Studies on the energy balance in growing pigs in special reference to the effects of feeding levels and behaviour on heat production in pigs.

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A significant relationship between heart rate(HR)and heat production(HP)was obtained(r=0.81-0.95^<**->) in three feeding levels(Low, Medium and High)and under a different environmental temperature. The standing ratio per day(%)decreased with an increase in feeding level(r=-0.80^<**>). Two results of the multuple regression analysis of heat production(HP, kJ/kg^<0.75>h) on feeding level(M, divided by maintenace level ME418kJ/kg^<0.75>d), standing min (S, min/h), time lapse after feeding(T, hour)and in the morning(P=0)or in the afternoon(P=1)were as follows.(for body weight 13-15 kg)HP=11.74+6.52M+0.24S-0.33T+0.99P(R=0.85^<**>, n=288, PE=11.6%)(for body weight 38-52 kg)HP= 7.71+8.25M+0.21S-0.34T+1.16P(R=0.92^<**>, n=288 PE=10.5%)The partial coefficient of standing(S)was 0.21-0.24. Using this value, the increase of HP during 1 hour standing was calculated being 12.6-14.4 kJ/kg^<0.75>. The energy cost of standing to daily HP was 2.2-15.8 %. Each HP under the temperature of 31ﾟC, 23ﾟC and 15ﾟC was 518, 576 and 926 kJ/kg^<0.75>day, respectively. Daily HP increased significantly as environmental temperature increased. At each temperature range, the percentage of lying behaviour per day was 89, 83, 73 %, respectively. The lying time decreased with a decrease of environmental temperature. Heat production for a single penned pig was 518 kj/kg^<0.75>d. on the other hand HP for two penned pigs was 497 kJ/kg^<0.75>d at 31ﾟC. At 15ﾟC, HP for a single penned pig was 926 kJ/kg^<0.75>d, and 744 kJ/kg^<0.75>d for two penned pigs. The ratio of lying posture perday was 73 %, 81 % for a single and two penned pigs, respectively.