Genetic selection for dressage performance is a real option
Take Home Message: Breeding for improved dressage ability is feasible as the heritability is relatively high
Genetic selection for dressage performance is feasible in the UK sport horse population. The good news for breeders is that the heritability estimate in the population is relatively high compared to other international evaluations.
“In contrast to most international evaluations the UK data represents a wide variety of breeds,” said Isobel Stewart, who led a study to perform genetic evaluations of horses competing in dressage competitions in the UK.
“Breed may account for some genetic variance, producing an upwardly biased estimate of variation within a breed. Stallions are an elite selection of male horses, so better performance is predictable. This sex effect has been demonstrated in other populations,” she explained to delegates at the British Society of Animal Science’s annual conference.
Publication of estimated breeding values (EBVs) aids selection of animals for breeding to produce progeny with high performance ability. At least nine of the 10 top ranked horses in the 2008 Olympics individual grand prix freestyle dressage competition were from studbooks that perform genetic evaluations. “In the UK, however, little genetic evaluation of our sports horses has been performed, and EBVs are not currently predicted,” said Ms Stewart, revealing the rationale behind her Edinburgh-based team’s work.
It collated the results of national and international dressage competitions and pedigree data. Data were a selection of all records since 1994, where the horse had scored points for performance, a percentage scoring system was used, the horse had a UK passport, and it was registered to specific studbooks where pedigree data were available.
In the data analysed, 6,748 horses competed giving 148,997 competitive records. First generation pedigree data were available.
Analysis revealed that the heritability of percentage awarded was 0.18 and repeatability was 0.28. We also found that horse height, sex and age all had significant effects on performance,” said Ms Stewart.
“Stallions performed better than geldings and mares and performance improved with height from 1.47m, which coincides with the classification of a horse rather than pony.
“Performance improved from the youngest horses to a peak at age 10, and then declined slightly with increasing age,” she added.
To view proceedings of all summaries presented at the Annual Conference 2009 http://www.bsas.org.uk/Publications/Annual_Conference_Proceedings/ To view all Powerpoint presentations http://www.bsas.org.uk/Members_Area/ For further information contact: BSAS on 0131 445 4508 or bsas@sac.ac.uk
