Adaptations of glucose metabolism in multiparous sows: Effects of pregnancy and feeding level

This experiment was undertaken to determine whether pregnancy affects gluco se metabolism and insulin sensitivity in sows fed at different levels. Four replicates of six multiparous Large White sows were involved. In each repl icate, four sows were inseminated on the first postweaning estrus (pregnant group) and the two remaining were kept nonpregnant. Half of the sows of ea ch group were fed 2.5 kg/d (low level) and the others 4 kg/d (high level) o f the same standard pregnancy diet. Jugular catheters were implanted 2 to 3 d after estrus. Plasma concentrations of glucose, insulin, and FFA were de termined before and during the 4 h following the morning meal at 10, 30, 59 , 87, 93, 101, and 110 d of gestation and at equivalent periods for the non pregnant sows. Intravenous glucose tolerance tests were performed at 33, 71 , 85, 96, and 108 d by i.v. injection of 0.5 g glucose/kg BW. Compared with the glycemia before the meal, all the sows showed hyperglycemia 30 min aft er the initiation of the meal and hypoglycemia thereafter, with a minimum r eached at approximately 75 min. Insulinemia increased from 20 min after foo d access, reached a maximum at 40 min, and returned to the basal level afte r 180 min. The higher feeding level increased plasma insulin and lowered pl asma glucose levels. Glycemia and insulinemia profiles changed from 87 d on ward in the pregnant sows. The peak of glucose induced by the meal was high er, and the subsequent period of hypoglycemia almost disappeared. The area under the insulin curve was unchanged, but insulin secretion was delayed. T he glucose tolerance tests showed that between d 85 and 108 the half-life o f injected glucose increased and insulin secretion was delayed in the pregn ant sows. Compared to the following stages, plasma FFA were high before and after the meal at 10 d, which most likely was a residual effect from the p revious gestation/lactation cycle. They were lower from 30 to 101 d in the pregnant and nonpregnant sows. At 110 d, fasting FFA were high again in the pregnant sows only, very likely in relation to the preparation for lactati on. This experiment showed that insulin sensitivity decreases after 85 d of pregnancy in multiparous sows.