The genetic relationships between conformation assessment of gilts and sow production and longevity

Abstract

The longevity of sows is important for both the production economy and animal welfare. This study suggests that a selection for several conformation traits scored on gilts by utilizing phenotypic records from nucleus herds can contribute to a better longevity in sows. The aim of our study was to investigate the heritabilities and genetic correlations between conformation traits measured on unselected gilts, piglet production and longevity of the sows in the Norwegian Landrace population in order to contribute new knowledge on the relationship between conformation and longevity traits. For this study, eight phenotypes from a total of 78,000 gilts and sows were utilized; the traits were hind and front leg quality, motorics, hind leg standing under, the sum of the individual piglet weighed at 21 days in the first two litters (LWT), the total number of piglets born in the first two litters, the ability to stay in production for two parities (STAY) and the maximum parity number before culling (MAXL). The data for STAY and MAXL was analysed with two different models, both with and without correcting for breeding value (EBV) at culling. The latter is correcting for the fact that in nucleus herds sows are culled due to low EBVs. Our study found low to moderate heritabilities (0.05≤h2≤0.24) for all traits and substantial genetic correlations between most of the conformation traits (0.28≤r2≤0.66). The heritability of STAY and MAXL became significantly greater when including a correction for EBV at culling, and the genetic correlation between STAY and front leg quality became significant (rg=−0.12). This indicates that if the data from nucleus herds are used, a correction for EBV will improve the estimates. The results from our study show that there is not a strong genetic relationship between the conformation traits of the gilts and longevity. The inclusion of front and hind leg quality as traits in the breeding goal can contribute to increased longevity, although the results of such an indirect selection to longevity would be slow. Selection for improved conformation can counteract an undesired development in longevity.