Previous research into the genetics of broiler traits in a commercial breeding operation found a significant maternal effect on juvenile body weight, at 32 days of age, in addition to the additive genetic effect (Morris and Pollott, 1995). Since no nurture or imitative behaviour occurs between the dam and offspring in modem broiler production, any maternal effects are likely to be conferred to the offspring via the egg. This study attempts to investigate the nature of these effects.

Pedigreed eggs from two separate broiler breeding lines, one experimental male line and one experimental female line, were individually weighed prior to incubation. In total 2871 eggs were weighed, 1887 eggs from the experimental female line and 984 eggs from experimental male line.