Age had highly significant effects on both hen-day and hen-housed production. However, peak production was reached by all groups at about the 30th week of production. Both hen-day and hen- housed at peak production were much lower in the low uniformity flocks than the high uniformity flock. Petitte et al. (1982), in a study of two groups of broiler breeders of high and low uniformity, found that the more uniform flock exhibited higher egg production than the less uniform flock.