Maloiy G M O, Kanui T I, Towett P K, Wambugu S N, Miaron J O, Wanyoike M M
Comparative and Integrative Physiology Laboratory, Department of Veterinary Anatomy and Physiology, University of Nairobi, P. O. Box 30197 00100, Nairobi, Kenya.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Oct;151(2):185-90. doi: 10.1016/j.cbpa.2008.06.019. Epub 2008 Jun 25.
Comparative investigations were made between wild and domestic ruminants from arid and semi-arid regions and those species from non-arid areas in an attempt to evaluate the adaptations of these ruminants in terms of the effects of heat stress and dehydration on food intake and digestibility. The effect of (a) an intermittent heat load (a daily light cycle of 12 h at 22 degrees C and 12 h at 40 degrees C) compared to 22 degrees C throughout the day and (b) dehydration level of 15% weight loss, with and without the heat load, on the intake and digestibility of a poor quality hay was investigated in the Grant's gazelle, Oryx, the domestic Turkana goats, fat-tailed sheep, zebu cattle, Thomson's gazelle and wildebeest. The intermittent heat load with water available ad libitum depressed the food intake of zebu cattle and Turkana goats by more than 40%. It had no significant effect on the food intake of the other species. The Thomson's and Grants gazelle, oryx, wildebeest and fat-tailed sheep appear well adapted to withstanding a periodic heat load. Dehydration at 22 degrees C caused a marked depression on food intake of all the species investigated. Dehydration together with a heat load caused no further reduction in the food intake by the Grants's gazelle, oryx, and goats but it did cause a further reduction in the intake in the other species. The small non-domestic ruminants (i.e. Grant's and Thomson's gazelle) appear much more digestive efficient than any of their domestic counterpart.
对来自干旱和半干旱地区的野生和家养反刍动物与来自非干旱地区的反刍动物进行了比较研究，旨在根据热应激和脱水对食物摄入量及消化率的影响来评估这些反刍动物的适应性。研究了以下两种情况对格兰特瞪羚、东非直角长角羚、家养图尔卡纳山羊、肥尾羊、瘤牛、汤氏瞪羚和角马食用劣质干草的摄入量和消化率的影响：(a) 间歇性热负荷（每日12小时22摄氏度光照周期和12小时40摄氏度光照周期）与全天22摄氏度相比；(b) 体重减轻15%的脱水水平，有或无热负荷。随意饮水条件下的间歇性热负荷使瘤牛和图尔卡纳山羊的食物摄入量降低了40%以上。对其他物种的食物摄入量没有显著影响。汤氏瞪羚、格兰特瞪羚、东非直角长角羚、角马和肥尾羊似乎很适应承受周期性热负荷。22摄氏度时的脱水导致所有被研究物种的食物摄入量显著下降。脱水加上热负荷并没有使格兰特瞪羚、东非直角长角羚和山羊的食物摄入量进一步降低，但确实导致其他物种的摄入量进一步减少。小型非家养反刍动物（即格兰特瞪羚和汤氏瞪羚）的消化效率似乎比它们的家养同类要高得多。
