The value of using multilevel performances (from recreational to international) to the genetic evaluation for show jumping performance in Warmblood horses.

Abstract: Show jumping is a popular equestrian sport that requires a unique combination of jumping capacity and rideability. It has been shown that genetics play an important role in show jumping performance that has significant implications for horse breeding programmes. This gives an important opportunity for studbooks to breed horses with the potential to perform at the highest level in show jumping competitions. However, show jumping competitions are performed at various levels (from recreational to international level) but only national competition results are used by Warmblood studbooks in most genetic evaluations due to limited access to performances at international level. Moreover, the differences between levels have not been quantified which complicates a fair comparison of horses performing at different levels. Furthermore, it is questioned whether performance data at international level is of added value for predicting genetic merit for show jumping performance. Thus, the aims of this study were twofold. First, to estimate the variance components for show jumping performance at various levels in Belgian Warmblood horses. Second, to investigate the possible effect of the inclusion of show jumping performances at international level on the genetic evaluation for show jumping performance in Belgian Warmblood horses. This research analysed 1 967 358 show jumping competition records, and 118 175 pedigree records were used in genetic analyses to estimate heritabilities and genetic correlations between show jumping performance at different levels in Belgian Warmblood horses. Genetic analyses were performed including recreational or national or international level, Belgian data (recreational and national), and data of all levels combined. Pedigree data were provided by the Belgian Warmblood horse and Zangersheide studbooks. Competition records were provided by three organisations: Landelijke Rijverenigingen (recreational level), the Royal Belgian Equestrian Federation (national level) and Hippomundo (international level). Our results indicate that show jumping performance is lowly heritable at all levels (0.09-0.19) and performances at different levels are highly genetically correlated (0.63-0.93). Our research also shows that focusing on performances at international level only might be biased and is less informative to breeders. More importantly, a genetic evaluation combining performances at all 3 levels (recreational, national, and international) resulted in more accurately estimated breeding values. In conclusion, the use of multilevel performances is advised for not only Belgian but all Warmblood studbooks to provide more helpful information for breeders.