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首页> 外文期刊>Polar biology >Phenotypic plasticity following weaning: winter body mass trends and food intake in relation to temperature by an arctic ungulate
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Phenotypic plasticity following weaning: winter body mass trends and food intake in relation to temperature by an arctic ungulate

机译：断奶后的表型可塑性：北极有蹄类动物的冬季体重趋势和食物摄入量与温度的关系

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Our knowledge is limited on how weaned mammals adjust to environmental events in the absence of maternal assistance in the polar north. With the expectation that weaned offspring should express the adaptive potential of the mature phenotype, we determined their appetite and body mass responses to extreme cold. Between December and May when mean daily temperature (T-a, degrees C) was between - 48 and 2.3 we provided five naturally weaned reindeer calves (Rangifer tarandus L.) ad libitum a pelleted feed of 11% crude protein with access to snow only in individual fenced outdoor pens in interior Alaska (64 degrees N 147 degrees W). We predicted voluntary food intake would meet maintenance of body mass, but that extreme cold would result in an increase in appetite that would be compensated for by access to warm water. A linear mixed effect model indicated a moderate daily increase in body mass from 55.9 +/- 1.6 kg on 9 December to 59.2 +/- 0.6 kg on 14 May and a moderate increase in intake that was evidence for maintenance of thermal homeostasis. However, at both low (<= 30) and high (>= 10) T-a (degrees C) intake increased and we estimated a lower critical temperature of - 22 and upper critical temperature at - 10 that was indicative of high total-body insulation. Despite the appetite response at low T-a, provision of warm water did not affect intake. Thus, whereas adult reindeer restrict intake by mobilization of endogenous reserves the calf thermogenic response was an increase in appetite that indicated the importance of access to a food base for calves in winter.
机译：我们的知识仅限于断奶的哺乳动物如何在极地北部没有孕产妇协助的情况下适应环境事件。期望断奶后代能够表达成熟表型的适应能力，我们确定了它们对极端寒冷的食欲和体重反应。在12月和5月之间，当日平均温度（Ta，°C）在-48和2.3之间时，我们随意提供了五只自然断奶的驯鹿犊牛（Rangifer tarandus L.）颗粒饲料，其中11％的粗蛋白只能单独进雪阿拉斯加室内（64度N 147度W）的带围栏的室外钢笔。我们预计自愿进食可以维持体重，但是极度寒冷会导致食欲增加，这可以通过获得温水来弥补。线性混合效应模型表明，体重每天适度增加，从12月9日的55.9 +/- 1.6千克增加到5月14日的59.2 +/- 0.6千克，并且摄入量的适度增加是维持热稳态的证据。但是，在低（<= 30）和高（> = 10）时，Ta（℃）的摄入量都增加了，我们估计较低的临界温度为-22，较高的临界温度为-10，这表明整体隔热性高。尽管在低T-a下食欲反应良好，但提供温水不会影响摄入量。因此，尽管成年驯鹿通过动员内源性储备来限制摄入量，但犊牛的产热反应是食欲的增加，表明在冬天获取犊牛食​​物的重要性。

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