Hormonal state of breeding bulls after a long winter period of operation in the conditions of the Udmurt Republic

Abstract

Relevance. The study will help to identify new perspectives in breeding; get new data about the biological processes occurring in the body of animals according to the endogenous hormones of breeding bulls. The hormonal-immunobiological relationship in the body of bulls and their adaptive ability in different climatic conditions is a very important issue today.Methods. The work was performed in a temperate continental climate with a long, snowy winter and warm summer in the conditions of the Udmurt Republic in the period from 2020 to 2021 on breeding bulls (n = 27) of modern breeding at the age of 15–69 months. The state of endogenous hormones testosterone, estradiol, thyroxine and cortisol after a long winter period was studied, depending on the age, breed and selection in the normal physiological functioning of breeding bulls. The average serum values of estradiol — 0.517 nmol/l, testosterone — 25.7 nmol/l, thyroxine — 74.7 nmol/l, cortisol — 420 nmol/l, and their cholesterol precursor at the level of 3.2 nmol/l were established in the blood of breeding bulls located in this region. It was found that, depending on age, there are differences in all the studied indicators, however, there is a reliability for thyroxine and cortisol. The concentration of cortisol by selection significantly differs in imported bulls of European selection from the Netherlands at the level of p > 0.05, which characterizes the presence of a certain stress adaptation factor in this group. In terms of variability, a significant difference between min and max indicators was noted for the concentration of testosterone, which varied between 2.4 nmol/l and 60 nmol/l, indicating the individuality of these hormones in breeding bulls in this region.Results. Based on the data obtained, the need to take these data into account when operating breeding bulls and analyzing sperm products, taking into account the concentration of these hormones, as well as the implementation of appropriate preventive measures, is revealed.