Effects of Broiler Breeder Age on Egg Quality, Incubation Performance, and Early Progeny Physiological and Muscle Fiber Development.

This study evaluated the effects of breeder hen age on the incubation performance, embryonic development, and progeny quality of Cobb500 broiler breeders at 39, 51, and 69 weeks of age. A total of 870 eggs were collected, of which 810 were incubated; these were assigned to a completely randomized design with three treatments and nine replicates of 30 eggs. The average egg weights were 64.68, 69.77, and 72.40 g for breeders aged 39, 51, and 69 weeks, respectively. The incubation traits, chick quality at hatch, and embryonic development indicators, including relative embryo and liver weights, eggshell calcium content, serum glucose, and breast muscle fiber number, were evaluated. Eggs from 69-week-old breeders were heavier and resulted in heavier chicks at hatch and placement (p < 0.001), with lower dehydration than did chicks from 39-week-old breeders (p = 0.001). Hatchability, hatchability of fertile eggs, and hatch window were not affected by breeder age (p > 0.05). Embryonic mortality during Phase I was greater in eggs from 69-week-old breeders (p = 0.007). Embryos from younger breeders (39 weeks) presented greater relative developmental efficiency at 6 and 13 days of incubation (p ≤ 0.015). Progeny from older breeders (51 and 69 weeks) was associated with a greater incidence of physical quality scores between 86 and 90 (p = 0.050) and a greater number of breast muscle fibers in female chicks (p = 0.006). Eggshell calcium content, serum glucose concentration, and relative liver weight were not influenced by breeder age (p > 0.05). Breeder age significantly influences egg quality, embryonic development, and progeny characteristics, and advanced breeder age represents a trade-off between improved chick size and quality and increased early embryonic mortality.