Glucose metabolism in vivo in fed and 48 h starved goats during pregnancy and lactation.

1. Glucose turnover (i.e. glucose entry and utilization rates) in fed and 48 h starved goats during pregnancy and lactation was determined using a continuous infusion of [U-14C)- and [3-3H]glucose. 2. Glucose synthesis and utilization increased during pregnancy and lactation in fed but not in starved goats. 3. Recycling of glucose-C was approximately 10% in fed animals and 15-20% in starved animals and was unaffected by the stage of pregnancy or lactation. 4. Plasma glucose concentrations were maintained during pregnancy and lactation in fed goats but decreased during 48 h starvation in pregnant goats. Little change was seen in the plasma concentration of lipids and their metabolites during pregnancy and lactation in fed goats, but increases were observed after 48 h starvation. 5. The control of glucose metabolism in ruminants during pregnancy and lactation is discussed.