Physiological Basis of Adaptation of Yakut Horses to Subarctic Climate

Abstract

The Yakut horse is the northernmost horse on the planet and indeed the most resistant to cold. Local horses are well adapted to extreme environmental conditions, wherein in winter, the air temperature reaches record low values (especially at night) and ranges from ‐59.8 to ‐64.4°C. Despite such extreme conditions, Yakut horses are outdoors all year round, thanks to their compact body structure, thick coat, and the thick layer of subcutaneous fat. In this regard, the study of the mechanisms of survival of local horses to extremely cold environmental conditions is of particular scientific and practical interest. The work aimed to study the mechanisms of physiological adaptation of the Yakut horse to extreme environmental conditions during the cold season. The work was carried out at the Department of Physiology of Farm Animals and Ecology of the Arctic State Agrotechnological University. In Yakut horses in the cold season, the total protein content in the blood is significantly higher by 25.19% than in spring (P<0.001). Reliably high rates are noted for protein fractions: α1‐globulin by 29.95% (P<0.05), β‐globulin by 16.69%, and γ1,2‐globulins by 42.29 and 40.2% (P<0.05 0.001), respectively, compared with those in the spring. At the same time, the activity of enzymes and substrates in the blood serum (AsAT, ALT, and Alk‐Phos) of the studied horses is within the physiological norm. In spring, we note a decrease in the level of total protein in the blood against the background of a decrease in globulins by 29.4%, which is most likely due to the late pregnancy period in mares. The content of albumin in the blood serum in the spring decreases by almost 3%, while the albumin‐globulin coefficient increases by 0.09 units, indicating a more intense course of protein metabolism in animals during this period. Thus, in the cold period, the activity of the immune system in Yakut horses is significantly higher than in spring, which provides high adaptive qualities of animals to shallow air temperatures with poor pasture. In the spring, the Yakut horses have an increase in protein metabolism, which coincides with the physiological state of the mares, caused by an increase in the energy and plastic needs of the fetus.