SOCIAL AND PHYSICAL ENVIRONMENTAL INFLUENCES ON CAGED SINGLE COMB WHITE LEGHORN LAYERS

Abstract

Pullets from two-way crosses between three highly inbred lines of Single Comb White Leghorns were housed in two sizes of commercial laying cages, two pullets per cage. Individual bird egg production records were kept when birds were 68–72 wk of age. During this period, peck order within each cage, fearfulness and body weight of each individual were determined. Differences between matings for fearfulness, body weight and egg production were not significant. However, in the case of egg production, both the mating × cage size and mating × cage tier interactions were significant. The genotype × environment interactions were interpreted to be due, in part, to varied behavioral response to the environment. Dominant birds had both a higher rate of egg production and heavier body weight than their subordinate cage mates. Birds housed in the larger cages (516 cm² per bird) were less fearful than those in the smaller cages (412 cm² per bird). Lower fearfulness was associated with higher egg production.