|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2003
Publication Date: 6/1/2004
Citation: Cheng, H., Freire, R., Pajor, E. 2004. Different effects of endotoxin stress on chickens from different genetic lines: I. Sickness behavioral and physical responses. Poultry Science. 83:707-715. Interpretive Summary: The selection of chickens to current intensive production systems has resulted in remarkable increases in production efficiency, but some production practices may subject animals to stress. This situation creates an unacceptable production risk that may increase stress-related disease. One solution to these problems is to improve the animal's ability to cope with the intensive environments through genetic adaptation. The present study provides the evidence that genetic differences in chickens' productivity and behavioral styles are associated with hereditary plasticity of the behavioral and physiological homeostasis in response to stress and/or infection. The differential responses between the present selected chicken lines suggest that a LPS immune challenge can be a useful indicator to evaluate the efficacy of immunity in poultry. The present selected chicken lines may provide a new animal model for studying behavior and physiology of infection in farm animals. The impact of this research is that producers and scientists could use these results for developing new chicken strains with greater resistance to stress and disease, with an emphasis on improving animal well-being and maintaining economical efficiency.
Technical Abstract: Genetic variations in responses to lipopolysaccharide (LPS) challenge were studied in chicken lines divergently selected for high (HGPS) and low (LGPS) group productivity and survivability resulting from cannibalism and flightiness in colony cages and in a Dekalb XL (DXL) commercial line. Six-wk-old chicks (n=180) were randomly assigned to control or experimental groups and were injected intravenously with Escherichia coli LPS (5 mg/kg BW) or distilled saline (control). Sickness responses were measured at 6, 12, 24, 48 and 72 h following injection (n=10). Although LPS induced widespread sickness symptoms in all of the treated chicks, the reactions were in a genotypic- and phenotypic-dependent manner. Compared to both LGPS and DXL chicks, HGPS chicks had acute, transient behavioral and physical changes with a less effect on BW gain and organ development as well as core temperature, which were in the order HGPS<DXL<LGPS (P<0.05 and 0.01, respectively. The effects of heritable factors and LPS immune challenge on the differential responses between the present lines are discussed, which may reflect each line's unique adaptability to stress and resistance to infection and inflammation. The results suggest that the present chicken lines may provide a valuable animal model for investigating the effects of genetic-environmental interactions on the behavioral and physiological homeostasis in response to stress and disease.