EN
Fertility and reasons for culling of 229 crossbreeds BW x HF of different gene share of HF breed in genotypes (up to 25, 25.1-50, 50, 50.1-75, 75 and more than 75%) and 71 purebred BW cows kept under similar lifelong environmental conditions were compared. It was stated that crossing of Black-and-White and Holstein-Friesian cattle causes a desired diminution of age at the first calving in the crossbred cows of FI and F2 generations (50 and 75 % genes of HF breed in the genotype). While increasing the HF gene percentage in genotypes, a diminution of the fertility of crossbreeds and their greater culling caused by infertility should be taken into account.