Most modern enterprises producing animal products actively use hormonal preparations for animals without a detailed study of their effects on the body. This study aimed to investigate the impact of hormonal preparations on the dynamics of sex hormone levels in cows. The experimental groups of cows were formed according to the principle of analogous groups of 5 animals in each. The cows in experimental group 1 were administered 5 mL of the drug “Surfagon” intramuscularly, and the cows in experimental group 2 were administered 2.5 mL of the drug “Fertagil”. The levels of follicle-stimulating hormone, progesterone and oestradiol were determined in the blood serum of cows during lactation on days 2, 6, 10, 14, 18, 22, 26 and 30. It was found that on day 2 of the study, the level of follicle-stimulating hormone in the blood serum of cows in experimental group 1 increased by 41.18% (P < 0.05), and in cows in experimental group 2, by 52.94% (P < 0.01) compared to the control. On days 26 and 30 of the study, the level of follicle-stimulating hormone in the blood serum of cows in experimental group 1 increased by 44-53% (P < 0.05), and in the blood serum of cows in experimental group 2 by 56-60% (P < 0.05). The progesterone content in the blood serum of cows in experimental group 1 remained unchanged until day 22. Then it increased by 18.22% (P < 0.01) in the experimental group 1, and by 15.42% (P < 0.05) in the blood serum of cows in experimental group 2, compared to the control. The level of oestradiol in the blood serum of cows in experimental group 1 increased by 1.79% (P < 0.01) from day 2 of the study and by 10.06% (P < 0.01) by the end of the study compared to the control group, which should contribute to better fertilisation of cows. The results obtained may be helpful for veterinary specialists and milk producers in regulating the effect of hormonal drugs on the bodies of cows and predicting the dynamics of their concentration in the blood
cattle breeding; sex hormones; hormonal background; reproductive capacity; immunoenzymatic analysis
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