Changes in circulating fuels, pancreatic hormones and liver glycogen concentration in fasting or suckling newborn pigs.

The effect of fasting or suckling on blood glucose, circulating fuels, pancreatic hormones and liver glycogen concentration have been measured in newborn pigs during the first 48 h of life. Blood glucose concentrations fell to hypoglycaemic values after 48 h of fasting whereas for the same period of time, suckling piglets maintain a normal blood glucose. These differences are not due to hepatic glycogen mobilization, since liver is totally depleted from its high glycogen stores 24 h after birth, both in fasting and suckling piglets. Blood lactate is present at a high concentration during the first 48 h, both in fasting and suckling piglets. In contrast, blood pyruvate concentration is lower in suckling than in fasting newborn pigs. Colostrum intake leads to an increase in blood amino acid concentrations in the suckling piglets in comparison with the fasting newborn. Plasma non-esterified fatty acid levels and blood glycerol concentrations are lower in fasting piglets than in the suckling ones. In suckling newborn pigs, circulating ketone bodies are very low despite the increase in non-esterified fatty acids levels. The decrease in plasma insulin/glucagon molar ratio at birth, is due to a decrease in plasma insulin and an increase in plasma glucagon, both in fasting and suckling piglets. Plasma insulin and glucagon concentrations are higher during suckling than during fasting. The data suggest that gluconeogenesis could be impaired, in fasting newborn pigs, by a low plasma glucagon level and/or a limiting availability of non-esterified fatty acids.