Genetics of Egg Shape"

EXTERIOR egg quality comprises sev-eral characters. Size, as determined by weight only, has received more attention than any of the other external characters. Egg shell color has been studied by many investigators. However, the inheritance of shape of the egg of the domestic fowl has received only minor attention. Also, limited data available on the inheritance of egg shape are quite conflicting. Since egg shape is a quantitative charac-ter and little has been published on the in-fluence of certain genetic and environmental factors upon the shape of the egg, it seemed pertinent to investigate the possible effect upon variation in shape of such factors as pause, clutch position, size, and season of the year. These data are presented first since the findings have direct application to the problem of accurately measuring the true genetic egg shape of individual birds. REVIEW OF LITERATURE Curtis (1914) reported inter-individual variation in all egg characters. Her data indicate that egg shape, when measured by the length-breadth index, is less variable than egg size. Within the individual, length and breadth of the egg are less variable than the weight of the whole egg or any part of the egg. Many characters of the egg of the domes-tic fowl show definite and consistent sea-sonal fluctuations during the first laying year. Curtis (1914) noted a seasonal varia-* Authorized for publication on June 11, 1942