CROSS BREEDING EFFECTS OF DAIRY PERFORMANCE TRAITS IN CROSSING OF SLOVAKIAN PIED WITH HOLSTEIN CATTLE

Dairy performance traits (milk yield, milk fat yield and milk protein yield) of the first three lactations of 12 purebred and crossbred gene tic groups were analyzed. The genetic groups arose from crossing Slova kian Pied cattle (S) with Holstein cattle (H), The crossbreeding param eters were estimated for four submodels of the HILL-Model including ma ternal effects and for the DICKERSON-Model, The results were similar f or all traits. The additive (direct) genetic effect was most important in all lactations. In the DICKERSON-Model, the heterosis effect was l argest for all traits in the first lactation, ranging from 6 to 7% of the mid-parent value for milk yield and milk protein yield and 3% for milk fat yield. The estimates of the recombination loss were always ne gative and also reached their highest values (more than 10% of the mid -parent value) in the first lactation. In the HILL-Model, the epistati c effects were more important than the dominance effect. Comparing dif ferent types of epistatic effects the results showed that there was no reason to favour additive x additive effects at the expense of additi ve x dominance and dominance x dominance effects. The use of non-addit ive genetic effects in the genetic evaluation of cattle is recommended .