Association of polymorphic types of stearoyl-coa desaturase gene (SCD1) with economically valuable traits in Russian population of Ayrshire cows

In modern animal breeding genes involved into biochemical and physiological pathways and having SNP polymorphisms in coding sequences (exon) leading to amino acid replacements in proteins, and in regulatory elements effecting transcription, are considered as promising marker genes. Significant attention is given to study of relations between polymorphisms in lipid metabolism genes such as leptin ( LEP ), thyroglobulin ( TG ), diacylglycerol O-acyltransferase 1 ( DGAT1 ) with milk and beef productivity traits in cattle. Little is known about stearoyl-CoA desaturase gene polymorphism and its associations with cattle traits, particularly in Russian populations. Enzyme stearoyl-CoA desaturase plays an important role in fatty acids metabolism. For dairy cattle fat and protein content as well as live weight and rate of weight gain which make an impact on animal puberty age are among the most important traits. In our paper polymorphism of single nucleotide substitution (SNP) rs41255693 in SCD1 gene has been revealed along with analysis of its link with economically important traits in first lactation cows ( n = 201) of Ayrshire breed belonging to JSC «PZ Novoladozhskii» of Leningrad region. SNP in rs41255693 region is located at fifth exon of SCD1 gene and characterized by amino acid Ala-Val substitution (allele C > T ) and revealed by FauI restriction endonuclease. Allele C is characterized by the presence of restriction site. High frequency of allele C (0.858) and genotype CC (0.731) has been observed in the population under study. Allele T is rare with frequency of 0.142, and TT genotype has been detected in only 3 animals (frequency 0.015). In order to evaluate animal breeding value (BV) comparison with contemporaries has been employed showing deviation of each animal productive trait from that of contemporaries. Animal BV was calculated by the following traits: milk yield for 305 and 100 lactation days, percentage of fat and protein, yield of fat and protein, weight at birth, at 10, 12 and 18 month age, live weight at first service and at first lactation. Beyond, age of first service, first calving and days open were also taken into account. Association between genotypes of SCD1 gene and such parameters as weight gain, animal development and reproductive traits (age at first service, age oat first calving and days open period) has not been established. Nevertheless, it has been demonstrated that data concerning SCD1 gene polymorphism allows for QTL (Quantitative Trait Loci) high fidelity mapping for such traits as milk fat and protein content. Cows of the population under study having CC and CT genotypes exceeded with statistical significance the cows having TT genotype in BV milk yield for 305 days (p < 0.01), BV milk yield for 100 days (p < 0,02), yield of fat, kg (p < 0.001), and yield of protein, kg (p < 0.001).