|Cheng, Heng Wei|
Submitted to: Poultry Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2004
Publication Date: 7/25/2004
Citation: Jefferson, L., Cheng, H. 2004. Effects of acute stress on physical and hormonal responses in three genetic strains of laying hens. Poultry Science Meeting. 83(S1):361. Interpretive Summary:
Technical Abstract: Genetic selection for enhanced production may also affect an animals' ability to cope with stress. In this experiment, the effects of acute stress on physical and hormonal responses were examined in three genetic lines of laying hens: a line selected for high group productivity and survival (KGB), a line selected for low group productivity and survival (MBB), and a commercial line (DXL). All genetic lines were reared in separate cages in two environmentally controlled rooms, at 4 hens/cage (144 in2 /hen). At 17 weeks of age, hens housed in one room were transported to a laying facility and re-caged (transport and mixing stress). The re-caging procedure ensured that all hens were unfamiliar, with a single genetic line in the cage. Hens housed in the second room were reared without interruption and served as the controls. Both control and stressed hens were sacrificed 24 hours after treatment. Tissue samples and physical characteristics, including body weight, the right adrenal gland, and blood, were collected and analyzed for physical and physiological parameters associated with the stress response. There were no significant differences in heterophil to lymphocyte ratios, relative adrenal weights, and plasma corticosterone levels among the control hens from all three lines (P>0.05). Compared to their respective controls, the MBB hens tended to have a greater ratio of heterophils to lymphocytes (P = 0.06) than the KGB and DXL hens. The relative weight of the right adrenal gland was significantly increased in the KGB hens (P<0.001) but not in the MBB and DXL hens in compared with their respective controls (P>0.05). Compare to the controls, plasma corticosterone concentrations were increased in both KGB hens and DXL hens (P<0.05) but not in the MBB hens (P>0.05). These data support the hypothesis that genetic selection affects physical and physiological characteristics which may be indicative of animals' abilities to cope with stress.