Untersuchungen zur Fruchtbarkeit bayerischer Besamungseber der Rasse Pietrain auf der Basis von Ferkelerzeugerdaten

The objective of the paper was the estimation of variance components for the paternal impact on litter size in commercial weaner producer herds in pigs. A total of 37 855 litters from 472 herds with a high proportion (72 %) of artificial insemination (AI) were selected from all available records. All litters were single crosses between Pietrain AI-boars and Landrace sows. Two different statistical models were used in the variance component estimation. Within each model, the herd-year effect was considered as a fixed and random effect, respectively. For most of the analyzed models, the sire-effect turned out to be about 0.6 % of the total phenotypic variance. The repeatability of the number of piglets born alive (LBP) was estimated between 14 and 15 % of the phenotypic variance. The application of the estimated parameters in a genetic evaluation of the AI-boars resulted in a difference of 0.92 LBP between the two extreme boars. The average accuracy of the estimated breeding values was 37.5 %. A genetic evaluation of AI-boars for male fertility seems to be feasible, since the additional cost is small. However, further studies to include other traits, especially the non-return rate, in a reproductive index are needed.