Effects of Environmental Temperature, Humidity and Air Movement on Heat Loss Particularly that of Latent Heat, from the pig

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  • 豚の体熱放散, 特に潜熱による体熱放散に及ぼす気温, 気湿および気動の影響
  • ブタ ノ タイ ネツ ホウサン トクニ センネツ ニ ヨル タイ ネツ ホウサ

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Heat loss from 6 male castrated pigs in response to air temperature (12-33°C), air humidity (40 and 70%) and air movement (still air and 1.3 m/s air flow) was studied. Heat production, water evaporation from the respiratory tract (RWE) and skin surface (SWE), heart rate, respiration rate and rectal temperature were measured for each of these 3 factors of the environment. Heat loss was not significantly effected by environmental condition. RWE and SWE increased with temperature, the increase in RWE being greater. RWE and SWE was significantly lower by the effects of air movement at high temperature. Total water evaporation (TWE: g/kg0.75·Ehr) was estimated from the following equations (X=°C).<BR>In still air<BR>Y=-4.0865+0.9729X-0.0482 X2+0.009 X3 (R2=0.837)<BR>At an air flow rate of 1.3 m/s<BR>Y=-15.0278+2.2850 X-0.1000 X2+0.016 X3 (R2=0.734)<BR>The ratio of RWE to TWE was about 50% at 12°C and 65-75% at 33°C. The ratio of latent heat loss to total heat loss increased from 15% at 12°C to 30-50% at 33°C, and the ratio was high when there was air movement. The results obtained for heat production and water evaporation were consistent with those for heart rate, respiration rate and rectal temperature. The modes of heat loss from the pig were concluded to vary with air temperature and movement; the effects of air movement were clear at high temperature. Air movement was found to accelerate sensible heat loss and the need for heat loss as latent heat became less at high temperature. Latent heat loss was little influenced by air humidity.

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