|Cheng, Heng wei|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 10/23/2001
Publication Date: 12/20/2001
Citation: CHENG, H., SINGLETON, P.B., MUIR, W.W. PHYSIOLOGICAL INDICATORS OF HENS' WELL-BEING ARE RELATED TO GENETIC SELECTIONS FOR ADAPTABILITY TO CAGED PRODUCTION SYSTEMS. MEETING ABSTRACT. 2001. P. 325-334. Interpretive Summary:
Technical Abstract: Layer type chickens were selected for both high (HGPS) or low (LGPS) group productivity and longevity. Selection resulted in two lines with marked changes in cannibalism and flightiness in multiple-hen cages. The hypothesis was tested that the behavioral modifications may have been due to differential regulations of neuroendocrine and immune homeostasis. At 21 wk of age, data showed that the HGPS hens had higher percentages of blood lymphocytes and CD4+:CD8+ ratio of circulating T cells (P < .01). In contrast, the LGPS hens exhibited eosinophilia and heterophilia, and had a greater heterophil:lymphocyte ratio (P < .01). In addition, the 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 homeostatis that produced the HGPS line has higher immunity and lower stress response as compared to the counterparts. The data determined these physiological parameters could be used as indicators to evaluate an animal's ability to cope with stress, and the present selection program could be adapted by the breeder industry to improve laying hens' well-being.