The relation between body temperature, metabolic rate and climatic environment in young-growing pigs

Abstract

Young growing pigs (18 kg) were housed in two climatically controlled respiration chambers and exposed to 5 different climatic environments. Per chamber 20 pigs were housed (two groups of 10 pigs). Climatic environment applied to the treatment-group in one chamber was sequentially 25/15°C + draught, 25°C, 25°C + draught, 15°C + draught and 15°C. The control-group in the other chamber was exposed to the same temperature regime, but draught was not applied. Each treatment lasted 2 days, with one day in between. The treatment 25/15°C consisted of a fluctuation in ambient temperature during 24 h (25°C during day time, 15°C during night time). With draught air velocity was increased from 0.2 m/s to 0.8 m/s and temperature of the air stream was 5 K lower than ambient temperature. Draught occurred at night during three periods of 2 h (21.00–23.00 h, 1.00–3.00 h and 5.00–7.00 h). Draughts were applied intermittently in these 2-h periods. Within such a draught period, draught was repeatedly applied on a 4 min on and 4 min off cycle. Heat production was measured during 24 h and activity was related to this. In the treatment-group two pigs had transponders implanted to measure body temperature. Results showed that heat production and activity-related heat production were increased during periods of draught. Body temperature was affected also during draught. Effects on body temperature lagged behind heat production and activity-related heat production. Moreover effects were dependent on the temperature at which the draught occurred. With constant ambient temperature and absence of draught such effects were not present. The effect of the influence of sudden changes in climatic environment on body temperature and heat production is stressed.