EN
The aim of this study was to compare the milk and reproductive performance of primiparous cows imported from the Netherlands (group 1, n=88) and Germany (group 2, n=42) with cows bred in Poland (group 3, n=53), managed on a large-scale farm. Milk urea concentration and somatic cell count were also compared. Cows of group 1 were characterized by having the highest milk yield (6874 kg), fat (272.9 kg) and protein (226.8 kg) in the first 305-day lactation. Cows in group 2 had an intermediate milk yield (6580 kg) and the lowest milk fat and protein contents (3.88 and 3.27%) and yields of these components (255.3 and 215.2 kg). Significant differences were confirmed between groups 1 and 3 for milk yield, and between groups 1 and 2 as well as between groups 1 and 3 for fat and protein yields (p≤0.05). Milk urea content on the first 9 test-days was lowest in group 1 and highest in group 3 (213.7 and 225.1 mg/l; p≤0.01); whereas somatic cell count was also lowest in group 1 and highest in group 2 (399 000 and 546 000 cells/ml; p≤0.01). Age at first calving was significantly (p≤0,01) lower in group 1 (790.7 days) than in groups 2 (871.7 days) and 3 (858.5 days). Calving interval was longest in group 1, and shortest in group 2 (151.6 and 113.4 days; p≤0.01). The results of this study indicate that importing Black-and-White cows from the Netherlands for their management in largescale farming conditions is justified, whereas importing such material from Germany does not guarantee a competitive effect, compared to material bred in Poland.