The author has carried out a comparative analysis of productive qualities of two populations of Ayrshire cattle in the Leningrad Oblast and the Republic of Karelia. For the analysis, we used data from the yearbooks of All-Russian Research Institute of Pedigree Breeding for 2010–2019 and electronic databases “Selecs” for 2020. The article has found that the cows of breeding farms of Leningrad population are inferior to the group of animals from Karelian population in milk yield of 410 kg. On the contrary, in breeding reproducers, they exceed them by 494 kg of a higher protein-milk content (+0.06 and +0.13%, respectively) and low fat content of milk (-0.08 and -0.19%, respectively). The paper reveals a high level of genetic trend in milk yield (+22 kg of milk) in Karelian population with genetic improvement rate +0.34 and lower indicators (+4 kg and 0.06) in Leningrad population. We selected 228 cows in Leningrad and 81 in Karelian populations that completed 1–3 lactation with milk yield exceeding 11,000 kg of milk, 102 and 32 heads with a fat and protein content of more than 4.00 and 3.20%, respectively, as potential mothers of new generation bulls. In Leningrad population, 45.6%, and in Karelian 36.4% of first-calf heifers have fathers with breeding value for milk yield of +100 or more kg of milk, and 32.9 and 27.8%, respectively, are assigned to the best class by pedigree. The low value of genetic similarity in male ancestors of three lines of the first-calf pedigree in the studied populations indicates the regional specifics of the bovine population which determine the differences in economically useful characteristics of animals in regional populations. On the one hand, the revealed diversity in Ayrshire breed will help to maintain effective selection; on the other hand, it indicates its heterogeneity which weakens the genetic progress in the breed
Keywords
ayrshire breed, Ayrshire breed, regional population, genetic trend, genetic similarity