A detailed evaluation of reproductive usefulness was carried out on 187 bulls (82 Black-and-White bulls, 58 R₁ — 25% hf hybrids and 47 F₁ — 50% hf hybrids). Moreover, the analysis of 3002 (BW-1319, 25% hf — 462, 50% hf — 571, 75% hf — 488 and more than 75% hf — 162) bulls was carried out pertaining to the final evaluation of reproductive usefulness (class A, C, D). The objective of the research was to establish the correlation between detailed and final evaluation of the reproductive usefulness of young bulls reared in testing stations and their genotype. The body weight on day 360, daily body weight gains and energy consumption per 1 kg of body weight were found to be correlated with the volume of ejaculate (resp., r = 0,28, 0,33, — 0,32), libido (resp., r = 0,30, —0,33, 0,34). general evaluation of reproductive usefulness (resp., r = 0,34, 0,23, — 0,09) and breeding evaluation (resp., r = 0,59, 0,44, — 0,09). In the final evaluation of reproductive usefulness the worst results were obtained for 25% hf genotype bulls (black crossing — 47% bulls in class A), the best for F₁ 50% hf hybrid bulls (56% in class A), which confirmed the principle that within low heredity reproductive traits heterosy occurred in F₁ generation, and depression (bac crossing) in R₁ generation.
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