Genetic parameters for linear type and gaits traits in the belgian warmblood horse

Linear scoring is one possibility to assess the conformation and gaits of the horse. In 2003, a linear scoring system was introduced for the Belgian Warmblood Horse (BWP). Since then, 987 mares aged of 3 or 4 years have been scored on a scale between -20 and 20. The aim of this study was to estimate genetic parameters for the height at withers and linear traits (17 type, 10 limbs and 6 gait traits). A multi-trait animal model including fixed effects for jury, age and location (date x place of appraisal) has been implemented. Genetic parameters for the 34 traits were computed applying a canonical transformation and an EM-REML algorithm with an additional deceleration step (MTC program). Heritabilities of the 33 linear traits were in the range of 0.16 and 0.55 and heritability of the height at withers was 0.37. Genetic correlations ranged from -0.60 to 0.98 with 75 correlations higher than |0.5|. The highest positive correlations were within traits of walk and traits of trot. The volume and the substance of legs were the most negatively correlated. The results show that the linear scoring system can capture genetic variation and could be used for breeding value estimation.