Comparative evaluation of adaptivity of cows of black-and-white Holstein breed of foreign and domestic breeding

Comparative data of indicators of milk productivity and age variability in black-and-white Holstein cows of foreign and domestic selection were obtained. It was found that cows of domestic breeding in terms of milk yield for the first lactation significantly (+774.5 kg) exceed their peers of selection in the USA and slightly (+15.7 kg) in the Netherlands. For the second lactation, this tendency persists and, accordingly, amounted to +251.6 kg and +8.4 kg. Subsequently, productivity indicators level out and tend to decrease with age. The influence of linear belonging to the analyzed productivity indicators has been established. The results of a comparative assessment of the milk productivity of cows bred in different countries indicate that animals of local breeding in terms of milk yield for the first two lactations slightly exceed the indicators of their peers in the Netherlands breeding, respectively, by 15.7 kg and 8.4 kg, the difference is not significant, as for cows - first-calf heifers of American selection, milk yield of first-calf heifers of local selection significantly exceeded milk yield of peers of American selection by 774.5 kg (P≤0.01). For the second lactation, this difference was slightly less and amounted to 251.6 kg (td = 1.55), the difference is close to significant. In fact, to the same extent, the cows of the first two lactations of the Dutch selection were superior to their peers of the American selection. The widespread use of the gene pool of Holstein cattle contributed to a sharp increase in the number of economic entities with milk production of herds - 8000 kg of milk and more per cow per year, respectively, a certain increase in milk production. One of the main disadvantages of using the Holstein breed is its low reproductive capacity, in this regard, in this work, we proceed from the assumption that cows with an interbody period of more than 400 days are problematic in reproduction and cannot be used in breeding work to improve the Holstein breed.