Kotrbacek V., Z. Honig: Thermal Environment, Sleep and Energy Metabolism in Piglets. Acta vet. Bmo, 58, 1989: 185-195. Effects of different thermal conditions on rapid-eye-movement (REM) sleep and its influence on the level of energy metabolism in piglets are described.Heat production, respiratory quotient (RQ) and body temperature were measured in 1-to 9-d old piglets during the individual REM sleep episodes and compared with the respective values obtained in non-rapid-eye-movement (NREM) sleep. Two-hour measurements were carried out in· metabolic respiratory chambers under comfortable thermal conditions and upon exposure to cold.Thermal comfort was provided by heating the flocr to 37°C to 38 °C for 1-to 5-d old piglets and to 34°C to 36 °c for the older animals.The air temperature in the chamber ranged between 25°C and 26 0c.Exposure· to cold was produced by decreasing the floor temperature to 28 cc.Under cold exposure the total duration of REM sleep was reduced by 50 to 60 %. Both. the number of REM sleep episodes. and their duration were decreased. Heat production in REM sleep was invariably reduced. Under exposure to cold this decrease was highly significant (P < 0.01) owing to the disappearance of muscular tremor. However, concurrent decrease in body temperature, recorded in 1-to 3-d old piglets, was not significant.In the thermoneutral environment a significant (P < 0.05) decrease in heat production was observed during REM episodes occurring shortly after food intake. By depressing the postprandial thermogenesis, REM sleep contributes apparently to more effective utilization of the food energy.Lower RQ values observed in REM sleep are related to lower glucose oxidation under muscular atony. Sleep, thermal environment, oxygen consumption, RQ

Ahtaet K 0 t r b a ~ e It V., Z. H 0 n i g: REM Sltq R«luces the Postprandiall11CTt!tlSe qf Heat I+oduction In PIglet&. Acta vet. Bmo, 58, 1989:303-31}.The changes of heat production (HP) in 3 to S-day-old Large White piglets sleeping in athermoneutla1 environment .were measured over a 6O-min· period after food intake. The measurements were carried out in a group of 10 piglets fed orally and in a group of 10 tube-fed piglets. To avoid any effect of motor activity on HP, the diet was administered in the metabolic respiratory chamber to completely reposeful piglets. The quality and quantity of the administered feed was the silme for both groups.Postprandial HP in piglets fed orally SigniflCantly increased already within the first 10 minutes after feeding. This early increase was not observed in piglets fed through the tube, what showed the effect of sensory stimulation of sympathetic nervous system on the course of early postprandial HP.The postprandial HP was also affected by the character of sleep of the experimental piglets; during REM sleep the HP was regularly lower in comparison to NREM sleep. However, this differences were significant only in piglets fed orally.The mechanism of this energy-saving effect of REM sleep apparently lies in its inhibitory effect on the sympathetic nervous system stimulated by food intake. Sleep, heat production, food intaia!, RQThat heat production (HP) increases after food intake is a phenomenon known since the last century. In spite of this fact it has recently been given unprecedented attention. For example, the increased so-called regulating thennogenic effect of luxury consumption in rats and mice has often been discussed in scientific literature (R 0 t h well and S t 0 c It s 1978, 1982, 1983; T ray h urn et al; 1982; And r e w and Don n e 1982; Her v e y and T 0 bin 1983 and others). The fact that this phenomenon has not always been successfully proved suggests that there still exist other factors responsible for the level of postprandial HP. Studies dealing with the effect of the palatability of ingested food on postprandial thermogenesis drew attention to une such factor.Two same feeds were given to experimental human subjects; postprandial heat production was higher in humans given more palatable and attractive food (L e B I a n c and B ron del 1985). These authors proved the association between the thermogenic effect offood and the activation of the autonomic nervous system via the perceptions during eating. The effect of palatability of the consumed food was evident particularly in the initial phase, called cephalic phase, whereas the second phase called digestive, is related to the processes of digestion proper (D i a m 0 n d et al. 1985). In similar experiments with dogs fed orally and through an intragastric tube, D i am 0 n d and L e B I a n c (l987ab) convincingly proved the importance of catecholamines for starting the cephalic phase, and also that both branches of the autonomic nervous system are involved in postprandial thermogenesis.Our previous studies h...