Selection efficiency when using a selection index including an all-or-none trait and a normally distributed trait

TL;DR: Genetical and environmental aspects of the model, as well as problems concerning the estimation are discussed, and strong evidence seems to point out that additive-genetic difference between breeds should be used to increase milking performance.

Abstract: Parameters for crossbreedings between Bavarian Bvaunvieh and Brown-Swiss cattle are estimated. Genetical and environmental aspects of the model, as well as problems concerning the estimation are discussed in this work. Although results may be disputable, strong evidence seems to point out that additive-genetic difference between breeds should be used to increase milking performance. Heterosis-effects are found to be of minor importance. Although the generation-by-generation coadaptation of integrating gene-pools is assumed to be negligible, the estimation of recombination-loss still represents a problem. Standard-deviations of the least-squares estimates of cross-breeding-parameters are very high. Nevertheless, the use of estimable functions permits a prediction of yields according to the Brown-Swiss proportion of genes in cows.