GENEALOGICAL STRUCTURE OF THE UKRAINIAN BROWN DAIRY BREED

Improvement of the productive characteristics of the Ukrainian Brown dairy breed, namely the increase in milk yields, improvement of the quality characteristics of milk and dairy livestock, is possible due to the expansion of its breeding base and enhancement of the genealogical structure. The long-term formation of the genealogical structure of the breed made it possible to form a significant number of genealogical lines, the founders of which were mainly stud bulls of the Swiss breed. At the time of testing the new selection achievement, the Ukrainian Brown dairy breed, its genealogical structure was represented by 9 genealogical lines, such as Elehanta 148551 (29.4%), Stretcha 143612 (23.8%), Distinkshna 159523 (16.8%), Balcona 1799 (1.4%), Maketa 4307 (0.9%), Mastera 106902 (0.4%), and Laka 964 (0.2%). For the last decade, the number of stud bulls of each separate line has been gradually changing. In recent years, breeders have started paying more attention to using in the selection process the evaluation of animals by genes that associate with milk quality indicators (kappa-casein and beta-casein). Scientists develop and recommend methods for improving the genealogical structure of the Ukrainian Brown dairy breed on a regular base. Among the main ones are the following: further breeding of dairy cattle by the open population method; constant and systematic monitoring of the quality of stud bulls in the world Swiss breed gene pool within countries and lines; increasing of the efficiency of breeding by lines, and it is desirable to optimize their 5-6 structural units within one farm. It is necessary to develop a program that includes measures aimed at selecting animals with high indicators of milk productivity with an emphasis on the increased content of fat and protein in milk and on the further improvement of the exterior type. The goal of the research was to study the modern genealogical structure of the Ukrainian Brown dairy breed. Materials and methods. The research was carried out on two stud farms breeding the Ukrainian Brown dairy breed (Experimental Farm State-Owned Enterprise of the Institute of Agriculture in the North East of the National Academy of Agrarian Sciences in Sumy District and Maiak Additional Liability Company in Okhtyrka District) by analyzing the database of OPSEK Dairy Cattle Management System. We also used the data of primary zoo-technical accounting of Komyshanska PAE in Okhtyrka District of Sumy Region. To study the origin of stud bulls approved for reproduction in the breeding stock in Ukraine, the data from the website of the Main Research and Production, Selection and Information Center in Animal Breeding of the Institute of Animal Breeding and Genetics of the National Academy of Sciences (http://www.animalbreedingcenter.org.ua/) and website https://www.cdn.ca were used. It was established that animals of the Ukrainian Brown dairy breed originated from five genealogical lines of the Swiss breed: Elehanta 148551 (50% share), Distinkshna 159523 (25%), Stretcha 143612 (23%), Peivena 136140 (7%) and Vihate 083352 (1%). The genealogical structure of the breed has changed significantly since the approval, as evidenced by the absence of Lailasan 131528, Laddy 125640, Orehona 086356, Destiny 118619, Eleima 110327, Suprima 124652 and Concentrata 106157, Mastera 106902, Merediana 90827, Hilla 76 lines in the animal herds, which in our opinion is associated with a significant decrease in the number of stud and commercial farms breeding this breed in Sumy Region. On each of the studied farms, the genealogical structure of the breeding stock has its own peculiarities. At the breeding plant of the Experimental Farm State-Owned Enterprise of the Institute of Agriculture in the North East of the National Academy of Agrarian Sciences, the cattle of Elehanta 148551 and Distinkshna 159523 lines prevail. On the breeding farm of Maiak Additional Liability Company most of the cattle come from stud bulls of Elehanta 148551 line. At Komyshanska PAE most of the cattle come from stud bulls of Stretcha 143612 line. The cows of Distinkshna 159523 line were distinguished by their higher milk productivity, which yielded more than 6.000 kg during the first lactation. The stud bulls that were approved for reproduction in the breeding stock in 2023, by age, were distributed as follows: older than 10 years – 13%, from five to ten years – 36%, five years – 19%, less than five years – 32%. By country of origin, most of the stud bulls used in the breeding stock mainly came from bulls born in the United States of America (60%). It was established that the bulls used in dairy herds were in 3–8 rows from the lines founders, and those approved for reproduction were in 4–9 rows. Most of the stud bulls approved for reproduction in the breeding stock in 2023 were evaluated by kappa-casein and beta-casein genotype. The share of bulls with the desired genotype according to the BB kappa-casein is 81%, AB heterozygous – 13%, AA – 6%. According to the beta-casein genotype, the proportion of desirable A2A2 homozygotes is 64%, heterozygotes – 29%, and A1A1 homozygotes – 7% Conclusions. It is established that the majority of the breeding stock comes from bulls of Elehanta 148551, Distinkshna 159523 and Stretcha 143612 lines. The inter-herd differentiation by the genealogical origin of the cattle has been revealed. A higher milk yield is characteristic of the first-borns of the Distinkshna 159523 line. The majority of stud bulls belong to the Elehanta line (20 heads). In terms of origin of bulls used in the breeding stock, a significant part (60%) was born in the USA. The degree of relationship with the founder of the line is 3–8 generations. The majority of stud bulls, approved for reproduction in the breeding stock in Ukraine in 2023, belong to the Elehanta 148551 line. By country of origin, the majority were born in Switzerland (39%) and the USA (36%). The stud bulls with a higher average breeding value come from Germany. The latter were evaluated by the kappa- and beta-casein genotype.