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The research presents the findings of DNA testing of allelic polymorphism by the PCR-RFLP method of the SCD1 gene and the relationship of genotypes with the milk fatty acid composition of Holstein cows of Tatarstan population. The research was conducted among 172 Holstein cows at the Integrated Agricultural Production Centre “Stud farm named after Lenin” in Atninsky district of the Republic of Tatarstan in 2017–2018. All genotypes of the SCD1 gene were identified through the research. The milk yield test showed that the maximum content of the mass fraction of fat was in animals with the TT genotype. The significant difference between the content of the mass fraction of fat in milk in individuals by the locus of the SCD1-Fsp4H I gene was: TT to CC – 0.32 % (p < 0.05) and TT to TC – 0.40 % (p < 0.01). The results of chromatography indicate the balance of the milk fatty acid composition of cows with the TT genotype and, as a consequence, its positive effect on the human body. Cows with a homozygous TT genotype are characterized by the optimum ratio of fatty acids in milk fat. The maximum value of the oxygen desaturation index is also observed in animals with the TT genotype by the SCD1 gene.

The study presents the results obtained in DNA testing of allelic polymorphism by PCR-RFLP based methods for the leptin and stearoyl-coenzyme A desaturase genes and the interaction of their complex genotypes on the milk productivity indicators of Holstein heifers of Tatarstan population. The study was carried out among 471 Holstein cow-heifers by Integrated Agricultural Production Centre “Stud farm named after Lenin” of Atninsky district of the Republic of Tatarstan in 2016–2018. All complex LEP/SCD1 genotypes were identified through the study. The maximum frequency was observed in the combination of heterozygous genotypes LEPTCSCD1TC 149 animals (31.5 %). Milk productivity test, based on the complex genotypes LEP and SCD1, showed that a significantly high level of productivity for 305 days of lactation was 7314.4 kg, and in heifers with a complex genotype LEPTTSCD1CC was minimal (6337.4 kg) in comparison with indicators of milk yield of heifers with other complex genotypes. According to the content of the mass fraction of fat, reliably the best indicators were established in a subpopulation of animals with a complex TT/TC genotype 3.87 %. The content of the mass fraction of protein was maximal for animals with a complex CC/CC genotype.

The choice of feed for cattle should be made by assessing the nutritional value of the feed, as well as the animal's nutritional needs. Winter rye is a major crop in northern latitudes and can be used as feed for livestock. Rye grain contains a sufficient amount of protein, but its quality may not be optimal for cattle to fully digest it. Nevertheless, there are a number of methods for processing the grain that can improve its nutritional properties, including by changing the fractional composition and solubility of its proteins. This study analyzed the influence of thermal (toasting, autoclaving, steaming, extrusion) and chemical (fermentation) methods for processing winter rye grain. Toasting and extrusion led to the greatest changes in its composition. After toasting the grain, the sugar content increased 5.81 times, while the amount of soluble fractions and protein degradability decreased by 17.92% and 11.65%, respectively, in comparison to untreated grain. Extrusion processing of winter rye led to an increase in sugar, crude protein, and metabolic energy by 49.82%, 32.24%, and 22.53%, respectively. The insoluble fraction and protein non-degradability also increased by 1.22 and 1.13 times, respectively. The enzymatic treatment of rye grains led to an increase in the insoluble fraction of proteins, as well as a significant increase in the sugar content (by 5.75 times) compared to the control of untreated raw materials. The results of this study can be used to develop optimal methods for processing winter rye grain for cattle feed, taking into account the impact on the nutritional properties of the grain, the subsequent effect on animal productivity and the economic feasibility of the method. [ABSTRACT FROM AUTHOR]

The aim of our research was to study the dependence of Kholmogorsk breed dairy cows' productivity on polymorphism of kappa-casein (CSN3), betalactoglobulin (LGB), prolactin (PRL), somatotropin (GH), thyroglobulin (TG5) genes. It was found that B allele (BB genotype) of PRL gene caused maximum increase in milk production (19.7%). Maximum increase in milk productivity (15.0%, P <0.001), was found at L allele (LL genotype) of GH gene. Significant increases in the presence of A and B alleles with AA (14.3%) and BB (12.7%) genotypes of CSN3 and LGB genes were detected. The maximum increase in fat mass fraction (0.22%) in milk was found at ABL homozygous genotype of PRL gene, while significant increase of fat content was detected at C allele (CC genotype) of TG5 gene (0.15%, P <0.05). The maximum increase of protein mass fraction at B allele (BB genotype) of PRL gene (0.11%) was detected. The maximum increase in milk protein was found at B and L alleles (BB and LL genotypes) of LGB and GH genes (0.06% with P <0.01 and P <0.001, respectively). Analysis of milk energy value showed that A and B alleles and AA (2.80 MJ / kg) and BB (2.80 MJ / kg) genotypes of CSN3 gene and BB genotype of LGB (2, 82 MJ / kg) and PRL genes (2.93 MJ / kg), as well as the T allele and TT genotype for the TG5 gene (3.17 MJ / kg) are associated with this indicator. [ABSTRACT FROM AUTHOR]