The purpose of this search was to investigate the influence of “Thireomagnile” and “Thyrioton” on the antioxidant status of cows in the development of endotoxicosis. The experimental part of the work was performed at the Department of Pharmacology and Toxicology of Stepan Gzhytskyj Lviv National University of Veterinary Medicine and Biotechnologies, in the laboratory of Pharmacology and Toxicology of the State Scientific Research Institute of Veterinary Preparation and Feed Additives (Lviv) and in the Ltd. “Barkom”, village Yampil of Pustomyty district, Lviv region. To solve the tasks of the research, three experimental groups of 10 pregnant cows of the Ukrainian Black-Spotted Dairy breed were formed in each: control and two experimental. Cows of the control group (K) had characteristic clinical signs of endotoxicosis. Animals of the first experimental group (E1) were given 10 mL per animal of “Thyroid magnet” at the eighth and ninth months of gestation. The animals of the second experimental group (E2) were given Thyrioton at a dose of 10 mL per animal in the eighth and ninth months of gestation. As a result of the conducted researches it is found out that in pregnant cows with clinical manifestation of endotoxicosis the inhibition of the activity of the antioxidant protection system and intensification of processes of lipid peroxidation occurs. The use of “Thireomagnile” and “Thyrioton” in cows by the development of endotoxicosis contributed to the increased activity of the antioxidant system, which is indicated by an increase in the activity of glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase. The use of of “Thireomagnile” and “Thyrioton” to cows in the development of endotoxicosis contributed to the suppression of lipid peroxidation processes, which is indicated by the low level of primary and final products of lipid peroxidation, namely: lipid hydroperoxides and TBA-active products. Better normalizing action on the equilibrium on the activity of the antioxidant system and the intensity of lipid peroxidation was shown by the introduction of “Thyroid magnet” at a dose of 10 cm3 per animal.

The notion “endotoxin” is conditional, for any normal metabolit has a toxic impact of its excessive accumulation in organism. Endotoxins include products of breakdown of tissue proteins, peroxides and other products of free radical oxidation, low molecular weight toxins, toxins of microorganisms. Current knowledge on the mechanism of endotoxin action on the organism of pregnant cows is based on the key role of the immune system: it provides animals with protection against the infections, eliminates extraneous elements of endogenous and exogenous origin. It is defined that under endogenous intoxication, toxic metabolites suppress the activity of immune system of organism, decreases the resistability of an organism to negative effects of environmental factors. Animals under endogenous intoxication had the following clinical symptoms: swelling of mammal gland, edemas of external genitals, anemia of mucous membranes, functional disorders of proventriculuses and intestines, animals were stressed. It was defined that under endogenous intoxication in 8–9 months of pregnancy, blood of highly-productive cows had a tendency of decrease in the number of erythrocytes by 21.0%, in the level of hemoglobin – by 24.3%, increase in the number of leucocytes by 7.6% compared to the value for blood of cows with physiological pregnancy process. The development of endogenous intoxication among pregnant cows causes disorders in protein-synthesizing function of liver, which is indicated by decrease in the level of total protein and its fractions. It was defined that endogenous intoxication decreased the content of total protein in blood by 18.4%. Over the period of study, among pregnant cows under the development of endogenous intoxication, heightened activity of amino transferaces in the blood was observed. In the ninth month of pregnancy, the activity of amino transferaces in blood serum of cows from experimental group increased by 28.6%, and the activity of aspartate aminotransferace increased by 20.1% relatively. The activity of amino transferaces and decrease in the level of total protein and its fractions in blood serum is one of the first biochemical studies on the diagnosing endotoxin manifestations and indicates destructive processes in liver. It was defined that pregnant cows under the development of endogenous intoxication suffer disorders in detoxicating function of liver and disorders in filtrating function of kidneys. The developing endogenous intoxication of pregnant cows suppresses the activity of enzymes in their glutathione system of antioxidant protection, which is indicated by decrease in the activity of glutathione peroxidase by 27.5 %, glutathione reductase by 42.9%, glucose-6-phosphate dehydrogenase by 11.2% in blood serum. The lowest activity of enzymes of glutathione system in blood of highly-productive cows under endogenous intoxication was observed in their ninth month of pregnancy, which is related to increase in activation of processes of lipid peroxidation and misbalance between the activity of antioxidant system and intensity of lipid peroxidation. Reliable increase in the content of lipid hydroperoxides by 70.9% and in concentration of malondialdehide by 54.8% was observed. Misbalance towards generation of active forms of oxygen and their metabolites, exhaustion of antioxidant system and disorders in balance cause oxidative stress.