Biological and selection factors of increasing the quality of the genotype based on the genetic assessment of Ayrshire bulls

The article deals with the problem of genetic evaluation of Ayrshire population and its breeders’ usage on the territory of the Russian Federation and separate regions. The annual phenotypic progress in the milk yield in all Russian Ayrshire herds (+191 kg of milk, with an average of 6 554 kg of milk with 4,08 % fat) and in breeding farms (+161 kg of milk and +0,08 % of fat) was noted. High competitiveness of the breed was proven. By the average index the Ayrshire breed surpassed other breeds by 309 kg of milk and by 0,21 % of fat. The genetic evaluation of producers is actively introduced. During the last 5 years, from 48 to 73 bulls were annually evaluated; their average breeding value (BV) ranged from +4 to +50 kg of milk. The effectiveness of evaluation and the rate of improvement in the quality of producers’ genotypes depend on many factors - the number of daughters, types of herds and regions in which they are tested. It also depends upon repeatability of test results and genetic structure of the breeding stock. The prognosis of the actual BV according to the pedigree is shown on the example of 220 bulls (r = + 0,175; P