Birth is associated with dramatic changes in nutrient supply and environmental conditions, and survival of the newborn animal is highly related to its ability to withstand stress and to develop quickly major physiological functions such as nutrition and thermoregulation. In pigs, susceptibility to hypothermia and to hypoglycemia are usually reported as major factors involved in neonatal mortality. Low energy stores, lack of brown fat and poor insulation largely contribute to the limited thermoregulatory response of the newborn pig but thermogenic capacities are developping quickly over the first 48 hours of life. Postnatal hypoglycemia is mainly due to the impairment of gluconeogenesis during the first hours of life in starved piglets (Pegorier et al.,1985) in relation with the low ability of the piglets for hepatic fatty acid oxidation.