Effects of hypoxia on the metabolism of embryos and chicks of domestic fowl.

Oxygen consumption and blood lactate concentration were measured in embryos (days 17-20) and chicks (days 0-7) in air and in 7-8% O2. The specific oxygen consumption in air increased up to day 4 after hatching. In 7-8% O2, the consumption decreased for all ages. The reduction was largest in the embryo (19% of normal) and smallest in the newly hatched chick (78% of normal). Blood lactate concentration increased markedly during exposure to 7-8% O2 at all ages. Although the embryo exhibited the largest percentage reduction in aerobic metabolism during hypoxia, the blood lactate concentration increased to the same level as in the newly hatched chick. A positive correlation between reduction in aerobic metabolism and blood lactate concentration was found in chicks. Thus, during hypoxia the embryo seemed to be able to reduce its total metabolic rate to a much greater extent than after hatching.