Effect of feed intake level in late gestation on arterial blood concentrations of energy substrates, insulin and glucagon in the chronically catheterized gilt

The aim of the present work was to study, in the unstressed catheterized gilt, the effect of pregnancy on arterial substrate and pancreatic hormone concentrations in relation to the feed intake level. The experiments were performed on 14 pregnant gilts during the last month of gestation and 5 non pregnant gilts after cannulation of one carotid artery. Blood samples have been collected regularly after an overnight fast. After catheterization of the pregnant gilt, a 4 day-period is required to obtain steady-state conditions. As compared with non-pregnant animals fed on the same standard conditions (i.e. 2 kg/d: crude protein: 130 g/kg; digestible energy: 12.8 MJDE/kg), pregnant gilts exhibit similar and constant blood glucose, lactate, ketone body and plasma free fatty acid concentrations. By contrast, blood alanine concentrations progressively increases. A reduction of the feed intake level by 40% does not modify the blood glucose concentrations but leads to reduce blood lactate and alanine concentrations. On the contrary, plasma free fatty acid levels rise progressively with a limited increase in blood ketone body concentrations. While plasma glucagon concentrations are constant whatever the physiological state or the feed intake level, plasma insulin levels progressively decrease in the pregnant gilt. These data are discussed to display some aspects of the adaptation of the maternal metabolism in the gilt in late gestation.