The Growth of Inbred and Hybrid Chicken Embryos

Abstract

INTRODUCTIONSTUDIES dealing with genetic differences in the rate of post-embryonic growth in the chicken have been numerous; while those dealing with differences in embryonic growth have been comparatively few. Moreover, studies that have dealt with genetic differences in avian embryonic growth have yielded conflicting results. Some workers have concluded that the genotype of the chicken embryo has no effect on its growth rate. Others have concluded that genetic differences in growth rate do exist.Byerly (1930), using Rhode Island Reds. White Leghorns, and the reciprocal crosses between the two, found slight but inconsistent differences in the size of embryos of the same age. He later reported (1932) that the growth rate of the chicken embryo was a function of its food supply. McNally and Byerly (1936) found they could explain such differences as they obtained in the rate of early embryonic growth in terms of differences in egg weight… .