|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2002
Publication Date: 2/1/2003
Citation: CHENG, H., SINGLETON, P.B., MUIR, W.M. SOCIAL STRESS IN LAYING HENS: DIFFERENTIAL EFFECT OF GENETIC-ENVIRONMENTAL INTERACTIONS ON PLASMA DOPAMINE CONCENTRATIONS AND ADRENAL FUNCTION IN GENETICALLY SELECTED CHICKENS. POULTRY SCIENCE. 2003. V. 82. P. 192-198. Interpretive Summary: In the modern poultry industry, the practice of housing hens individually or in multiple-hen battery cages could be one of the reasons that cause chickens to be stressed. Selecting strains for specific behavioral and physiological characteristics could help hens to cope with stress and improve chicken well-being. Two White Leghorn chicken lines have been selected based on high (HGPS) or low (LGPS) group productivity and survivability resulting from cannibalism and aggression. The present results showed that there are differential regulations of peripheral dopamine concentrations and adrenal function in response to different social stress. These changes indicate that genetic selection has altered animals' physiological response to stress. The results further suggest that HGPS hens have a better coping capability to social stress, and the line could be adapted by producers as a layer strain to limit or reduce suffering from the current managerial practices.
Technical Abstract: Two genetic chicken lines have been selected based on high (HGPS) or low (LGPS) group productivity and survivability resulting from cannibalism and aggression. The present study was to examine whether the different behavioral patterns and production are due to differential effects of genetic-environmental interactions on regulation of the neuroendocrine system in response to social stress. Chickens were randomly assigned to either single- or 10-hen cages at 17-wk of age. After a 7-wk housing, in the 10-hen treatment being similar to the original selective environment, compared to LGPS hens, HGPS hens had heavier adrenal glands (AGs, P<0.05), lower concentrations of plasma dopamine (DA, P<0.05), but no differences in concentrations of corticosterone (CORT). In the single-hen treatment, compared to the values in the 10-hen treatment from the same line, DA levels were greater in both HGPS and LGPS hens (P<0.05 and P<0.01), but the higher increase was found in LGPS hens. In the same comparison, both HGPS and LGPS hens had lower concentrations of CORT (P<0.05, respectively), but the latter also had less heavy AGs (P<0.05). The results indicated that interactions of gene-environment differently regulate DA and CORT systems in the present chicken lines. These differences may contribute to the line's unique behavioral and physiological characteristics. The data also indicate that multiple indicators should be used in the evaluation of an animal's coping capability and well-being.