Genetic analysis of lifetime performance and fertility traits in the pig breeds Large White, German Landrace and Pietrain

In this study heritabilities and additive genetic correlations for the traits length of productive life, number of piglets born alive in total lifetime of the sow, number of piglets born alive in the first litter and in litters 2 to 10 were estimated using multivariate animal models for the pig breeds Large White (DE), German Landrace (DL) and Pietrain (PI). The data set analyzed included 654 DE sows, 12.873 DL sows and 6.472 PI sows. The fixed effects in the model used were the age of first farrowing, the mean number of days between consecutive farrowings and the litter number of the 2nd to 10th litter. The additive genetic effect of the sow and the effects of herd-year-season-classes and of the permanent environment of the sow during the 2nd to 10th litter were included as random effects. Heritabilities of the length of productive life estimated in trivariate and bivariate animal models, respectively, were h(2)=0.19 and 0.17 in DE sows, 0.16 and 0.10 in DL sows and 0.22 and 0.20 in PI sows, respectively. The corresponding values for the trait number of piglets born alive in total lifetime of the sow were h(2)=0.37 and 0.18 (DE), h(2)=0.39 and 0.12 (DL) and h(2)=0.32 and 0.18 (PI), respectively. The estimates of the number of piglets born alive in the first litter were h(2)=0.19 (DE), 0.14 (DL) and 0.11 (PI), while the estimates for the number of piglets born alive in the litters 2 to 10 reached h(2)=0.18 (DE) and 0.16 (DL and PI). The additive genetic correlations between the different traits of lifetime performance and of fertility were favourable in all breeds. This leads to the conclusion that selection for fertility causes increasing length of productive life and higher lifetime performance at the same time. The additive genetic correlations between the length of productive life and number of piglets born alive in the first litter and the 2nd to 10th litter, respectively, amounted to r(g)=0.57 and 0.77 in DE sows, r(g)=0.40 and 0.67 in DL sows and r(g)=0.15 and 0.55 in PI sows, respectively. The trivariate estimates for the additive genetic correlations between the two different traits of fertility were r(g)=0.87 (DE), r(g)=0.80 (DL) and r(g)=0.68 (PI). The additive genetic correlations between the traits of lifetime performance were r(g)=1.00 in DE sows, 0.95 in DL and 0.96 in PI sows.