Association between PrP genotypes and performance traits in an experimental Dutch Texel herd

The Dutch scrapie eradication programme for sheep is based on selection for the resistant ARR/ARR genotype of the ovine prion protein (PrP) gene. The aim of this study was to estimate the possible association of the PrP genotype and performance traits. The data included 963 genotyped females born between 1991 and 1998 in an experimental Texel flock, in which the Booroola gene was introgressed. The associations of the PrP gene were evaluated using a single trait animal model. The allele frequency from the herd mostly corresponds with genotyped rams in the Netherlands in the same period. The results indicate no significant associations with litter size, and only 3 of 112 estimated associations with weight, growth and body measurements were significant, with a low significance level. Therefore it can be concluded that selection for ARR/ARR rams in this experimental herd seem to have no effect on the performance traits due to association. The included data from this study is compared to data from other studies estimating associations between PrP genotype and performance traits. The comparison suggests of a possible small effect, which is only detectable in large datasets, which could be a result of linkage to the PrP genotype.