Young B A
Can J Physiol Pharmacol. 1975 Oct;53(5):947-53. doi: 10.1139/y75-129.
The metabolic and body weight changes in two non-pregnant beef cows were studied during prolonged exposure to warm (20 +/- 3 degrees C, relative humidity 50-70%) and cold (-10 +/- 2 or -25 +/- 4 degrees C) temperatures. Other factors including daily food intake were held constant throughout each 8-week exposure. During cold exposures, metabolic rate, blood hematocrit, and plasma concentrations of glucose and free fatty acid were elevated and respiratory frequencies and skin temperatures decreased. Resting metabolic rates measured at 20 degrees C, i.e., without the direct influence of cold, were 83.4-95.3 litres 02 per hour when the cows were cold acclimated, at either -10 or -25 degrees C, and 30-40% greater than when the cows were warm acclimated. The resting metabolic response and the concomitant reduction in intensity of shivering is indicative of metabolic acclimation to cold in these animals of greater than 500 kg body weight. As well as the expected changes in body weight with changes in energy metabolism there were losses in weight (13-24 kg) during the first 3 days of each cold exposure. Weight gains occurred when the cold stress was abruptly removed. These short term weight changes were associated with changes in water intake and apparent shifts in body fluid content.
研究了两头非妊娠肉牛在长时间暴露于温暖（20±3℃，相对湿度50 - 70%）和寒冷（-10±2℃或-25±4℃）温度下的代谢和体重变化。在每次为期8周的暴露期间，包括每日食物摄入量在内的其他因素保持不变。在寒冷暴露期间，代谢率、血液红细胞压积以及葡萄糖和游离脂肪酸的血浆浓度升高，呼吸频率和皮肤温度降低。当奶牛在-10℃或-25℃冷适应后，在20℃下测量的静息代谢率，即不受寒冷直接影响时，为每小时83.4 - 95.3升氧气，比温暖适应时的奶牛高30 - 40%。静息代谢反应以及随之而来的颤抖强度降低表明体重超过500千克的这些动物对寒冷有代谢适应。除了能量代谢变化导致体重出现预期变化外，每次寒冷暴露的前3天体重都会下降（13 - 24千克）。当寒冷应激突然消除时体重增加。这些短期体重变化与水摄入量的变化以及体液含量的明显变化有关。
