The influence of technological stress on the immunological reactivity of first-calf heifers, taking into account metabolic indices

The aim of the study was to evaluate the effect of technological stress on the immunological reactivity of first-calf heifers of the Ukrainian Red dairy breed, taking into account metabolic indices. The studies were conducted in the third month of lactation. The index assessment was carried out by calculating the ratios of metabolic parameters: (albumin and globulin (ALB/GLOB), aminotransferases (AST/ALT), glucose and albumin (GAR)) and immunological parameters (CD3/4, CD3/8, CD4/8, CD3/25). Technological stress induces maximum tension in the mechanisms of the ratio of T-helper lymphocytes to T-suppressor lymphocytes, and T-lymphocyte activation in first-calf heifers. The most stable indicator is the ratio of the total number of T-lymphocytes to T-helper lymphocytes. In the examined first-calf heifers, the albumin-to-globulin ratio corresponded to reference intervals, indicating a relatively high level of adaptability, which is genetically determined. The compliance of the obtained AST and ALT ratios with reference intervals confirms the cows' relatively high functional capacity. The glucose-to-albumin ratio in the examined cows is highly dependent on external factors and requires maximum attention to the intake and absorption of these substances. The results show that the sensitivity of first-calf heifers to technological stressors is associated with both immune and metabolic processes. In animals of the Ukrainian Red dairy breed used, adaptation to these natural, climatic, and technological conditions occurs primarily at the phenotypic level, under conditions of high external influence. The first-calf heifers experience stress in both individual components of the immune system and the metabolic system.