ASSESSMENT OF THERMOREGULATORY AND POSTPRANDIAL THERMOGENESIS OVER THE FIRST 24 HOURS AFTER BIRTH IN PIGS

Heat production was continuously measured from birth to 24 h after bir th in pigs tube-fed 14 g kg(-1) of colostrum or water (sham-fed animal s) at hourly intervals, and maintained at thermoneutrality (34 degrees C) or in moderate cold (24 degrees C). Results indicate that colostru m was necessary to initiate and sustain the postnatal rise in metaboli c rate observed at 34 degrees C. It provided about 75% of the energy r equired for heat production at 24 degrees C. Heat production was incre ased by 74% in the cold and decreased by 30% during starvation. In bot h cases, maintenance of the energy balance was achieved with a compens atory drop in body temperature. At 34 degrees C, variations in postmea l heat production represented 12% of the total 24 h energy expenditure and were almost equally due to the thermogenic effect of colostrum an d to confounding factors, including physical activity. In the cold, ca lculated postmeal thermogenesis accounted only for 3% of 24 h energy e xpenditure and for 9% of the extra heat produced in the cold. Our resu lts highlight the main role of colostral energy in the energy metaboli sm of the newborn pig in a typical birth environment (24 degrees C) an d in thermoneutral conditions (34 degrees C). Thermoneutral postmeal t hermogenesis is low and its contribution to the extra heat produced in the cold very limited.