Evaluation of Holstein cows by the heat shock protein gene

The work was carried out in the conditions of the agricultural enterprise of the Republic of Tatarstan on 114 cows. It was found that 28.1 % of cows have the HSP70.1 genotype "CC", 50.9 % - HSP70.1/”C-” and 21 % - HSP70.1/”-”. The frequency of the allele variant HSP701/”C” is slightly more common (0.53) than the frequency of the variant HSP70.1/”-” (0.47). Cows with genotype ”C-” have the highest milk productivity. They surpass their peers in milk yield with the genotype ”CC” by 4 %, with the genotype ”-” by 5.7 %. The relationship of daily milk yield of cows of different genotypes with the temperature-humidity index has been studied. Animals of all genetic groups reacted to the growth of the index with a decrease in milk yield. The maximum decrease of 10.8 % is observed in cows with the genotype HSP701/”-” and with the genotype HSP70.1/«CC» (8,5 %). Animals with the genotype HSP70.1/”C-” showed a decrease in milk yield by 5.1 %. Consequently, cows with a heterozygous genotype are more resistant to heat stress.