The state of the body's immune system of beef cows with signs of endotoxicosis

Abstract

During the development of endotoxicosis of various etiologies, secondary immunodeficiency occurs in animals, which progresses due to exposure to toxic metabolites. The work aimed to study the influence of endotoxicosis on the dynamics of indicators of the immune system of beef cows. The research was conducted on the Ukrainian black and spotted dairy breed beef cows. In cows with signs of endotoxicosis, clinical signs such as swelling of the external genital organs and mammary gland, anemia of the mucous membranes, depressed state, impaired appetite, and functional disorders of the antrum and intestines were characteristic. The main immunological tests characterizing the state of the immune system of beef cows are indicators of humoral immunity (bactericidal and lysozyme activity of blood serum), cellular immunity (T- and B-lymphocytes), indicators of non-specific resistance of the organism (phagocytic activity and phagocytic index). In beef cows with clinical manifestations of endotoxicosis, inhibition of cellular, humoral, and non-specific links of the immune system was established, which led to the development of the so-called secondary immunodeficiency. This is evidenced by a decrease in the bactericidal and lysozyme activity of blood serum, a decrease in the number of T- and B-lymphocytes, and a decrease in the phagocytic index and phagocytic activity of the blood of sick cows. In particular, it was established that the lowest indicator of bactericidal and lysozyme activity was observed in the 9th month of pregnancy in the experimental group of cows, where it decreased by 15.9 and 4.91 %, respectively, compared to the control. In the above study periods, a decrease in the phagocytic activity of neutrophils by 5.04 % and the phagocytic index by 33.3 % was established compared to the indicators of the control group. During the analysis of cellular immunity, similar changes were found in determining the number of T- and B-lymphocytes; they were lower by 12.5 % and 4.19 %, respectively. Changes in the indicators of the immune system are significant and objective markers of the state of the cow's body during the development of endotoxicosis, regardless of its causes.