Laboratory of Genetics and DNA Technologies

5 test systems have been developed and are being tested.

A fast and sensitive genetic test system has been developed to detect the carrier of the Schwyz haplotype (VN2) in cattle of the Kostroma breed. It was found that among the cows of the studied sample, no genetic variant of TUBD1C was found associated with early mortality of young animals from respiratory pathologies. The frequency of individuals carrying the BH2 mutation (TUBD1CT genotype) was low and amounted to 0.039, and the proportion of healthy TUBD1TT animals was high, at 0.961, which indicates a favorable distribution with a preponderance in favor of the TUBD1 gene desirable for breeding T-allele. Using the analysis of genealogical data, potential sources of the spread of the mutant TUBD1C allele, which causes the carriage of the BH2 mutation, in the Kostroma breed were identified – bulls of the brown Swiss breed Concentrate 106157, Master 106902, Meridian 90827, Hill 76059 and Jink 171606 of American breeding, as well as their descendants.

Only 12 complex genotypes out of 27 possible combinations were identified in the sample of cows. At the same time, the most common genotype was CSN2A1A2 CSN3BB BLGAB (0.246), and the most rare were CSN2A1A2CSN3AABLGAA, CSN2A2A2CSN3AABLGAA and CSN2A2A2CSN3ABBLGAB with a frequency of 0.018 for each of the variants. A comparative analysis of the dairy productivity of cows with different complex genotypes according to the CSN2/CSN3/BLG genes allowed us to attribute to the desirable genotypes A1A1 BB AB – in milk yield and fat content, A1A2 BB AB and A2A2 BB AB – in protein content. The A1A1 AA AB genotype was classified as undesirable when conducting breeding work to improve the chemical composition of milk, since in most cases there was a tendency to decrease the fat and protein content in milk from its carriers. As a result of the control cheese cooking, it was found that the highest actual yield per 10 kg of raw milk differed from cheeses from black-and-white cows with the A2A2 BB AB genotype (2.16 kg) and carriers of the A1A1 BB AB genotype of the Yaroslavl breed (1.83 kg). In the sample of Kostroma cows, the highest actual cheese yield was observed from the milk of cows A1A2 BB AB (1.76 kg).

As a result of genetic diagnostics, three combinations of alleles of the somatotropin and thyroglobulin genes were found in a sample of breeding cows of the Kostroma and black-and-white breeds of the region: LLCC, LLCT, LLTT. When analyzing the milk productivity of cows of Kostroma and black-and-white breeds of breeding farms of the Kostroma region, it was found that the most promising for breeding is the complex genotype LLCT.

In the course of the work, it was found that the ratio of DGAT1 gene genotypes in all studied populations is shifted towards AA and AK, with the predominance of the A allele over K. The polymorphism of the DGAT1 gene has a significant effect on the indicators of dairy productivity of cows. Cows with the AA genotype have the highest milk yield in all populations. The fat and protein content in milk, unlike milk yield, is positively influenced by the KK genotype.

A new method for determining polymorphic variants of the leptin gene in cattle has been developed and tested. The obtained results of DNA testing of cattle of different breeds indicate that the genotypes of polymorphisms A80V, R25C, Y7F of the leptin gene have a different effect on economically useful traits of cows.

The most often desirable BB genotype for cheese production was found among the brown Schwyz and Kostroma breeds – 0.533 and 0.556, respectively. The CSN3AA genotype prevails in bulls of black-and-white and Holstein breeds. The bulls of the Yaroslavl breed have the CSN3AB genotype (0.727). Genotyping of cows of the main bred breeds in the Kostroma region by the locus of the kappa-casein gene showed that the highest frequency of occurrence of the CSN3BB genotype was in cows of the Kostroma breed (0.844), the lowest – in the black-and-white breed (0.600), animals of the Yaroslavl breed occupied an intermediate position (0.684). The study of the chemical composition and the ratio of the components of milk selected for the control cheese cooking showed that the milk of Kostroma cows with genotypes AA and BB, as well as black-and-white breeds with genotype BB has the most optimal chemical composition for cheese production. As a result of the rennet test, it was found that the milk of cows of the Kostroma breed with the genotypes AA and BB and the black-and-white breed with the genotype BB has the best ability to form a casein clot of the quality necessary in cheese making. Cheese yield was observed to be 29.85-46.15% higher in cows of Kostroma and black-and-white breeds of the BB genotype than in others, and amounted to 1.74 and 1.52 kg, respectively. According to organoleptic indicators, cheese from milk of Kostroma cows with the BB genotype turned out to be the best.

For the first time, thanks to the use of the developed test system by PCR-RV, the diagnosis and frequency of occurrence of genotypes and alleles at the beta-casein locus in cows of black-and-white, Yaroslavl and Kostroma breeds in the conditions of the Kostroma region were carried out. For the first time, an analysis of the polymorphism of the beta-casein gene in a population of Kostroma cattle was carried out, which showed a high prevalence of the desired A2A2 genotype.

As a result of the conducted research on the topic: "Features of the allelic profile of genes associated with economically useful traits of Kostroma cattle" revealed high frequencies of occurrence of desirable alleles - A2 of the beta-casein gene and the allele B of kappa-casein among breeding bulls and cows of the Kostroma breed. In Kostroma cows, a high frequency of occurrence of the BoLA-DRB3*0902 allele variant associated with leukemia resistance and the absence of the BoLA-DRB3*1501 allele associated with a high viral load was established. Analysis of milk productivity indicators of Kostroma cows with the BoLA-DRB3*0902 allele in the genotype showed their significant superiority in milk yield over peers who did not have this allele.

In the course of the research work "Conservation and rational use of the gene pool, increasing the competitiveness of Kostroma cattle", a sensitive and fast real-time PCR test system for determining the BLAD mutation was created. No mutation was detected in breeding farms for domestic Kostroma and Yaroslavl BLAD breeds. In blood samples of the black-and-white (improved Holstein) breed, six percent of animals carrying this anomaly were identified.