Tissue glycogen and lactate handling by the developing domestic fowl.

The levels of glycogen and lactate in liver, intestine, yolk sac membrane and leg and breast muscle of domestic fowl from day 10 of "in ovo" development to day 5 after hatching compared with adults have been measured and compared with the circulating concentrations in blood of glucose and lactate. Glycogen stores in most tissues increased before hatching to attain a minimum around the eclosion and then increased to adult values in muscle and liver. Lactate maintained its plasma concentrations with higher effectiveness than plasma glucose, which increased steadily up to adult levels from hatching. The study of tissue vs plasma lactate concentration ratios suggests a general activation of lactate metabolism from hatching, coinciding with the ingestion of carbohydrate-based food. Both muscles studied, as well as intestine, seem to be net lactate producers; blood cells can speculatively be considered as lactate users and liver maintains its concentration of lactate very close to that plasma, suggesting a fast utilization of this material as well as liver being the main site for control of circulating lactate.