Effects of maternal nutrition during gestation on viscera energy use in ruminant dams and offspring and hypothalamic neurohormone content in the offspring

The extensive use of grazing systems for ruminant livestock and the high variation in forage quality throughout the year have important impacts on production. Changes in feed quality and availability cause alteration in the nutritional and physiological status of gestating animals. Modifications of the maternal nutritional environment throughout fetal development can have an impact on later performance of the offspring. Adjustments in maternal metabolism have been correlated with an increase in maternal energy use during pregnancy, and also further adjustments that occur in the dam's metabolism to provide adequate oxygen (O2), nutrients, and energy for fetal growth and maternal maintenance systems. Moreover, energy utilized by fetal visceral tissues can be altered in response to changes in maternal feed intake. Prolonged changes in maternal feed intake during early pregnancy, the time which fetal brain development is taking place, can result in up- and/or down-regulation of neurohormones which play an important role in controlling long-term energy utilization and feed intake in the offspring. We designed three different studies with the main objective to investigate how maternal nutrient restriction throughout gestation or during different periods of gestation affects visceral organ metabolism in the dam and in the fetus. Furthermore, we aimed to understand the effects of fetal growth restriction on postnatal liver and small intestine mass, energy use, and content of hypothalamic neurohormones that control feed intake and energy metabolism. Our results indicate that, maternal hepatic and jejunal mass and energy use are impacted by nutrient restriction and strategic realimentation during different stages of gestation. Similar responses are also observed in fetal visceral development, metabolism and liver energy use in postnatal life. Moreover, arginine supplementation appears to be a nutritional strategy that diminishes the possible deleterious effects in maternal and fetal visceral metabolism in response to nutrient restriction. Finally, maternal nutrient restriction throughout gestation decreased the number of cells expressing proopiomelanocortin (POMC) protein in the offspring hypothalamus, perhaps influencing energy metabolism in the offspring.