Hormonal panel of various breeds of cattle under the conditions of temperature stress

Abstract

The article gives the data on the content of a number of steroid and thyroid hormones in the population of Tagil, Suksun and Holstein cattle under the conditions of increasing environmental temperature resulting in moderate stress reaction, as well as on the changes in endocrine system after temperature stress. Changes in function of vascular glands were found showing high resistance of Tagil cattle, moderate resistance of Suksun cattle and low resistance of Holstein cattle to temperature stress. The most significant changes were noted in thyroid panel of Tagil cattle that was shown by increasing synthesis of iodothyronine while environmental temperature changed from high to normal values (during post-stress period). The breeds with lower resistance had the signs of deterioration of adaption mechanism expressed in stronger unbalance reaction of hormonal axis.