EFFECTS OF EGGSHELL QUALITY AND BROILER BREEDER AGE ON HATCHABILITY

The effects of eggshell quality and breeder age were assessed on egg weight loss during incubation, fertility, hatchability, and embryonic mortality. The trials involved hatching eggs from three commercial broiler breeder flocks of the same strain but of different ages. The eggs were divided according to specific gravity into two groups, thin-shelled (less-than-or-equal-to 1.080) and thick-shelled (> 1.080). Thin-shelled eggs displayed a greater increase in weight with breeder age and greater weight loss during incubation. Thick-shelled eggs showed an increased hatchability as a result of greater fertility and lower intermediate and late embryonic mortalities. Percentage of culls, pips, and rots were not related to shell thickness. Eggs from the younger flock had a higher weight loss during incubation irrespective of shell thickness. Hatchability and viability (hatchability of fertile eggs) were lower in the younger flock due to increased early and late embryonic mortalities. Fertility, culls, and pips were not affected by breeder age. The data may indicate the extent to which recent innovations in breeder management and in incubation technology have changed patterns of fertility and embryonic mortality.