Change of amino-acid composition of yak blood, depending on the season of the year

The results of the comparative study of yak blood parameters by amino-acid composition depending on the season of the year are presented. The research was conducted in the Republic of Tuva. The object of research were adult female yaks after the fi rst or more calving. The studied animals were at the pasture in the highlands all year round. The material of the research was whole blood stabilized by heparin and yak serum. Blood was taken in spring and autumn from the jugular vein. The determination of blood biochemical parameters and the biometric processing of the results were carried out by generally accepted methods. 14 amino acids were revealed. Of these, seven are non-essential amino acids (asparagine, serine, glutamine, glycine, alanine, histidine, arginine) and seven are essential (threonine, valine, methionine, isoleucine, leucine, phenylalanine, lysine). The amino-acid content in the blood of yaks living in highlands under low partial pressure did not vary signifi cantly during the study period. The content of non-essential and essential amino acids was recorded in the ratio of 50 : 50, regardless of the season of the year. In autumn, compared to spring, serine content increased 2.43 times, asparagine –1.05 times, valine – 1.07, leucine – 1.07 times. An increase in phenylalanine in the autumn period may indicate its suffi cient content in grass eaten by yaks. Features of the interior indicators of yaks, common in the Republic of Tuva, are the result of their long year-round pasture maintenance in extreme climatic conditions of the highlands.