|Cheng, Heng Wei|
Submitted to: World's Poultry Science Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2007
Publication Date: N/A
Interpretive Summary: A line of White Leghorns birds selected for high group productivity and longevity resulted in reducing cannibalism and flightiness in multiple-bird cage. The improvements in production and survival may have been due to changes of physiologic homeostasis. The objective of the present study was to test the hypothesis that genetic selection for high (KGB, Kind Gentle Birds) and low (LGPS) group productivity and survivability also alters regulations of neuroendocrine homeostasis. Birds were randomly assigned to individual cages at 17 wk of age. At 21 wk of age, blood concentrations of dopamine, epinephrine, norepinephrine, and serotonin were measured using HPLC assay. Blood corticosterone level was detected using radioimmunoassay. LGPS birds had significantly higher blood concentrations of dopamine and epinephrine than the KGB birds. The blood concentration of norepinephrine was not significantly different between the lines but the ratio of epinephrine to norepinephrine was higher in LGPS birds. The blood concentration of serotonin was also significantly higher in LGPS birds compared to KGB birds. In contrast, KGB birds tended to have a higher level of blood corticosterone. The results suggest that genetic selection for productivity and survivability with domestic behaviors alters the bird’s neuroendocrine homeostasis. There results further suggest that mechanisms underlying regulations of neurochemical and hormonal homeostasis are independently controlled by genes in the present selected lines.
Technical Abstract: This study demonstrates that genetic selection for high and low group productivity and longevity with alterations in cannibalism and flightiness affected the regulations of the neuroendocrine system of selected birds, and that CORT and monoamines, such as 5-HT, DA, EP and NE, were differently regulated by selection pressure. Compared to the reverse selected birds, KGB birds selected for higher productivity and longevity with higher domestic behaviors, i.e., low cannibalism and flightiness, may have a positive alterations in the neuroendocrine system, i.e., lower blood concentrations of 5-HT, DA and EP, and higher levels of plasma CORT, which may be associated with their better coping to a novel environment and greater resistance to stressors. The unique homeostatic characteristics of each selected line may provide a neurobiological basis for investigating effects of genetic factors on physiological functions of biogenic amines involved in productivity and longevity related to domestic behaviors. Present data suggest that some parameters of monoamines and hormones, such as levels of blood 5-HT, DA and EP as well as ratio of EP/NE, could be used as indicators for the animal’s well-being.