Abstract
An evaluation of the correlation between AST enzymatic activity as a marker of mitochondrial function and the concentration of thyroid hormones present in the bloodstream of Kazakh white-headed cattle is presented. It was observed that the requirement for the physiological effects of triiodothyronine in the organism diminishes from the onset to the conclusion of the first month of lactation, which is substantiated by a reduction in the hormone concentration in the blood ranging from 1.89 to 4.02 times. Conversely, the mitochondrial activity within the cells of these animals exhibits an increase of 9.21 to 35.74%, which underscores the adaptive potential of energy-producing mechanisms. This inverse relationship highlights a complex metabolic adaptation. While thyroid hormones are key metabolic regulators, the observed dynamics suggest a shift in energy substrate utilization. The rising AST activity indicates enhanced cellular respiration efficiency, possibly compensating for the lower hormonal stimulation. This ensures stable energy production for lactation demands. Further research should focus on the molecular mechanisms behind this mitochondrial compensation and its long-term impact on cattle productivity and health in the postpartum period. Understanding these processes is crucial for optimizing animal husbandry practices.