Dynamics of sex hormones in cows in the period of deep pregnancy and after calving in connection with hyperbilirubinemia

Abstract

The article presents the results of comparing the level of sex hormones estradiol, progesterone and testosterone in cows with normal and elevated levels of bilirubin in the blood during deep pregnancy and immediately after calving. A study was carried out on 20 cows, which, according to the results of the concentration of bilirubin in after calving, were divided into two groups: the first group included 8 animals with an increased level of it, the second group included 12 animals with a normal content of bilirubin. It was determined that hyperbilirubinemia is accompanied by a significant increase in the level of progesterone by 45,2% and testosterone by 52,1% in the first week after calving in comparison with animals that do not have high concentrations of bilirubin in the blood. In the absence of statistically significant differences at the beginning of the observation period 15-20 days before calving, both in the concentration of bilirubin and in the content of sex steroids in the blood, 3-8 days before calving, an increase in the level of bilirubin, progesterone and testosterone in group 1 by 43,0%, 48,0% and 19,4% than in group 2. Since progesterone and testosterone are precursors of estradiol in the process of ovarian steroidogenesis, the revealed ratio of sex steroids in the studied cows may indicate, on the one hand, a violation biosynthesis of the most important estrogen estradiol in liver pathology, but on the other hand, this may be a consequence of a slowdown in the catabolism of progesterone and testosterone with the participation of hepatic microsomal enzymes and conjugation processes.