172 Feed intake level and ambient temperature affect the body temperature of pigs exposed to heat stress.

摘要

Feed intake (FI) level affects body heat production in thermo-neutral pigs; exposure of pigs to heat stress (HS) also increases body temperature (BT). However it remains unclear whether the FI level affects the heat production of HS-pigs. This study determined the effect of FI level on BT of 9 HS-pigs (46.3 ± 2.6 kg initial BW) implanted with a thermometer set to register the BT at 5-min intervals into the ileum. Pigs were divided in two groups randomly allotted to two FI treatments: HFI, 1.20 kg/d; and LFI, 0.96 kg/d, according to a two-period switch back experimental design. Pigs were fed 3-times a day (0600, 1200, and 2200 h), same amount each time, a wheat-soybean meal-crystalline Lys, Thr, and Met diet. Ambient temperature (AT) ranged from 29.0 to 35.4°C. The BT of both HFI and LFI pigs followed a similar pattern along a 24-h period, but the BT of HFI pigs was higher than that of LFI pigs (P < 0.05). Postprandial afternoon and evening BT was higher than that after the morning meal (P < 0.05). The postprandial BT increment differed between meal times and AT, but not between FI levels. The BT of HFI and LFI pigs increased up to 0.18 and 0.22°C, 0.60 and 0.61°C, and 0.24 and 0.35°C after the morning, afternoon, and evening meal, respectively, compared with the preprandial BT (P < 0.05). Apparently, the dissipation capacity of feeding-related body heat depends on the accumulated thermal load of HS-pigs before consuming their meals; presumably, the thermal load during 6-h before the morning meal (AT below 32°C) was lower than before the evening meal (AT above 32°C). In conclusion, FI level affects the postprandial BT of HS-pigs and its magnitude is larger after the evening and afternoon meals. These data suggest that HS-pigs may reduce the voluntary FI during the afternoon and evening hours.