Including fertility performance in the estimation of breeding values in pigs - 1st communication: Considering consecutive litters of a sow

This study explains the possible use of data from management programs for t he estimation of genetic parameters and breeding values with respect to fer tility. A usable modell and all the needed parameters are given for an esti mation of breeding values in the examined populations. The investigated data consists of 10475 records containing the consecutive litters of 2847 sows from 11 herds belonging to the "Hybridschweinezuchtver band Nord/Ost e.V." The involved populations are German Large White and cro ssbreds from German Large White boars with German Landrace sows. The two investigated models have been a pure repeatability model, consideri ng the consecutive litters of a sow as one trait and a modified model where the first litter and the following litters have been considered as separat e traits. The heritabilities of all traits are near 0.1. The genetic correlations bet ween the first and subsequent litters range from 0.74 to 0.96. Considering all litters as one trait is therefore possible. For the genetic evaluation in each of the populations we recommend a modifi ed repeatability model with the first litters considered as a separate trai t. This model allows a better inclusion of the different covariables (age a t first litter and farrowing interval) as well as a specific testing of the influence of the origin litter from the sow on their own first litter size .