leading cause of foodborne illness and can be transmitted through consumption of contaminated poultry; therefore, increasing a bird's natural resistance to Salmonella could improve food safety. Previous studies in our laboratory have shown that the rooster is important in determining the white blood cell's function and what types of chemical mediators they produce to help fight off infections. Since the innate immune response is the main way a young chicken protects itself and fights infections, we want to try a new selection method to identify roosters based on elevated production of chemical mediators. A preliminary selection trial showed individual roosters have varying levels of chemical mediators, and selection based on high or low levels are passed onto offspring. Based on these results, we hypothesized that selection of chickens for higher levels of chemical mediators would produce offspring that are more resistant to Salmonella. The objectives of this study were to use a new selection method to identify “high” and “low” roosters within a population of chickens and then use select roosters to produce offspring. Offspring from high roosters had higher levels of the inflammatory mediators and were more resistant to Salmonella compared to offspring from low roosters. The second generations showed the same trend. We also looked at how much feed the birds ate, and both high- and low-line birds were similar and had the same percent of breast meat. These findings show selection based on higher levels of chemical mediators is a new way to produce chickens that are naturally more resistant to Salmonella, one of the most important foodborne pathogens that impact the poultry industry. Use of more resistant birds by the poultry industry would significantly improve the safety of poultry products reaching the consumer.
Technical Abstract: Salmonella are a leading cause of foodborne illness and can be transmitted through consumption of contaminated poultry; therefore, increasing a flocks’ natural resistance to Salmonella could improve food safety. Previously, we characterized the heterophil-mediated innate immune response of two parental broiler lines and F1 reciprocal crosses and showed that increased heterophil function and expression of pro-inflammatory mediators corresponds with increased resistance against diverse pathogens. A preliminary selection trial shows individual sires have varying inherent levels of pro-inflammatory mediators and selection based on a high or low phenotype is passed onto progeny. Based on these results, we hypothesized selection of broilers for higher levels of the pro-inflammatory mediators IL-6, CXCLi2, and CCLi2 would produce progeny with increased resistance against Salmonella enteritidis. Peripheral blood leukocytes were isolated from 75 commercial broiler sires, screened, and five naturally high and low expressing sires selected to produce the first generation of “high” and “low” progeny. The mRNA expression of CXCLi2 and CCLi2 were significantly (P<=0.02) higher in the high progeny, and they were more resistant to S. enteritidis compared to low progeny. The next generation of selection yielded progeny that had differences (P<=0.03) in all three mediators and further improved resistance against S. enteritidis. FCR and percent breast meat yield were calculated and were equal while the high birds weighed slightly, but significantly, less than the low birds. These data clearly demonstrate selection based on a higher phenotype of key pro-inflammatory mediators is a novel means to produce broilers that are naturally more resistant to Salmonella, one of the most important foodborne pathogens that impact the poultry industry.