Multi-trait evaluation of Swedish warmblood stallions at station performance tests including field and competition records

摘要

The aim of this thesis was to estimate genetic parameters for stallion performance test (SPT) results and their correlations with riding horse quality tests (RHQTs) as well as competition results in show jumping and dressage. The thesis also investigates the possibility of increasing the accuracy in selection of Swedish Warmblood stallions by combining their performance results with information about performance of related horses RHQTs and competitions in show jumping and dressage. Data were collected from records covering the 801 stallions used in the analyses. Data on approximately 14 900 horses with RHQT results, 26 800 horses with results in show jumping and 14 200 horses with results in dressage competitions were also analysed. Mixed model analyses using Restricted Maximum Likelihood were applied for estimation of genetic parameters. Estimated heritabilities were 0.38–0.42 for individual gaits under rider and 0.23–0.65 for jumping traits in SPT. Heritabilities for competition traits were 0.17 for dressage and 0.27 for show jumping. The heritabilities for traits recorded in the RHQT varied between 0.19 and 0.36. Genetic correlations between all jumping traits assessed at the SPT were very high and positive, varying between 0.87 and unity. Jumping-related traits judged in the SPT have positive and high genetic correlations with show jumping results in competitions (0.78–0.96). Gaits judged in the SPT and results in dressage competitions had somewhat lower genetic correlations (0.44–0.77). The genetic correlation between conformation and results in dressage competitions was 0.22. Genetic correlations between jumping recorded in the SPT and jumping recorded in the RHQT were 0.72–1.00, whereas gait correlations were 0.90–1.00. Overall, the results suggest that the traits measured in the SPT are reliable indicators of competition performance. The accuracy of the SPT rises considerably when if information on performance of relatives in competitions in show jumping and dressage, and in the RHQT are used simultaneously. For the breeding goal trait ‘show jumping’ the mean accuracy rose from 0.60 to 0.68 for stallions born in Sweden, an increase of 13%. For stallions born outside Sweden, the corresponding figure was 5%. With the goal trait 'dressage' information from the RHQT and competition results in dressage improved the accuracy from 0.41 to 0.55 for stallions born in Sweden, an increase with 39%. For imported stallions the improvement was 11%. Thus, it is important to consider pedigree information in genetic evaluations of stallions in performance tests.