Influence of inbreeding degree on the milk yield efficiency

The Ural type of the domestic Black-and-White mottled breed of cattle features high rates of milk productivity, good suitability for industrial milking technology, but the productive longevity is 2.4–2.6 lactations only, although in the herds there are livestock of cows with a productive longevity up to 10 lactations. The decline in productive longevity is associated with deterioration of reproductive qualities of the cows. In result of the research it was found that the most resistant to long-term use in conditions of dairy complexes for industrial milk production in pedigree reproducing farms were the cows of the Siling Trajun Rokita line. Their productive period was 4.0 lactations. In other lines, the productive longevity ranged from 1.8 (Pabst Governor’s line) to 2.5 (Montvik Chieftain’s line) lactations. A low fertility rate (less than 0.95) indicates the presence of reproduction problems in the herd. The modern Holsteinized black-and-white mottled cattle, bred in Sverdlovsk region, possess high breeding qualities. The potential of their use is quite high and, despite certain problems with reproduction system, they can produce for a long time in the environmental and forage conditions of the breeding zone. 