RED STEPPE COWS ADAPTIVE CAPABILITIES UNDER VARIOUS ECOLOGICAL AND TECHNOLOGICAL CONDITIONS

The aim of tte study is to determine the adaptive properties of Red Steppe cattle under different keeping systems, as well as their heat tolerance to high ambient temperatures during the grazing period of milk production. Objectives: to study the clinical and physiological status, hematological parameters, and cellular and humoral immunity of the experimental first-calf heifers; to establish the heat tolerance index of first-calf heifers during the grazing period; and to determine the reproductive capacity and milk production level of the breeding stock depending on the keeping system. The study was conducted at Nektar-Agro LLC, located in the Kabardino-Balkarian Republic. The subjects of the study were Red Steppe first-calf heifers. Three groups of first-calf heifers were formed, 25 heads each: Group I – animals that produced throughout the year at an altitude of 220 m above sea level (stall-pasture housing system, tethered during the stall period, on village pastures in the summer), Group II – year-round mountain housing on mountain pastures at an altitude of 1300 m or more above sea level, Group III – with a transhumance-mountain housing system (tethered on the plain during the stall period, driven to mountain pastures in the summer). The best adaptability was demonstrated by first-calf heifers lactated in the mountain zone, whose superiorrity over their peers in the lowland housing system amounted to 0.16 units in the adaptation coefficient (P > 0.99–0.999). The maximum superiority in the heat resistance index was demonstrated by individuals of the transhumance-mountain housing system, whose advantage over their peers in the lowland housing system amounted to 5.2 units (P > 0.999). The group of animals kept year-round occupied an intermediate position in the analyzed index, insignificantly inferior to first-calf heifers of the transhumance-mountain housing system by 2 units. In the case of stall-pasture maintenance of red steppe cattle on the plain, in contrast to distant-mountain and year-round pasture maintenance, the adaptive abilities in the summer period of exploitation are more intense, which is confirmed by the adaptation coefficient (2.35 versus 2.19 units) and the heat resistance index (83.7 versus 86.9–88.9 units). However, the reproductive performance of first-calf heifers bred on the plains and in the mountain-pasture system exceeds that of cows kept on year-round pasture. Based on the study's results, it can be concluded that stall-based housing in winter and pasture-based housing in summer on mountain pastures are more comfortable.