Influence of lowering temperature and live weight on the feeding behaviour of group-housed growing pigs

The individual feeding behaviour of group-housed Piétrain x Large White barrows was studied using data recorded with electronic feed dispensers equipped with an aerial in order to identify each pig. Data were collected in groups of 3 to 4 pigs studied at two stages of growth (S1 and S2), corresponding to respective average live weights of 47 and 74 kg. Photoperiod was fixed to 12 hours of light and 12 hours of darkness. For each stage of growth, room temperature varied in a cyclic way between 22 and 12 °C ; it was maintained constant over 3 or 4 days at 22, 19, 16, 14 or 12 °C, respectively. The feeding behaviour of pigs changed rapidly with temperature. Daily number of meals (11) was not affected but both meal duration (+3 min) and meal size (+47 g) increased while temperature decreased from 22 to 12 °C. This led to a linear increase of daily feed intake (+37 g/day per degree below 22 °C). From S1 to S2, number of meals decreased from 13.0 to 9.4 per day, whereas both meal duration and meal size increased (respectively from 7.6 to 9.9 min and from 182 to 302 g). The feeding behaviour of pigs was mainly diurnal and the partition between day and night (62-38 %) was neither influenced by temperature nor by stage of growth.