|Cheng, Heng wei|
Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/29/2002
Publication Date: 9/1/2002
Citation: CHENG, H., SINGLETON, P.B., MUIR, W.M. SOCIAL STRESS IN LAYING HENS:DIFFERENTIAL DOPAMINE ANDCORTICOSTERONE RESPONSES FOLLOWING INTERMINGLING DIFFERENT GENETIC STRAIN CHICKENS. POULTRY SCIENCE. 2002. V. 81. P. 1265-1272. Interpretive Summary: Various strains of chickens differ in their response to physical stressors. Intermingling of chickens from different genotypic or phenotypic strains, such as during the recaging of layer hens from the grower house to the layer house, could be one of the reasons that cause chickens to be stressed. One solution to this problem is through genetic selection, i.e., ,selection of strain(s) with high stress resistance in response to social stress. Two genetic chicken strains have been selected based on high (HGPS) or low (LGPS) group productivity and survivability resulting from cannibalism and aggression. Previous studies have shown that the HGPS hens have a greater resistance to cold and heat stimulations and a better adaptation to colony cages than the LGPS hens. The data from the present study further suggests that the neuroendocrine system is regulated differently between the selected lines in response to social stress that was induced by intermingled with the Dekalb XL (DXL) hens. Previous studies have shown that DXL hens have higher cannibalistic and aggressive behaviors. Compared to the LGPS hens, the HGPS hens had lower concentrations of both corticosterone and dopamine in the experimental social condition. Both of corticosterone and dopamine have been used as stress indicators in mammals. The result suggests that the 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 strains have been selected based on high (HGPS) or low (LGPS) group productivity and survivability resulting from cannibalism and aggression. The objective of the study was to examine whether the different effects of genetic selection on the neuroendocrine system affect chickens from different strains in response to social stress. Based on previous studies, social stress was induced by randomly paired 17-week-old hens from the HGPS and LGPS hens and paired with the Dekalb XL (DXL) hens, respectively. Previous studies have shown that DXL hens have higher cannibalistic and aggressive behaviors. After a period of 7 weeks, compared to LGPS hens, HGPS hens had lower plasma concentrations of both corticosterone (CORT) and dopamine (DA) companied paired with DXL hen (p<0.05 and 0.01, respectively). Both CORT and DA have been used as stress indicators in mammals. Under the HGPS/LGPS social treatment, the concentrations of DA but not CORT were lower in the HGPS hens than in the LGPS hens (p<0.05 and p>0.05, respectively). The results indicate genetic selection for productivity and survivability in the present strains has differentially altered dopamine and adrenal systems in response to social stress, which are genetic and stress specific. The data suggest, compared to the LGPS hens, the HGPS hens have a better coping capability to social stress, which may consequently magnify their unique features in physical indexes, behavioral patterns, resistance to stressors and immunity.