Influence of high ambient temperatures and physiological stage on feeding behaviour of pigs

Abstract

The increase of ambient temperature above the thermoneutral zone is associated with a decrease of performance in weaned piglets, growing-finishing pigs and lactating sows. This negative effect of warm exposure results mainly from a reduced voluntary feed intake. After a short presentation of the mechanisms implied in thermoregulation, the present paper will focus on the effects of high ambient temperatures on patterns of feeding in pigs. It will refer to an experimental program that began at the Pig research Station of INRA four years ago. The feeding behaviour is mainly diurnal whichever the ambient temperature and the physiological stage. Over the temperature range studied, the decreased daily feed intake with increased temperature results, first, from a meal size reduction whereas its frequency remains constant. However, data obtained in lactating sows indicate that a further increase in heat stress intensity induces a reduction in daily number of meals. When temperature fluctuates over the day around a comfort value, both growing-finishing pigs and lactating sows adapt their feed intake to environmental conditions and the lower feed intake during the warm periods of the day is compensated by an increased feed intake during the fresh periods. However under warmer temperatures (above thermoneutral zone), feed ingestion capacity does not allow for compensation of the additionnal decrease in feed intake
under warm conditions and performance are reduced.