The Effect of Changes in the Complexly Defined Thermal Environment on Body and Skin Temperature and Energy Metabolism in Piglets

Abstract

The body temperature (TB) of piglets aged 1 to 25 days did not change significantly with changes in the cooling effect of the metabolic chamber from 40 to 60, 90, 120 and 150 W . m -2 as determined by the sensor of an electric dynamic katathermometer (EDK). Only in piglets aged 1 to 5 days a downward trend of TB was observed. The skin temperature (Ts) of the piglets, however, decreased significantly under these conditions up to the age of 10 days even if they were warmed from the floor 34°C warm. Heating the floor to 36 or 38 °C led to rapid rise and stabilization of TB at a level reached in thermoneutral environment even with high cooling effect of the chamber (150 and 180 W . m -2). In piglets laying on the floor heated to 40°C the TB significantly increased above this level.Heat production (HP) of the piglets aged 1 to 5 days was lowest at the cooling effect of 60 and 90 W . m-2 • It rose significantly with the cooling effect increasing to 120 and 150 W. m-2 but also with its drop to 40 W. m-2 • Piglets aged 6 to 10 days had their lowest heat production at the cooling effect of 90 and 120 W . m -2. At the cooling effect lowered to 60 W . m -2 their heat production started to rise and at 150 W . m -2 it was significantly higher.The heat production of piglets aged 11 to 15 days rose significantly only at the cooling effect of 180 W . m -2; the heat production of older animals was no more affected by the cooling effect of the chamber.In piglets resting on the floor heated to 34°C a rapid fall occurred in heat production even at high cooling effect of the chamber during their first two weeks oflife. With rising floor temperature their heat production continued to fall so that on the floor heated to 38°C it fell significantly below the level usual in thermoneutral environment. Heating of the floor to 40°C did not result in further decrease of heat production.These results indicate that in a complex thermal environment also the thermoneutral conditions become a more complex parameter requiring an adequate mode of their determination.Thermal environment, body temperature, skin temperature, cooling, thermoneutrality, energy metabolism.Calorimetric measurements in the laboratory as pointed out by Mount (1978) are usually carried out in standard environment in which the mean radiant temperature and air temperature are equal, natural (free) convection exists, the experimental animal is laying on an insulated floor and it is dry. In such environment the air temperature itself may characterize the thermal conditions. However, the environment in which the animals, including farm animals, live, is. never quite standard.

Thermal Environment, Sleep and Energy Metabolism in Piglets

“…The observations that sleep and, in association with it, the intensity of energy metabolism are markedly affected by thermal stimuli also in newborn piglets have been published in our previous reports (Kotrbacek 1984;Kotrbacek et al 1986). That this applies not only to total sleeping time but also to the pattern of sleep was evidenced by different electroencephalographs obtained in piglets sleeping in a thermoneutral environment and in the same animals sleeping in the cold.…”

“…Thermal comfort in the chamber was assured by the heated floor in the bottom of the chamber and by warming the air in the chamber by means of a water bath into which the chamber was immersed. Its conditions for 1-to 5-d old piglets were chosen in the light of our previuos observations (Kotrbacek 1984) and were as follows: surface temperature of the heated floor, 37°C to 38 °C; air temperature, 25°C to 26 °C; cooling effect of the environment as assessed by means of an electric dynamic katathermo-meter (Cesnek and Novak 1971), 150 to 170 W.m-2 . In piglets over 5 d of age the surface temperature of the heated floor of 34°C to 36 °C was enough to prqduce a thermoneutral environment.…”