Influence of range of cycling temperature on the performance of growing pigs kept at an average ambient temperature of 20 or 28°C

Three trials, each involving 192 crossbred pigs, were carried out to evaluate the effects of ambient temperature of 20 and 28°C maintained constant or cycling over the day by 1.5, 3.5 or 4.5°C around 20 or 28°C, on the performance and feeding behaviour of growing-finishing pigs. Pigs initially weighed 25kg and were slaughtered at 111kg. Ambient temperature was minimal and maximal between 0500 and 0900, and between 1700 and 2100, respectively. A 12 h light schedule was adopted (0700-1900). Growth performance and feed intake were determined on all pigs throughout the trial, whereas feeding behaviour was determined on 25% of them. At an average ambient temperature of 20°C, temperature cycling has no effect on pigs’ performance (ADG=975 g/d; feed conversion ratio=2.52 kg/kg and feed consumption=2.44kg/d). Most (80%) of feed was consumed during the daytime. At 28°C, feed intake and growth rate were lowered (P