THE INFLUENCE OF LIPID METABOLISM GENES AND THE AGE OF THE FIRST CALVING ON THE DAIRY PRODUCTIVITY OF TATARSTAN-TYPE COWS

. Identification of the optimal age of the first calving for cows of a particular herd allows them to be operated more efficiently for a long time. The optimal age of the first calving of cows is an indirect criterion for early prediction of dairy productivity and indicators of lifetime use of cows. In this regard, the aim of the research was to study the influence of the age of the first calving on the indicators of dairy productivity of Tatarstan-type cows with different genotypes by lipid metabolism genes (OLR1, DGAT1, LEP). The research was carried out on 79 first-class heifers of the Tatarstan type in the conditions of the agricultural company "Agrofirma Rassvet" of the Kukmorsky district of the Republic of Tatarstan. Genotypes of lipid metabolism genes in animals were determined by molecular genetic methods, namely: PCR-RFLP analysis (OLR1, DGAT1) and AS-PCR analysis (LEP). The analysis of the complex effect of the age of the first calving and the genotypes of the genes of the low-density lipoprotein receptor (OLR1), diacylglycerol-O-acyltransferase (DGAT1) and leptin (LEP) on the manifestation of milk productivity (yield, mass fraction of fat and protein in milk, milk fat and protein yield) of cows of the Tatarstan type was carried out. Studies have shown that with an increase in the age of the first calving to 24.1-26.0 months, 26.1 months and more, Tatarstan-type cows with the genotypes OLR1/AC, OLR1/CC, DGAT1/AK, DGAT1/AA, LEP/CC and LEP/CT increased milk productivity (yield, milk fat and protein). The opposite trend was typical for individuals with the LEP/TT genotype, in which the animals with the lowest age of the first calving (up to 24.0 months) had the highest milk productivity.