Genetic Variance and Covariance of the Components of Hatchability in New Hampshires ,

SINCE the early work of Pearl and Surface (1909), a great many studies have been made to determine the extent to which fertility and hatch of fertile eggs are controlled by heredity. Fertility must be considered a property of the parents only, since the trait being studied is no longer fertility once the gametes have united (Bernier, Taylor and Gunns, 1951). However, it has long been felt (Warren, 1927–28; Axelsson, 1932) that hatch of fertile eggs is a compound trait made up of two components. The first is the ability of the embryo to survive, and the second is the contribution of the dam to the extra-embryonic portion of the egg, which provides the milieu for embryonic development. Both embryonic viability and extra-embryonic maternal effects may be considered to have certain heritabilities which combine to make up the heritability of hatch of fertile eggs (Abplanalp and Kosin, 1953). This …