Technical Abstract: The modern intensification of the farm animal industry has led to widespread public concern regarding animal well-being and public health. Animal well-being is an indistinct concept and well-being is affected by multiple factors, including both internal and external events, which are regulated at different levels by different stress buffering systems including the nervous system. Genetic basis of different regulation of neuroendocrine changes in response to different stressors were studied in chicken lines divergently selected for high (HGPS) or low (LGPS) group productivity and longevity resulting from changes in cannibalism and flightiness in multiple-hen cages. Compared to HGPS hens, LGPS hens had greater blood concentrations of dopamine and epinephrine (P < .01). Blood concentrations of norepinephrine were not significantly different between the lines but the ratio of epinephrine to norepinephrine was greater in the LGPS hens (P < .01). The blood concentration of serotonin was also greater in the LGPS hens compared to the HGPS hens (P < .01). These results indicate that genetic selection for group productivity and longevity altered the chickens' physiological homeostasis that produced the line's unique coping ability with domestic environments.