Summary Local breeds can serve as an important source of genetic variability in domestic animal species. This study aimed to assess the genetic diversity and population structure of Belarusian Red cattle and their differentiation from other European cattle populations based on genome‐wide SNP genotypes. Twenty pedigree‐recorded non‐closely related cows of Belarusian Red cattle were genotyped using the Illumina BovineHD BeadChip. Genotypes of 22 other European cattle breeds were included in the study for comparison. A total of 28 562 SNPs passed through the quality control checks and were selected for analysis. The Belarusian Red cattle displayed a moderate level of genetic variability (UHE = 0.341, HO = 0.368), and the highest heterozygote excess (UFIS = −0.066), among the studied breeds; this reflects the contribution of multiple breeds to their formation. The principal component analysis, FST‐based Neighbor‐Net tree and Admixture clustering, clearly distinguished the Belarusian Red cattle from the other European cattle breeds. Moreover, the presence of ancestral genomic components of Danish Red and Brown Swiss breeds were clearly visible, which agrees with the breed's history and its recent development. Our study highlights the importance of maintaining the specific genomic components, which makes a significant contribution to the global genetic diversity in the modern population of Belarusian Red cattle, allowing us to consider them a valuable national genetic resource. Our research results will be useful for the development of conservation programs for this local cattle breed.

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S u m m a r yThe association study of BLV status (carrier, non-carrier) with the level of milk productive traits in Black and White cows of different lactation periods was performed. The blood samples were derived from the whole herd including 382 cows of fist lactation period, 253 cows of second lactation period and 197 cows of third lactation period. The presence of provirus form of BLV in blood leuco-cytes was detected by nested PCR using developed system. Based on results of PCR analysis the cows received BLV + or BLV -status. The increase of the number of cows with BLV + status from 28.5 per cent of fist lactation period cows to 36.1 per cent of third lactation period cows was observed. The significantly higher BLV prevalence (+9.0…+ 21.7 per cent) in fist lactation period cows with the «mean» (within Xaverage±σ) and «high» (more than Xaverage+σ) levels of milk productive traits (milk yield, fat content, milk fat and protein yield) comparing to «low» productive cows (less than Xaverage-σ) was observed. The data analysis in aspect of different milk productive traits indicated the higher differences between the groups differed in milk fat yield (18.3-21.7 per cent, p < 0.999). The tendencies described above in the most of cases were observed in the second and third period lactations' cows. The increase of the level of most milk productive traits (milk yield, fat content, milk fat and protein yield) in cows of different genealogical lines with BLV + status comparing to BLV -status was observed.Keywords: Keywords: bovine leukemia virus, DNA diagnostics, milk productive traits.Breeding cattle for high milk production contributes to changes in animals' health (1). Higher output of milk extends the share of available energy utilized in the synthesis of milk, and thereby promotes a negative energy balance that can be restored for the expense of body reserves, which in turn, causes a partial decline of condition. Such metabolic load is peculiar to high yielding cows as specific type of metabolism associated with increased synthesis and secretion of milk; in most cases it results in metabolic stressviolation of some energetic processes related to, in particular, reproduction and health (2). Metabolic stress during lactation affects the nature of immune response, which was confirmed by K. Kimura et al. (3) who revealed differences in leukocyte patterns of Holstein cows after mastectomy and normally lactating ones. The changed immune profile of high yielding cows is seen as the cause of their susceptibility to diseases (4-9). For example, milk yield and susceptibility to mastitis are linked by the positive genetic correlation varying from 0,24 to 0,55 (5). K.L. Ingvartsen et al. (9) have detected undesirable genetic correlations between milk yield and the incidence of ketosis (0,26-0,65), ovarian cysts (0,23-0,42), mastitis (0,15-0,68), and lameness (0,24-0,48). Increased milk production is also associated with widespread occurrence of bovine leukemia virus (BLV) in dairy cattle. It was shown that Holstein cows of Cana...

Determining the purebredity of farm animals in a breeding system is of key importance for the entire livestock industry. Purebred breeding of plant breeds is designed to ensure the production of high-value improving breeding material for commercial livestock breeding. Determination of purebredity of pigs can be carried out using single nucleotide polymorphisms (SNP). The multiplexing technology today has reached a level that makes it possible to characterize tens and hundreds of thousands of polymorphic variants simultaneously for hundreds of animals in one run of the device. For the first time, using bioinformatics methods, an analysis of genome-wide projects was carried out for 264 individuals of the species Sus scrofa located in the Sequence Read Archive (NCBI-SRA). The in silico genotype was determined for 692 SNPs, of which 59 SNPs showed a significant potential for differentiation of four commercial breeds: large white (the most significant SNPs are Chr. 6: g.85845403T> G and Chr.16: g.74053569T> C), duroc (Chr. 4: g.55661608A> G, Chr. 14: g.107689091T> C and Chr. 14: g.107939105T> C), landrace (Chr. 5: g.99925204A> G, Chr. 18: g .40100481A> G and Chr. 18: g.7664624A> G) and pietrain (Chr. 13: g.136017764T> C and Chr.17: g.47595840A> G). For breeds of duroc and pietrain pigs, the accuracy of differentiation was at least 99%, for breeds of large white and landrace pigs - over 80%, however, the sensitivity indicator characterizing the percentage of false positive results of classification was slightly over 65%. Creation of models for molecularand-genetic studies of these breeds will allow for a genetic examination of their purebredity, which will contribute to an increase in their breeding value and preservation of the national gene pool.

Genotyping of individuals of 7 commercial breeds of domestic pigs was carried out: Duroc, Landrace, Belarusian Large White, Belarusian Black-and-White, Belarusian meat, Pietrain and Yorkshire for the KDM3A and DBX2 genes. The high breed-specific potential of polymorphic loci g.58335217A>G (KDM3A gene) and g.75953650G>T (DBX2 gene) for differentiation of Duroc pigs of the species Sus scrofa domesticus was confirmed. A test model for differentiation of Duroc individuals by bioinformatic assessment of a total contribution of two SNPs of the KDM3A and DBX2 genes was proposed. This test model has no analogues in the world, and its estimation accuracy and specificity are 98.76 and 99.68 %, respectively. Using PCR-RFLP, a fast and simple approach has been developed to differentiate the Duroc breed based on the proposed test model.