Changes of biochemical indexes of blood of high-performance cows are at subclinical ketosisand its effect on milk productivity

Abstract

The article provides data on changes in biochemical indicators of blood serum of high-yielding cows under conditions of subclinical ketosis and its effect on milk's physical and chemical composition. The decrease in glucose and insulin concentrations mediates the main metabolic changes necessary to stabilize blood glucose levels, which include an increase in the rate of gluconeogenesis, a decrease in lipogenesis and an increase in the release of nonesterified fatty acids from fat, an increase in the uptake and metabolism of fatty acids in hepatocyte mitochondria, and excessive formation of ketone bodies. Fatty acids and ketone bodies are used as an alternative source of energy in the heart, kidney, skeletal muscle, and mammary glands to conserve glucose further and restore energy balance. However, cows that do not undergo the necessary metabolic adaptations are susceptible to hyperketonemia. Hypoglycemia, increased activity of enzymes, and increased activity of alanine and aspartate aminotransferases were detected in sick animals by two and three times, respectively, compared to healthy animals. The total bilirubin content in sick cows' blood serum increased three times compared to the indicators of healthy animals. An increase in milk fat (up to 5 %), 1.3 times more than in healthy animals, and a decrease in total protein (up to 3.11 %). The number of somatic cells in the average milk sample of sick animals was 349 thousand/cm3 and 90 thousand/cm3 in healthy ones, which significantly worsens milk quality. The increase in the number of somatic cells in the milk of animals suffering from subclinical ketosis is due to a decrease in both the general resistance of the body and the ability of macrophages to phagocytosis; with ketonemia, a significant amount of histamine is formed, which leads to inflammatory processes of the mammary gland; the ability of leukocytes to migrate to the foci of inflammation decreases, which determines the protracted course of the disease.