|Cheng, Heng Wei|
Submitted to: World's Poultry Science Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2004
Publication Date: 1/27/2005
Citation: Cheng, H., Muir, M.W. 2005. Genetic selection in poultry: physiological factors associated with production and survivability. World's Poultry Science Journal. 61:383-398.
Interpretive Summary: Genetic selection is an important tool for improving food production. In most traditional selection programs only traits directly related to productivity are considered. As a result, those breeding programs ignore traits that impact animal welfare. Using a method named group selection, chickens were selected for high and low production and survivability in the colony cages without beak trimming. Using the selected chickens as animal models, we have shown that productivity and well-being can be improved at the same time. These results clearly demonstrate that chickens' antisocial behavior is overcome by group selection. The new selection program can be adopted by scientists and the breeder industry in developing new chicken strains with greater adaptation to the production system, with an emphasis on improving animal well-being and maintaining economic efficiency.
Technical Abstract: Genetic selection is an important breeding tool for improving the animal's coping capability to modern production environments and for increasing economic benefits. However, over the past five decades, in most selection breeding programs, only traits directly related to productivity are considered. As a result, those breeding programs ignore traits that may impact animal welfare. To address this issue, a selection program termed 'group selection' was developed. This method takes into account competitive interactions by emphasizing performance of the group, rather than the individual. Results from the current studies have showed that birds' productivity and well-being can be improved at the same time. Compared to the reverse selected MBB birds (Mean Bad Birds), KGB birds (Kinder Gentler Birds) selected for high productivity and longevity had lower aggressive behaviours and cannibalism. KGB birds also had lower blood concentrations of 5-HT, dopamine, and epinephrine (P<.01), while a higher ratio of CD4+:CD8+ (P<.01). There was also a tendency for blood corticosterone to have higher concentrations (P = .08) in KGB birds. These results indicate that group selection altered the chickens' physiological homeostasis which is reflected in the line's unique coping ability with their domestic environments. The unique physical and physiological characteristics of each selected line provide new insights to facilitate the development of interventions aimed at ameliorating the adverse impacts of the intensified poultry industry. The cellular mechanisms involved in the selection program and potential strategies for improvement of animal well-being were discussed.