Breeds of farm animals are characterized by the presence of their genetic structure, in particular, the distribution of allelic and genotypic frequencies by individual genetic and biochemical systems. The purpose of our search was to study the genetic frequencies of polymorphic loci of transferrin (TF), amylase (AM), ceruloplasmin (CR), hemoglobin (HB) and purine nucleoside phosphorylase (PN) in Simmental cattle and related breeds (Gray Ukrainian and Charolais), as well as to determine the degree of similarity between the expected loci and actual genotypes. As a result of research it was established that the genetic structure of the studied polymorphic loci of the Simmental breed was closer in animals of the Gray Ukrainian breed. In particular, at the locus of transferrin in individuals of the Gray Ukrainian breed there are alleles TF A, TF D1, TF D2 and TF E, whose genetic frequency was in the range of 0.051–0.603. The frequency of the Tf A allele in all studied breeds of cattle had a slight intergroup fluctuations (0.235–0.244), indicating their genetic similarity to this allele. At the locus of transferrin allele Tf D1 of the breed Ukrainian and Charolais were characterized by a lower frequency, however, according to the Tf D2 allele (frequency 0.603 in both breeds), they outperformed the Simmental breed by 11.7 %. The amylase locus in the studied breeds occurs with the alleles AM B and AM C, and with the allele AM A – is absent. The frequency of the AM B allele was highest in animals of the Gray Ukrainian breed, and in the AM C allele in the Charolais breed. It should be noted the high frequency of the AM B allele (0.910) in the Gray Ukrainian breed, which is due to the large number of BB homozygotes. Among the ceruloplasmin locus, the CP A allele had the highest frequency, and the CP B allele had a slightly lower frequency. In the hemoglobin locus, the frequency of HB A allele expression was the highest compared to other polymorphic systems and was in the range of 0.905–1.000. As for the HB B allele, on the contrary, the frequency of its appearance was much lower: in Simmental animals it was 0.095, in the Charolais breed it was 0.059, and in the Gray Ukrainian breed this allele was not observed. Among the alleles of purine nucleoside phosphoryls, the PN L allele was noted with a high frequency (0.697–0.846). The study of genotypes of genetic and biochemical systems of Simmental breed by loci TF, AM, SR, HB and PN shows that the locus TF, which is represented by the largest number of genotypes (10), was marked by a high degree of similarity between expected and actual genotypes with a significant difference (exception – genotype TF EE). The largest number of animals at this locus had the genotypes TF AD2, TF D1 D2 and TF D2 D2 (8 heads in each group), and the smallest – with genotypes TF AA, TF D1 D1, TF D1 E and TF D2 E (1–2 heads each). With the expected genotypes TF AF and TF EE, their real number was not detected, which indicates high heterozygosity. Amylase polymorphism is appeqred only by alleles AM B and AM C. Homozygous for allele B recorded a slightly larger number – in 23 individuals, while homozygous for allele C – only in 3 individuals, which coincides with the expected data in accordance with 21.690 and 1.690. The ceruloplasmin locus is marked by a slightly higher frequency of allele A, due to homo- (CP AA) and heterozygotes (CP AB), which appeared in 15 animals in both groups. Hemoglobin in the Simmental breed, as in most breeds of cattle, is represented mainly by allele A, and homozygotes of the BB allele are absent. Allele B is appeared in small quantities in a heterozygous state – in 4 individuals. The РN locus is appeared by two alleles (L and H), and there are no heterozygotes on the electrophoresis foregrams. There was a high frequency of the L allele of the PN locus, which is characteristic of breeds of the dairy direction of productivity. The PN H allele, which is characterized by high activity, is somewhat less common in Simmentals (only in 6 individuals). Thus, the study of genetic frequencies of the Simmental breed is necessary for the identification and early determination of the level of productivity of animals. Genetic frequencies of polymorphic loci are necessary for selection work with the breed, and can also be used in the breeding process to accelerate the rate of the breeding process. Searches of the genetic structure of the complex of genetic and biochemical systems are necessary for the research and preservation of the gene fund of local and endangered breeds of cattle.

The purposeful creation and use of highly productive animals largely depends on information laid down in their genes that control valuable economic useful features. The actual task is to identify and use marker genes that are responsible for displaying a certain sign of animals, in particular, the level of milk productivity. To create new forms of animals with a combination of high productivity and adaptability to various factors of external influences, for this purpose, for a long time in Ukraine, work was carried out to improve the Simmental cattle using the Red-Spoptted Holstein breed. It was supposed to that the increase in the number of animals with a part of the heredity of Red-Spoptted Holstein to 70–80% will allow to receive herds, which are characterized by good adaptive capacity, fat-dairy, high growth and meat qualities, as well as high milk yield. The searches were carried out on cows (pure-bred Simmentals and between ½ and ¾ in terms of the heredity of the Red-Spoptted Holstein breed), which were divided into groups with different levels of milk productivity for the first lactation (on the milk yield and content of fat in milk). The genetic structure was estimated by genetically determined polymorphism of groups of genetic-biochemical systems. Experiments were conducted on erythrocytes and blood plasma.Blood from animals was taken from a jugular vein in a heparin test tube. Polymorphism of proteins and enzymes was evaluated using a method of electrophoretic protein separation in 13% starch gel in horizontal chambers followed by histochemical staining. The obtained data testify that differences of animals on such parameters of dairy as milk yield for 305 days of the first lactation and the content of fat in milk is accompanied by unequal differentiation of their genetic structures by different genetic-biochemical systems. With the difference in milk yield, the most pronounced changes are observed with the transferrin locus, and in the analysis of groups of animals differing in the fat content of milk – by the AM-1 locus. This suggests that, based on such cases of negative correlations between these features, specific interlocal interactions may be based on different genetic and biochemical systems. It can be argued that the development of such searches may lead to the discovery of characteristic genotypes by a complex of genetic-biochemical systems, closely related to the corresponding complex of economic useful features.

Genetic investigations of cattle breeds in Western Ukraine are environmentally necessary, as well as they are the most relevant in connection with the formation of rock associations – for example Carpathian Brown. Addition to the study of genetic characteristics of different breeds to be used in agricultural production - it is an attempt to identify in the herd and genetically determined feature, which occurs most frequently. The choice of such economically valuable features determined by modern methods of agriculture research, and basically are chosen herds with such gene fond in which this feature is most typical. The genetic structure was evaluated for the genetically determined polymorphism groups of genetic and biochemical systems. Experiments were conducted on red blood cells and plasma. The blood of animals was taken from the jugular vein in a test tube with heparin. Polymorphism of proteins and enzymes was evaluated using the method of electrophoretic separation of proteins in 13% of starch gels in horizontal chambers with further histochemical staining. Each species is characterized by its own structural features of the genetic structure. According to locus of  transferrin breeds can be divided into two groups: with the dominance of allelic variant Tf A (Pintshau, Black and Spotted Holstein, Red and Spotted Holstein) and domination of variant Tf D2 (Symentals, Schwyz, Gray Ukrainian). Animals of Brown Carpathian breed have a large number of heterozygotes Tf AD2 (43%). The group of Schwyz has relatively high heterozygosity (49%). Groups of Black-Spotted and Red- Spotted Holstein are similar. When analyzing the genetic structure for the locus AM-1 can be noted the similarity of samples of animal Pintshau, Schwyz, Carpathian of brown rocks. In animals of Gray Ukrainian breed the frequency of allelic variants display of AM-1 was the highest and amounted to – 0.933. For ceruloplasmin locus significant differences were not found, except Gray Ukrainian breed animals where frequency of display of CP A was quite high and amounted to 0.733 and Simentales where is marked the high level of heterozygosity – 84%. At electrophoretic distillation of washed red blood cells of studied groups of animals were found two phenotypes of purine nucleoside phosphorylase: one is associated with high activity (H), the other with low activity (L).

The concept of «partblood» most are based on assumptions about longing action of genes that control is taken part in polygenic traits productivity and their system of uniform distribution of landed offspring. The literature describes few actual studies of genetic processes that occur in the offspring of crosses purebred animals. In this regard, the task of our study included a comparative analysis of the genetic structure of the source rocks (symentaly, grizzled red–Holstein) and their offspring landed the «share of blood» 1/2 (F1) and 3/4 (F2). Analysis of the genetic structure of all four groups of animals by polymorphic genetic and biochemical systems showed that transferrin locus for the particular animals are different from parental forms. So a group of animals with 1/2 blood (F1) display of high frequency of allelic variant Tf D2 (0,646). According to AM–1 locus in the studied groups manifestation of the highest frequency in the group of animals 1/2 halfblood (F–1) – 0.712 and this group is just as close to a group of purebred symentaliv (0.806). For purynnukleotydfosforylazy locus was found a high frequency of phenotypes at high activity in a group of purebred symentaliv (NP–H – 0,25). Cluster analysis showed that for genetic and biochemical systems group symentaliv (bedrock) form one cluster, and the Local animals (F–1 i F–2), and a group of red Holstein (parent rock) differs from them with a group black and other forms black Holstein, an independent cluster.

An analysis of the quantitative and qualitative composition of the breeding farms (breeding plants and breeding reproducers) for breeding cattle of the Ukrainian black-spotted dairy (UBSD) breed, located in the western region of Ukraine, was conducted. It was established that as of January 1, 2021, there were 156 breeding farms of the UBSD breed in Ukraine, including 75 (40.1 %) breeding farms and 81 (51.9 %) breeding breeders. In the western regions of Ukraine, the UBSD breed is bred in 61 breeding farms, which is 39.1 % of all breeding farms in the country. There are 20 farms (32.8 %) and 41 breeders (67.2 %) for breeding the UBSD breed in the western region of Ukraine. Among all breeding plants of Ukraine, 26.7 % and 50.6 % of breeding breeders are concentrated in the western region. Khmelnytskyi (15), Volyn (13), and Rivne (12) regions have the most significant number of breeding farms and the most minor – in Ivano-Frankivsk (5); there are eight breeding enterprises each in Lviv and Ternopil regions. As of 01.01.2021, the population of animals of the UBSD breed in the breeding farms of Ukraine amounted to 143864 heads (head), including 59.0 % in breeding plants and 41.0 % in breeding breeders. The population of animals of the UBSD of the western region of Ukraine totals 64220 animals, or 44.6 % of all livestock in the country. Khmelnytskyi and Volyn regions are the leaders regarding the number of UBSD breeds among the western regions of Ukraine. Ternopil and Rivne regions were less numerous, and Lviv and Ivano-Frankivsk regions had the most miniature breeding animals. Out of 61591 heads, there is 25967 head of pedigree cows of the UBSD breed, bred in farms in Ukraine, with pedigree status in the western region or 42.2 %. The most numerous were Ltd “Progres” (2469 heads), PLAE named after Ivan Franko (2086 heads), PLAE named after Shevchenko (2054 heads), Ltd “Lyshche” (2021 heads) and JPE “Rat” (1992 heads). As of January 1, 2021, there was 12167 head of cattle in the breeding farms of Ukraine, including in the western region – 5389 heads or 44.3 %. There were 22399 heifers over one-year-old in breeding farms in Ukraine, of which 9834 were in the western part or 43.9 %. A significant number of heifers older than one year were observed in the Volyn, Khmelnytskyi, and Ternopil regions. Milk productivity of UBSD cows for 305 days of the last completed lactation on all breeding farms of Ukraine was, on average, 7737 kg of milk yield, 290 kg of milk fat, and 254 kg of milk protein. In cows bred in breeding plants, the named indicators were higher than those kept in breeding breeders. Thus, the cows of breeding farms weighed 7991 kg, and the amount of milk fat and protein was 300 and 266 kg, respectively. In cows from breeding breeders, the mentioned indicators were lower than cows from breeding plants by 611, 25, and 29 kg, respectively. In breeding farms of the western region of Ukraine in all studied areas, the average weight of cows was 7019 kg, the amount of milk fat was 259 kg, and the amount of milk protein was 227 kg. The highest milk yield among enterprises in the western region of Ukraine belongs to the Volyn region – an average of 9132 kg (in breeding plants – 9413 kg; in breeding breeders – 7140 kg). High milk yield in the mentioned region was noted by the cows of the UBSD breed PLAE “Progres” (12082 kg), FE “Perlyna Turia” (11015 kg), PLAE named after Ivan Franko (9800 kilograms), Ltd “Lyshche” (9501 kg) and Ltd “Rat” (9186 kg). The milk productivity of probonitized cows of the UBSD breed for one lactation on average for all categories of breeding enterprises (14107 heads) amounted to 7563 kg of milk yield, and the amount of milk fat and milk protein was 282 and 247 kg, respectively. In the breeding farms of the western region of Ukraine, the yield averaged 7563 kg, the amount of milk fat – 241 kg, and the amount of milk protein – 219 kg. Higher productivity was observed in cows from Volyn, Ternopil, and Lviv regions, slightly lower productivity – from Khmelnytskyi and Rivne regions, and the lowest productivity – from the Ivano-Frankivsk regions. For the third lactation and older, the probonitized cows of the UBSD breeds of breeding farms of Ukraine (19011 heads) had an average yield of 7748 kg. In cows kept in enterprises of the western region of Ukraine, this indicator was 7141 kg on average. The highest milk yield was obtained from cows that belonged to the Volyn region breeding farms (9732 kg on average for the region). Among the enterprises in the Volyn region, the “Progres” dairy farm (13280 kg), the Ivan Franko dairy farm (11360 kg), the Perlyna Turia farm (11201 kg), the “Lishche” dairy farm (9814 kg) and the “Rat” dairy farm (9250 kg); in the Lviv region – Molochni Riky LLC (11125 kg); in the Rivne region – Ltd “n.a. Volovikov” (7495 kg), PAE “Ukraina” (7310 kg); in the Ternopil region – PAE AF “Horyn” (10488 kg), PAE “Agroprodservice” (10360 kg), LLC “Buchachagrokhlibprom” (9370 kg) and in the Khmelnytsky region – PE “Agrarna Compania 2004” (7402 kg). The distribution of UBSD breed cows by milk yield for 305 days of the highest lactation showed that 5019 cows with a milk yield of 10001 kg and more are kept in breeding farms in Ukraine; with a milk yield of 9001–10000 kg – 5788 heads and with a milk yield of 8001–9000 kg – 2969 heads. In the regions of the western region of Ukraine, these indicators were 2006, respectively, 1991, and 2027 heads. The reproductive capacity of animals is closely related to their productive qualities.