11.2 Heterosis

Crossbreeding is not only applied with different breeds, but also with different selection lines. This is fully exploited in commercial pig and poultry breeding. These lines are formed by pure breeding or by crossing different breeds. After the formation of the line the animals in such a selection line are selected for a limited number of breeding goal traits. After generations of selection they excel in these specific breeding goal traits. When such lines are crossed, the crossbreds not only combine the characteristics of each of the lines, but for some characteristics the performance of the crossbreds is higher than the average performance of the parent breeds due to heterosis.