Beatrice Ray from United States of America finished her EMABG thesis in summer 2011 at the University of Agriculture Sciences (SLU) in Uppsala, Sweden.
Genetic analysis of eventing data in the Swedish Warmblood population
Within Sweden the genetic evaluation of eventing has never been done. With the evaluation of eventing for the Swedish Warmblood (SWB) population a more conclusive summation can be developed for individual horses since many compete within more than one discipline. In this study the English equestrian discipline eventing was genetically analyzed in the SWB. Descriptive statistics on the population was also analyzed. This was completed by using competition results from 1961 to 2009 and results from Riding Horse Quality Test (RHQT) for 4-year-old horses from 1973 to 2010. Eventing has a small number of competing horses when compared to show jumping and dressage. It was found that an eventing horse competes on average 2.1 years in eventing competitions. The horses seem to start at a later age since the mean age of 8.5, during competition, was found. Then 85% of horses that competed in eventing also competed in other disciplines. Eventing and show jumping was the highest combination of disciplines. There were also more male horses than mares that competed in eventing which corresponded to other studies.
An animal model was used to analyze different traits reflecting eventing performance, and at different ages and to investigate correlations to show jumping and dressage and traits judged at RHQT. The eventing traits points, placing, and points per placing were all found to be heritable (0.06-0.17). There were high genetic correlations between three specific age groups (4 to 6 years of age, 4 to 9 years of age and lifetime) ranging from 0.76 to 0.99. The trait accumulated lifetime eventing points was suggested to use in genetic evaluation due to higher genetic variance and to include as much information as possible. Lifetime accumulated points were also used for show jumping and dressage. Show jumping was found to be moderately correlated to eventing with a genetic correlation of 0.44 whereas dressage was not found to be correlated to eventing. For RHQT traits associated with jumping (jumping technique and temperament for jumping) and canter the correlations to eventing were moderately correlated (0.31-0.41) and the rideability was found to have a correlation of 0.14 to eventing.
From the high correlations between the three specific age groups in eventing it was concluded that using the information of points earned in eventing competitions by younger horses could predict the performance outcome at an older age. The genetic trend for the estimated breeding values was found to be increasing even though there is no selection for eventing horses in Sweden at this time. Due to the moderate correlation between eventing and show jumping, and between eventing and jumping traits in RHQT, selection for better show jumping SWBs would also have a positive effect on the eventing SWBs. Overall, the eventing horses within the SWBs are slowly becoming better without direct selection but if selection was desired the performance of younger eventing horses could be used to predict competition performance later in life.