Effect of chronic hypoxia during the early stage of incubation on prenatal and postnatal parameters related to ascites syndrome in broiler chickens

To investigate the influence of hypoxia during the early stage of incubation on embryonic development and hatching events, and consequently on incidence of ascites in broiler chickens, one thousand fertile eggs were incubated in two commercial incubators. Half the eggs were incubated in a low altitude incubator until hatched. The second half were incubated in a high altitude incubator until day 10 and then transferred to a low altitude incubator. Day-old chicks from each group were housed and reared at a high altitude farm. Chicks from the high altitude incubator hatched earlier and showed significantly higher body weights than their counterparts in the lower altitude. High altitude embryos indicated significantly (P<0.001) higher plasma corticosterone, T3 and T4 levels at day 10 and 19 of incubation. During the growing period, high altitude hatched chickens indicated lower right ventricular hypertrophy and ascites mortality than the low altitude hatched chickens. These results indicated that early prenatal hypoxia due to high altitude may change the endocrine functions of embryos, enhanced embryo growth, shorten the hatching process of chickens and consequently decrease the incidence of ascites incidence in broiler chickens.