762. Effects of Selection on Breed Composition of the Spanish Sport Horse Population

The Spanish Sport Horse (CDE) is a recently developed composite breed selected mainly for show jumping performance since 2002, when the CDE studbook was officially founded. The main aim of this study was to highlight the effects of selection on this breed, regarding the breeds composition, and its repercussion in the breeding program. The CDE pedigree, with 47,884 animals (21,163 registered as CDE), was used for the analyses, including 10 breed groups corresponding to the major horse breeds present in the CDE Studbook. Two periods were considered to analyse the genetic contribution of founders for each breed group. Estimated breeding values (EBV) were available for show jumping discipline. Results showed that Other Horse Breeds group had the highest genetic contribution to CDE, followed by the Spanish Purebred. A small genetic progress was observed, as founders from most breeds showed lower EBVs than their descendants. This indicates that the genetic selection made has been effective, even though the management was not perfect.