Altered plasma triglyceride-rich lipoproteins and triglyceride secretion in feed-restricted pregnant ewes

In late pregnancy, energy deficits in ewes can induce a metabolic imbalance, which often results in pregnancy toxaemia. This metabolic disorder is characterised by hypoglycaemia, hyperketonaemia, an increase in plasma concentrations of free fatty acids and by fatty infiltration in the liver. The purpose of the present study was to identify alterations in lipid and triglyceride-rich lipoprotein distribution and to evaluate triglyceride secretion in ewes during the third trimester of pregnancy, particularly in ewes with feed restriction. The study was performed on non-pregnant and on twin-and triplet-bearing pregnant Limousine x Romanov ewes fed a control or restricted diet. We show that in pregnant ewes, feed restriction resulted in strong lipomobilisation, as monitored by high plasma free fatty acid concentration, and in hypoglycaemia and hyperketonaemia. Plasma and very low density lipoprotein (VLDL) triglyceride concentrations were about four-fold higher in adequately-fed pregnant ewes than in non-pregnant ewes. Feed restriction in pregnant ewes resulted in VLDL triglyceride concentrations that were approximately two-thirds lower than in adequately-fed pregnant ewes. VLDL particles from pregnant ewes were found to be enriched in triglycerides, but to a lesser extent in feed-restricted pregnant ewes. Pregnant ewes that were fed an adequate diet exhibited greater triglyceride secretion rates (TGSR) than non-pregnant ewes. Feed restriction in pregnant ewes resulted in triglyceride secretion rates that were approximately 35% lower than those of pregnant ewes fed an adequate diet. Our results support the idea that exacerbated lipomobilisation in late pregnancy leads to profound lipid and lipoprotein metabolism disturbances.