110 BARLEY SUPPLEMENTATION AT MID-GESTATION IN BROODMARES DOES NOT AFFECT FETAL DEVELOPMENT AND IS ACCOMPANIED BY MINIMAL PLACENTAL ADAPTATIONS

Abstract

Modifications of maternal environment could alter fetal growth and development through the placenta and thus health in adulthood. The developmental origins of health and disease suggest that maternal nutrition during pregnancy may affect offspring development and subsequent energy metabolism. To understand the effect of common feeding practices during gestation, 24 saddlebred mares were allocated to 1 of 2 groups: group B was supplemented twice a day with barley (B) and group F was fed only with fodder (F) between month 7 of gestation and foaling. B mares maintained an optimal body condition score through gestation, with an increase in glycaemia and insulinemia after each meal and insulin resistance in month 9 of gestation. F mares lost condition as assessed by body condition score in the last part of gestation, leading to a moderate undernutrition and a transitional increase in nonesterified fatty acid plasma concentrations. Diets had no effect on feto-placental biometry or on placental structure. In contrast, an increase in microcotyledonary vessel volume was observed in F placentas, indicating placental adaptation, possibly to increase fetomaternal exchanges. There was no overall difference in the expression of genes involved in vascularization, nutrient transfer, growth, and development between placentas from B and F mares. Nevertheless, as seen in other species, sex-specific effects of maternal nutrition were observed in placentas from female foals, with differences in the expression of endogline, kinase insert domain receptor, insulin-like growth factor 2 and insulin-like growth factor 1 receptor genes. This study demonstrates that breeding practices such as supplementation in concentrate at mid-gestation do not seem to affect fetal development. More work is ongoing to evaluate postnatal health.