Productivity of Pullets Influenced by Genetic Selection for Social Dominance Ability and by Stability of Flock Membership ,

INTRODUCTION SOCIAL stress is usually associated with lowered productivity in chickens. Strange hens introduced into organized flocks are initially harassed and their egg production is depressed (Sanctuary, 1932; Guhl and Allee, 1944; Guhl, 1953; and Morgan and Bonzer, 1959). Low peck-order status also leads to a stressful intra-flock environment for the individual hen and is associated with lower productivity (see Guhl, 1953). Tindell and Craig (1959) confirmed the presence of intra-flock associations between social rank and productivity traits for the early part of the laying year, but found later egg production to be essentially uncorrelated with rank. They also compared 6 diverse genetic strains in intermingled and separate flocks. Inter-strain competition resulted in higher performance levels for the more aggressive strains; whereas, due to their lack of competitive ability, the less aggressive strains matured later, fed less often, had a lower rate of lay and poorer livability as compared to…