Variability of dairy productivity of cows depending on the breeding method by lines
The effectiveness of intraline and interline selection at breeding of Sumy intrabreed type of Ukrainian Black-and-White dairy breed were carried out in the breeding farms of Pidlisnivskoyi branch of PJSC “Raise-Maximko” and “Pershe Travnya” in the Sumy district. According to the results of researches of cows of Ukrainian Black-and-White Dairy breed, regularities of influence on the level of traits of dairy productivity of different variants of selection were determined and confirmed by statistical reliability. According to the evaluation of cows under control herds obtained during intra-linear and interlinear selections, it was found that most often among the evaluated variants the offspring obtained from interlinear crosses were the best on the grounds of milk productivity. In the herd of breeding farm “Pershe Travnya” sires of Starbak's parental line 352790 were successfully combined in all investigated variants of interlinear crosses with maternal Eleveyshna 1491007, Valianta 1650414, S.T. Rokita 252803 and P.F.A. Chifa 1427381, as evidenced by the high milk yield of cows, received from these combinations, which was according to the first lactation 5837-6223 kg of milk and higher - 6525-7474 kg. The difference in milk yield of first-born cows obtained in the interlinear crosses with Starbak's parent line 352790 ranged from 404 (P <0.05) to 790 kg (P <0.001). In the system of linear breeding the reasonableness of carrying out regular monitoring to evaluate the combination of lines in the breeding process of dairy breeds is motivated. Reapplication of the most successful and abandonment of ineffective selection options will help to increase the genetic potential of dairy productivity of cattle produced by Ukrainian breeds.