Effect of breeder age and early hypoxic stimulation of the chorioallantoic membrane on vascularization, internal organ development, blood profile and chick organ histology

SUMMARY: This study examines how the combination of layer breeder age and oxygen concentration in the incubator impacts Chorioallantoic (CAM) vascularization, embryo and chick organs, blood profiles, and organ histology at hatch. Nine hundred (900) eggs from 33 to 50 wk ISA breeders were incubated at different O2 levels (15%, 17%, and 21%). Results showed significant interactions between breeder age and oxygen levels, affecting liver and heart weights, blood indices, and CAM vascularity. Hypoxic conditions led to adaptive changes in embryonic organs, with notable differences between breeder age groups, suggesting that mild hypoxia can influence compensatory growth, depending on exposure stages.