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 genetic groups were analyzed. The genetic groups arose from crossing Slovakian Pied cattle (S) with Holstein cattle (H), The crossbreeding parameters were estimated for four submodels of the HILL-Model including maternal effects and for the DICKERSON-Model, The results were similar for all traits. The additive (direct) genetic effect was most important in all lactations. In the DICKERSON-Model, the heterosis effect was largest 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 negative and also reached their highest values (more than 10% of the mid-parent value) in the first lactation. In the HILL-Model, the epistatic effects were more important than the dominance effect. Comparing different types of epistatic effects the results showed that there was no reason to favour additive x additive effects at the expense of additive x dominance and dominance x dominance effects. The use of non-additive genetic effects in the genetic evaluation of cattle is recommended.