An examination of fertility, hatchability, embryo mortality, and chick weight in double versus single-yolked broiler breeder eggs

The objective of this study was to document the fertility and embryonic mor tality problems that result in the poor hatchability of double yolk (DY) ve rsus (single yolk) SY broiler breeder eggs. Both SY (n = 64) and DY (n = 14 1) eggs were collected from a commercial Hubbard Hi-Y flock and the eggs in cubated for 21 d. All eggs were candled and weighed at 7, 14 and 18 d, and any non-viable eggs were removed and broken open to assess fertility, and i f fertile, stage of embryonic death. Any unhatched eggs remaining after 21 d of incubation were broken open so that fertility, hatchability and embryo mortality could be calculated. Because there is the potential for two chic ks to hatch from a DY egg, fertility, hatchability, and embryo mortality we re calculated on a per yolk basis rather than an egg basis. Fertility, hatc hability, and hatchability of fertile eggs were significantly lower (P < 0. 05) in DY compared to SY eggs. Early- (<less than or equal to> 7 d of incub ation), mid (8-14 d of incubation), and late (greater than or equal to 15 d of incubation) embryonic mortality was significantly higher in DY vs. SY e ggs. Chick body weights were significantly greater in solitary chicks hatch ing from DY eggs versus chicks hatching from SY eggs.