Selection for resistance to Marek's disease in conjunction with other economic traits in chickens.

Abstract

Selection for resistance to an artificial challenge with Marek's Disease (MD) agent reduced the incidence of this disease approximately 14.1% in the selected line as compared to the control line of a commercial female broiler strain of chickens. A second generation of selection for resistance to MD in conjunction with other economic traits yielded a decline in the previously noted genetic gain; however, the change in the estimated gain over two generations was not significant because it was within the interval of two standard errors of the difference. No large genetic correlations between MD and other economic traits were detected. A selection index utilizing combined information for different traits including MD resistance is described. The index considers the individual's record plus full and half sib information on several traits.