Five Years of Selection for Viability in White Leghorn Chickens

ONE method of decreasing mortality in adult chickens is by breeding strains which are resistant to diseases and disorders. An experiment to determine the feasibility of this method was started at the Alabama Experiment Station in 1935. The results of the first 6 years of work are reported in this paper. EXPERIMENTAL PROCEDURE The objective of the experiment, as outlined in 1935, was the development of strains of fowls resistant primarily to fowl paralysis, since at that time paralysis accounted for a large part of the adult mortality. Later, when mortality from paralysis was reduced considerably, the objective was expanded to include resistance to other diseases and disorders. Selection of breeders for resistant strain. The breeding females for the 1935 season consisted of hens two years of age or older and pullets. None of these were progeny tested and most of them were not pedigreed. They were mated to old . . .