Modelling energy expenditure in pigs.

Abstract

AbstractIn pigs, more than 50% of the ingested energy is dissipated as heat. The heat production of animals can be measured using indirect calorimetry, which is based on the concept that heat is produced through oxidation of nutrients. A technique was developed that allows modelling the dynamics of heat production in large, open-circuit respiration chambers. The model assumes the existence of three major components of heat production: the fasting heat production (FHP), the thermic effect of feeding (TEF) and heat production due to physical activity (HPactivity). The TEF can be further divided into a short-term component (TEFST), which is due to processes such as ingestion and digestion, and a long-term component (TEFLT), which is mainly due to the metabolism of nutrients. The FHP corresponds to the asymptotic heat production after at least 1 full day of fasting. Physical activity is measured through force sensors or through measurement of the duration of standing. Three data sets, with heat production measured in group-housed piglets (26 kg), individually housed growing pigs (69 kg) and gestating sows, were used to discuss the variation in heat production. The FHP was the main component of heat production (30 to 60% of metabolizable energy (ME) intake), whereas TEFST represented a relatively constant fraction of ME intake (approximately 8%). The TEFLT was more variable, and ranged between 1 and 9% of ME intake. The HPactivity represented between 8 (piglets and growing pigs) and 20% of ME intake (gestating sows).