Comparison of blastoderm traits from 2 lines of broilers before and after egg storage and incubation

We examined the impact of egg storage on the hatchability of eggs from 2 lines (A and B) of commercial broiler breeders with known differences in fertility (line B slightly higher) and hatchability following egg storage (line A slightly lower). Eggs from both lines were stored in a 16°C room for 3 to 4, 10 to 12, and 17 d, the blastoderms were isolated, evaluated, and statistically compared. No significant interactions (line × duration of storage) were observed in the following traits: blastoderm diameter, total and percentage of viable blastodermal cells, stage of blastoderm development, and embryo weight and stage of development after 7 d of incubation. However, significant differences were observed when comparing line averages across storage treatments (diameter and total number of blastodermal cells) and storage treatment averages across lines (percentage of viable cells, and embryo weight and stages following incubation). To ascertain the basis for the observed differences in fertility, perivitelline sperm-hole numbers were determined in eggs within 72 h of lay (3 to 4 d storage group). Eggs from line B had a significantly higher number of eggs having greater numbers of sperm holes than eggs from line A. It is concluded that no single blastoderm trait or combination of traits can be definitively associated with the inter-line differences in hatchability following storage of eggs. Alternatively, differences in PVL sperm-hole counts between lines may be associated with the reported differences in fertility between the 2 lines.