Health status and conformation in young sport horses affect performance and longevity in competition

L. Jönsson^{1 *}, A. Näsholm¹, L., Roepstorff², A. Egenvall³, G. Dalin² and J. Philipsson¹

¹Department of Animal Breeding and Genetics, ²Department of Equine Sciences, ³Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden.

Few studies have evaluated the influence of variation in conformation and health in young sport horses, on present and future performance. The objective of this study was to estimate phenotypic and genetic associations between conformation and health status in young riding horses on one hand, and performance at the day of testing and in future competitions, including number of years in competition (NYC), on the other hand. Analyses included 8,238 horses examined for conformation, health and talents for jumping and dressage by independent examiners, during the Swedish Riding Horse Quality Test (RHQT) of 4-5-year-old horses, and lifetime competition results. Single trait linear models and multi-trait animal models were used, for phenotypic effects and genetic correlations, respectively. Results indicated both health status and conformation to have significant phenotypic and genetic effects on gaits and jumping performance scores at day of testing. Favourable genetic correlations between health status and performance reached 0.23 for jumping scores and 0.37 for gait scores. Genetic correlations with NYC were favourable, 0.25-0.31, for all health traits. Conformation also showed positive correlations with NYC ~0.2. Lifetime performance showed genetic correlations of 0.26-0.36 to health traits and of 0.28 for the most important conformation traits (head-neck-body). Horses of intermediate size, withers height 164-171 cm, were found to be most durable in competitions. Results suggest that selection for improved health status and conformation of the young horse will also improve desired performance traits and longevity of competition horses.