Genetic variation in competition traits at different ages and time periods and correlations with traits at field tests of 4-year-old Swedish Warmblood horses

Abstract

For many years, the breeding value estimation for Swedish riding horses has been based on results from Riding Horse Quality Tests (RHQTs) of 4-year-olds only. Traits tested are conformation, gaits and jumping ability. An integrated index including competition results is under development to both get as reliable proofs as possible and increases the credibility of the indexes among breeders, trainers and riders. The objectives of this study were to investigate the suitability of competition data for use in genetic evaluations of horses and to examine how well young horse performance agrees with performance later in life. Competition results in dressage and show jumping for almost 40 000 horses from the beginning of the 1960s until 2006 were available. For RHQT data of 14 000 horses judged between 1988 and 2007 were used. Genetic parameters were estimated for accumulated competition results defined for different age groups (4 to 6 years of age, 4 to 9 years of age and lifetime), and for different birth year groups. Genetic correlations were estimated between results at RHQT and competitions with a multi-trait animal model. Heritabilities were higher for show jumping than dressage and increased with increasing age of the horse and amount of information. For dressage, heritabilities increased from 0.11 for the youngest group to 0.16 for lifetime results. For show jumping corresponding values increased from 0.24 to 0.28. Genetic correlations between competition results for the different age groups were highly positive (0.84 to 1.00), as were those between jumping traits at RHQT and competition results in show jumping (0.87 to 0.89). For dressage-related traits as 4-year-old and dressage competition results the estimated genetic correlations were between 0.47 and 0.77. We suggest that lifetime results from competitions should be integrated into the genetic evaluation system. However, genetic parameters showed that traits had changed during the over 35-year period covered due to the development of the sport, which needs to be considered in future genetic evaluations.Keywords: riding horses, dressage, show jumping, performance test, genetic parameters ImplicationsTo estimate reliable breeding values of Swedish Warmblood horses and to reduce bias due to pre-selection of horses for competition, it is important to integrate all available information from both young horse tests and competitions. Lifetime competition results are recommended and high genetic correlations were estimated between results in competition and results from tests of 4-year-old. The equestrian sport has changed during the 20th century, and this study shows that competition results do not mean the same throughout the 35-year long period of recording. Future studies will investigate how to handle competition data from different time periods in genetic evaluations.

Estimation of genetic parameters for morphological and functional traits in a Menorca horse population

“…For the performance traits analyzed here, the heritabilities were in agreement with other authors (Ricard et al, 2000;Viklund et al, 2010), even though all the comparisons were made with caution because of the small amount of data. Fitting rider effect in the models has been often controversial when analyzing sport performance in horses (Kearsley et al, 2008;Bartolomé et al, 2013).…”

The use of novel phenotyping methods for validation of equine conformation scoring results

“…As conformation scoring procedures and the underlying classification protocols are objects of an intensively led discussion since the 1970s (Grundler and Pirchner, 1991;Molina et al, 1999;Viklund et al, 2010;Sanchez et al, 2013;Duensing et al, 2014), we aimed to test the major statements frequently reported within this issue. One central requirement within classifications of conformation is the reliability of ratings.…”

“…Due to this situation, typical for horse breeding programs, several studies analyzed the relationship of indicator traits derived from linear type trait scoring procedures with performance data collected in the field or at standardized test situations (Koenen et al, 1995;Molina et al, 1999;Cervantes et al, 2009;Viklund et al, 2010;Sanchez et al, 2013). The derived correlation structures are still strong strategic and economic arguments for breeding organizations to focus on conformational evaluations of type, leg and gait traits.…”

Effects of long-time series of data on genetic evaluations for performance of Swedish Warmblood riding horses

“…Data go back to the beginning of the 1970s. Earlier studies (Viklund et al, 2008 and2010) have shown that some of the recorded traits have not stayed the same throughout the years. The heritabilities and variances changed over time, and the genetic correlations between traits recorded at different time periods were sometimes considerably less than unity.…”

“…Genetic correlations between traits in the different judging periods ranged between 0.48 (correctness of legs) and 0.97 (walk under rider). For dressage competition traits, heritabilities decreased slightly between birth year groups 1953 to 1983 and 1992 to 2002 (from 0.18 to 0.14), whereas they increased slightly for show jumping (from 0.31 to 0.34; Viklund et al, 2010). For both disciplines, the phenotypic variances decreased between traits recorded in the early period and late period (0.61 to 0.50 for dressage and 0.61 to 0.47 for show jumping).…”