PECULIARITIES OF FORMATION OF GENEALOGICAL STRUCTURE OF UKRAINIAN BLACK-AND-WHITE DAIRY BREED IN SUMY REGION AND RESEARCH OF ITS INFLUENCE ON THE GENOTYPE OF COWS BY CAPA-CASEIN

Thanks to the breeding work carried out to create the Sumy intra-breed type of the Ukrainian Black-and-White dairy breed, it was possible to increase the level of milk productivity of animals, which today amounts to more than 6.0 thousand kg of milk. The level of milk yield is the main in the system of dairy cattle breeding. The quality indicators of dairy raw materials are also of great importance for the economy of milk production. This issue has become particularly important recently, which is associated with the negative consequences of using the Holstein breed, namely, a decrease in the level of fat and protein in milk compared to local breeds. Researchers attach great importance to the study of individual fractions of milk protein and their impact on technological qualities during its processing. Therefore, new achievements in genetics and biotechnology have been widely applied in practice. Genetic markers are even more widely used in global dairy cattle breeding. The latter allow us to identify individual genotypes at many loci and provide information about population parameters, such as alleles and genetic frequencies. Dairy cattle breeding programs in many countries around the world take into account genetic research. This is due to the possibility of rapid improvement of the quality and technological properties of milk. The effect of capa-casein genotypes on milk quality has been studied by many scientists. The capa-casein gene polymorphism has been known since 1964. By 1988, the capa-casein gene of cattle was isolated and its structure was characterized. To date, thirteen genetic variants of cattle capa-casein have been described: А, В, C, D, E, F, Н, J, I, Х, Az, A1. Genetic variants A and B are the most common, while other alleles are quite rare. The interest in this casein fraction is due to the fact that cheese from the milk of cows with the BB genotype thickens 25% faster and has a clot twice as dense as milk from cows with the AA genotype, and accordingly the yield of cheese from the milk of cows of the BB genotype is 10% higher than from the milk of cows of the AA genotype. The aim of our work was to study the features of the formation of the genealogical structure of the Ukrainian Black-and-White dairy breed in the Sumy region and its influence on the frequency of capa-casein genotypes. Materials and methods. The research was conducted at the State Enterprise "Experimental Farm of Institute of Agriculture of Northern East of National Academy of Agrarian Sciences of Ukraine" of Sumy region on the number of cows of the Ukrainian Black-and-White dairy breed (n = 23) (first group) and Sumy intra-breed type of the Ukrainian Black-and-White dairy breed (n = 40) (second group). Retrospective studies were conducted by studying the ORSEC SUMS database for the period from 1976 to 2020. The capa-casein gene polymorphism was determined in the genetic laboratory of the Institute of Physiology n. a. Bogomolets of NAS using real-time molecular biological analysis of allele recognition by polymerase chain reaction (PCR). The results obtained were processed by the method of variational statistics using the statistical 6.0 software package. The formation of an array of Sumy intra-breed type of Ukrainian Black-and-White dairy breed on the farm was started in the mid-80s of the last century. So on the breeding stock of the Lebedinian breed began to use the sperm of bulls-producers of the Holstein breed. Bulls-producers of the Holstein lines Aidial 1013415, S. T. Rokita 252803, Sowering 198998, M. Chiftein 95679, Eleweishna 1491007 and Astronaut 1458744 were involved in this process. Further formation of the genealogical structure of the herd of the Ukrainian Black-and-White dairy breed and Sumy intra-breed type had their own characteristics. Thus, in the period from 1991 to 2000, the breeding stock of animals of the Ukrainian Black-and-White dairy breed came from bulls-producers of 8 lines, while Sumy intra-breed type belonged to 13 lines. The most common lines in the first animals were – Aidial 1013415, Sowering 1989986, M. Chiftein 95679 in the second – Eleveishn 1491007, M. Chiftein 95679, Chief 1727381. The period since 2001 has been characterized by the fact that the formation of the genealogical structure of black and white herds in Sumy region was accompanied by the use of purebred bulls of the Holstein breed. The share of bulls of Ukrainian Black-and-White dairy breed was less than 10%. This contributed to the fact that the breeding stock of breeding herds belonged mainly to three Holstein lines: Chief 1427381, Eleweishna 1491007 and Starbuck 352790. We have found that the frequency of capa-casein is somewhat different in animals of different origins. Thus, animals of Sumy type were characterized with a higher frequency of both the desired homozygous BB genotype (20%) and the homozygous AA genotype (60%). A higher frequency of the heterozygous AB genotype (36%) was characteristic of animals of Ukrainian Black-and-White dairy breed. At the same time, the frequency of alleles was almost the same. There is a difference in the frequency of genotypes and alleles by capa-casein between first-born animals of different parental affiliation. Altodegri 64633889 bull daughters were characterized by a higher frequency of homozygous desired BB genotype. High frequencies of heterozygous AB genotypes were found at daughters of bull Morian 1402173979. All daughters of the bulls Detective 349159846, Maygold 534651702 were homozygous AA. The highest frequency of the BB allele was characteristic of the daughters of the bull Altadegri 64633889. Conclusions. According to the results of the study, the peculiarities of the formation of the genealogical structure of the herd of the Ukrainian Black-and-White dairy breed, which was formed according to various programs, were established. The genealogical structure at the beginning of herd formation had its own characteristics and depended on breeding directions. The period of the last twenty years in the region is characterized by the total use of Holstein Bulls on the breeding stock of the Ukrainian Black-and-White dairy breed, which explains the linear belonging of the majority of livestock to the lines of Chief 1427381, Eleveishna 1491007 and Starbuck 352790. The consequence of this is a high conditional bloodline in the Holstein breed of the firstborn. According to the results of genetic research, it was established that in the herd of Ukrainian Black-and-White dairy breed the genotype of cattle by capa-casein significantly depended on the origin. Thus, Sumy type animals are characterized by a higher frequency of homozygous genotypes – 80%, while the frequency of alleles in animals of different origins is almost the same. Parental origin also had a significant effect on the genotype of animals on this basis.