Including fertility performance in the estimation of breeding values in pigs - 2nd communication: Purebred and crossbred performances

The main objective of this study was to investigate the genetic relation be tween purebred and crossbred fertility performance. For the estimation of t hese genetic correlations, multiple trait animal models have been used. Altogether 7 531 litters of German Large White sows and 2 944 litters of cr ossbred sows have been analysed. The crossbred sows where descendants of bo ars from German Large White and sows from German Landrace. The genetic rela tions have been mainly realized by 64 boars having descendants in both pure bred and crossbred. Due to the lack of enough data it was not possible to get reliable paramete r estimates for the modified repeatability model with the first litter cons idered as a separate trait (see Ist communication). Using the pure repeatability model the estimates for the genetic correlatio n has been between 0.5 and 0.7, which is significantly different from 1. Us ing purebred and crossbred performance together is therefore for the invest igated populations not permitted. To use the advantages of investigating pu rebred and crossbred performance at the same time they have to be considere d separately. The use of information from crossbred progenies increases especially the ac curacy of the breeding values for some of the boars. The accuracy is good e nough for all practical purposes and the implementation into selection deci sions.