Promotie

Selection for pure- and crossbred performance in Charolais

Charolais is a specialized breed used for beef production. Selective breeding in Charolais is not only aimed at producing superior purebred Charolais but also to produce crossbreds between Charolais and dairy cattle breeds like Holstein or Montbeliarde. This thesis considers a number of aspects related to selection of Charolais cattle for purebred and crossbred performance. Results show that behavior and type traits measured in purebred Charolais cattle are heritable and therefore can be included in selection. Furthermore, at the genomic level sixteen regions were shown to be associated with behavior and type traits. Analysis of traits measured on crossbreds show that breeding values of Charolais bulls based the performance of (Charolais x Holstein) crossbreds are not the same as those based on (Charolais x Montbeliarde) crossbreds. If the genetic differences between crossbred types are limited, it is recommended to combine data from both crossbreds in a single reference population in order to maximize the accuracy of genomic prediction. The selection of Charolais sires to produce purebred or crossbred animals is currently based on distinct breeding programs. This thesis recommends combining both breeding programs to increase genetic gain, simplify operating organization, and reduce associated costs.