Finding ways to ensure the Ukraine population by livestock products without resorting to imports – the main goal of most national scientific projects. Traditional selection provides small selection effect that gives the gain 1-3% per year in animals with high productivity. It can not satisfy the current needs. Improving the efficiency of animal breeding is now increasingly associated with development of DNA-technology. Search and analyze of QTL-genes and marker associated-selection are the key areas.

PCR-RFLP analysis is one of the methods of QTL-gene polymorphism determining. It characterized by high sensitivity, speed, accuracy and easy implementation. The method allows accurately identifying the genotypes of animals regardless of sex, age and physiological state, and selecting among them the most favorable for the formation of productive traits.

Primarily alleles of milk protein and hormones genes may be considered as potential markers of milk productivity.

It have been conducted the analysis of the genetic structure of herds of Ukrainian Black and White dairy cattle reproduced in farms of Skvira region, Kyiv district. 8 genes associated with milk productive traits – kappa-casein (κ-CN), beta-lactoglobulin (β-LG), growth hormone (GH), prolactin (PRL), leptin (LEP), diacylglycerol acyltransferase 1 (DGAT1), pituitary transcription factor Pit-1, STAT5A – have been studied. Method PCR-RFLP was used to identify cows genotypes on indicated genes.

The studies found that the most favorable for cheesemaking genotype BB κ-CN gene is absent in studied animals, and allelic variant B has a low frequency, which is characteristic for different breads of Black and White cattle.

For locus β-LG gene with greater frequency (0.630) it has been revealed the allelic variant A, which controls the high whey protein and total protein content in milk. While allele B associates with high casein content in milk, higher percentage of fat and better parameters of casein coagulate.

Genotype LV of growth hormone gene in many cattle breeds associated with a high fat content in milk, VV – high milk yield. The frequencies of these genotypes in studied animals are low (0.183 and 0.86, respectively). We can predict their low fatty-milk potential.

In polymorphic system of prolactin gene allelic variant G has a higher frequency (0.880), which is characteristic of most dairy cattle breeds. According to the literature data, in animals with genotype GG observe the highest milk yield and protein content than in animals with genotype AG. Therefore, favorable genotypes on prolactin locus are prevailing in cows studied.

LEP and DGAT1 genes in animalsб involved in the process of lipid metabolism, thus their specific allelic variants control the fat content in cow’s milk. So, variant B of LEP gene and variant K (lysine) of DGAT1 gene are associated with high values of this index. “Not fatty-milk” genotypes on these gene loci predominate in studied cows.

A-allele of Pit-1 gene in many cattle breeds associated with advantages for higher milk yield and milk quality. In cows under study this allelic variant is rare (frequency 0.140).

Studied animals are also characterized by a low frequency (0.105) of desired CC genotype of the STAT5A polymorphic gene system. High fat and protein content in milk of a number of cattle breeds associated with this genotype.

Thus, the distribution of genotypes and allele frequencies of QTL-gene in Ukrainian Black-and-White dairy breed reproduced in farms of Skvira region demonstrate its great similarities with other breeds of Black-and-White genealogical root. The genetic structure of the studied cattle herds in general corresponds to the structure of Ukrainian dairy breeds and is characterized by low frequencies of allelic variants B of gene kappa-casein, beta-lactoglobulin and leptin, V – growth hormone, K – diacylglycerol acyltransferase 1, A – transcription factor Pit I and C – STAT5A, which are considered more favorable for the formation of milk production traits than the alternative. Therefore, the milk production potential of studied herds is low that needs improvement of selection work with them.

Key words: molecular diagnostics, QTL-genes, Ukrainian Black-and-White cattle, genetic structure, milk productivity.