FETAL AND MATERNAL PLASMA-LIPIDS IN CHRONICALLY CATHETERIZED MARES INLATE-GESTATION - EFFECTS OF DIFFERENT NUTRITIONAL STATES

The effects of different nutritional states on plasma lipid concentrat ions have been examined in pregnant mares and their fetuses. Maternal and fetal arterial catheters were inserted into 12 pony mares between 244-303 days' gestation (term 320-360 days) and observations made from 5 days following the insertion of catheters. After recovery from surg ery maternal and fetal arterial samples were withdrawn from 7 mares wi th normal feeding patterns (Group IA), from four of these mares at the end of a 30 h fast and 3 h later following refeeding (Group IB) and s ix mares who failed to re-establish normal feeding patterns (Group II) . The fatty acid concentrations and composition of the plasma free fat ty acid (FFA), triacylglycerol and phospholipid fractions were analyse d. Maternal FFA, triacylglycerol and phospholipid concentrations were significantly raised in the fasted (Group IB) and under-fed (Group II) mares. Fetal concentrations of FFA and phospholipid increased signifi cantly in the group of under-fed (Group II) mares but not in the faste d (Group IB) mares. In the fetal plasma the proportions of polyunsatur ated fatty acids derived from essential fatty acids in the FFA and pho spholipid fractions were much higher than those in the mare. In the fa sted (IB) and under-fed (II) groups the relative amounts of the polyun saturated fatty acids in each fraction remained unchanged (P > 0.05). These results show a short fast or prolonged undernutrition result in raised maternal plasma lipid concentrations which in turn can effect t he total amount of lipid in the fetal circulation. However any increas es in polyunsaturated fatty acids in the fetus (e.g. in Group II) are unlikely to come from the maternal circulation; likely sources of thes e fatty acids are the placenta or fetal tissues.