Domestic and wild animals have lived and adapted to the high-altitude environments much earlier than humans, and extensive research work has been undertaken on the adaptive processes in primates. However, the migratory farming system of goat and sheep-rearing in the Himalayas is unique and different. During ascending to alpine pastures, the animals are certainly vulnerable to cold, hypoxia, and walking stresses which have not been adequately addressed scientifically. Most studies suggest that exposure to cold and hypoxia follows a sequence of physiological, biochemical, and behavioral changes. The most characteristic adaptive changes following exposure to hypoxic high-altitude environment were found to be an increase in the values of hemoglobin (Hb), hematocrit or packed cell volume (PCV), and total erythrocyte count (TEC) and a significant decline in the number of lymphocytes and neutrophils leading to leukopenia. It was also shown in human subjects that change in the hematocrit values accurately reflected as a measure of altitude adaptation. Prolonged stay at the high altitude also resulted in a significant rise in plasma cholesterol, albumin, lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase. Malate dehydrogenase level was decreased. The native mammals such as yak, Tibetan sheep, and goats are believed to adapt to very low partial pressure of oxygen by developing anatomical and physiological alterations that equip them for survival. These include large heart and lungs, high level of arterial saturation, modification of hemoglobin structure, high energy metabolism, larger lung volume, and lack of pulmonary vasoconstriction. In spite of known facts about mechanism of adaptation, question have always remained how some small ruminants like Tibetan sheep adapt to extreme cold climate in regions like Qinghai-Tibet Plateau of China which is characterized by hypoxia and very low temperature throughout the year. Scientists have marveled at the mechanism of adaptation to such challenging conditions and have turned to the genetic basis of adaptation and the role played by the genes. Whole-genome sequencing has been carried out in different domestic animal species, and various candidate genes responsible for adaptation have been identified. It was shown that rumen microbes develop a versatile and flexible role and modulate their functions according to the season. This chapter provides a comprehensive overview and new insights into the mechanism of adaptation of small ruminants to cold and hypoxia including genetic basis of adaptation and the role played by the genes. Behavioral changes included development of salt hunger (Sect. 8.3.2 of Chap. 8 ), geophagia, and changed grazing pattern. Loading the animals, their transport by road in vehicles, and long-distance walking were found to serve as stressful factors for animals and were accompanied by significant rise in plasma cortisol and plasma prolactin levels and increase in circulating neutrophils and a decline in lymphocyte resulting in increased neutrophil-to-lymphocyte ratio.

Adaptive Responses to Altitude and Walking Stress in Small Ruminants

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发表日期：

2025年

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S. P. Singh,
J. K. Malik

摘要

Domestic and wild animals have lived and adapted to the high-altitude environments much earlier than humans, and extensive research work has been undertaken on the adaptive processes in primates. However, the migratory farming system of goat and sheep-rearing in the Himalayas is unique and different. During ascending to alpine pastures, the animals are certainly vulnerable to cold, hypoxia, and walking stresses which have not been adequately addressed scientifically. Most studies suggest that exposure to cold and hypoxia follows a sequence of physiological, biochemical, and behavioral changes. The most characteristic adaptive changes following exposure to hypoxic high-altitude environment were found to be an increase in the values of hemoglobin (Hb), hematocrit or packed cell volume (PCV), and total erythrocyte count (TEC) and a significant decline in the number of lymphocytes and neutrophils leading to leukopenia. It was also shown in human subjects that change in the hematocrit values accurately reflected as a measure of altitude adaptation. Prolonged stay at the high altitude also resulted in a significant rise in plasma cholesterol, albumin, lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase. Malate dehydrogenase level was decreased. The native mammals such as yak, Tibetan sheep, and goats are believed to adapt to very low partial pressure of oxygen by developing anatomical and physiological alterations that equip them for survival. These include large heart and lungs, high level of arterial saturation, modification of hemoglobin structure, high energy metabolism, larger lung volume, and lack of pulmonary vasoconstriction. In spite of known facts about mechanism of adaptation, question have always remained how some small ruminants like Tibetan sheep adapt to extreme cold climate in regions like Qinghai-Tibet Plateau of China which is characterized by hypoxia and very low temperature throughout the year. Scientists have marveled at the mechanism of adaptation to such challenging conditions and have turned to the genetic basis of adaptation and the role played by the genes. Whole-genome sequencing has been carried out in different domestic animal species, and various candidate genes responsible for adaptation have been identified. It was shown that rumen microbes develop a versatile and flexible role and modulate their functions according to the season. This chapter provides a comprehensive overview and new insights into the mechanism of adaptation of small ruminants to cold and hypoxia including genetic basis of adaptation and the role played by the genes. Behavioral changes included development of salt hunger (Sect. 8.3.2 of Chap. 8 ), geophagia, and changed grazing pattern. Loading the animals, their transport by road in vehicles, and long-distance walking were found to serve as stressful factors for animals and were accompanied by significant rise in plasma cortisol and plasma prolactin levels and increase in circulating neutrophils and a decline in lymphocyte resulting in increased neutrophil-to-lymphocyte ratio.