Influence of low ambient temperatures on heat production and energy balance of single-housed growing pigs fed ad libitum: a comparison with group-housed pigs

The effect of ambient temperature (T; 12 to 22 degreesC) and body weight (B W; 37 to 95 kg) on metabolisable energy intake (ME) and the components of e nergy balance was studied in six individually-housed barrows kept in a resp iratory chamber. Each animal was fed ad libitum and was exposed successivel y in a cyclic manner to variable T (three days per T). The O-2 and CO2 conc entrations, feed intake and physical activity were continuously recorded an d used to calculate total heat production (HP), heat production due to phys ical activity (HPact) and the short-term thermic effect of feed (TEFst). Th e HP and its components were modelled using non-linear equations with T, BW and ME as predictors. The results were compared to predicted values from t he equations obtained in a previous experiment performed on group-housed pi gs. Data indicate that adaptations of individually-housed pigs under cold e xposure are more extreme when compared to group-housed animals, especially with respect to the marked increase of energy intake and physical activity. The contribution of HP act to HP was on average 17 and 23% at 22 and 12 de greesC, respectively. Over this temperature range, the apparent efficiency of ME utilisation increased from 0.65 to 0.81. Prediction equations obtaine d for group-housed pigs fitted the measured HP obtained for individually-ho used pigs reasonably well, which indicates that the former can be used to m odel energy utilisation irrespective of housing conditions (individual vs. group) when differences in feed intake under cold exposure are considered.