Nycthemeral variations of components of energy expenditure in maintenance fed adult sows ; importance of physical activity

Abstract

Heat production (HP, indirect calorimetry) of six Large White ovariectomized sows (mean BW : 208 kg), kept individually in metabolism cages at 24°C and fed once a day (d) at 100, 60 and 0% of their maintenance energy level and their physical activity (standing vs lying) were recorded continuously over 24 hours after a meal. Each sow was measured 8 to 10 times with 8 to 10 different diets over the 9 months experiment. Data were used to quantify the components of HP in maintenance fed sows. On average for the 6 sows, the energy cost of standing activity (240 minutes per day) was 14,9 kJ/min standing, which represents 15% of total daily HP (400 kJ/kg^0.75). Standing activity occurred only during the diurnal part of the day. Resting heat production (340 kJ/kg^0.75) originated from fasting heat production (260 kJ/kg^0.75) and the heat increment of metabolizable energy intake. This last component is affected by the chemical characteristics of the diet. The importance of each component of HP varies over the 24 hours period after a meal. Combined with literature data, our results suggest that energy requirements and performance of pregnant sows are highly dependent on environmental conditions and their behaviour.