Genetic parameters of biokinematic variables at walk in the Spanish Purebred (Andalusian) horse using experimental treadmill records

The breeding scheme of Spanish Purebred (SPB) horses includes the selection of dressage performance as a main objective. Specific characteristics of the gaits are required for dressage aptitude and some could be selected for genetically. The gait of 130 SPB horses was recorded on a treadmill at walk (1.7 m/s). Nineteen biokinematic variables were analysed, 18 were directly measured from the video sequences and 1 estimated from the measurements. The data were used to estimate genetic parameters of gaits (heritability and genetic correlations). The aim was to select the biokinematic variables to include in the breeding scheme of this breed, based on their genetic parameters and their relation with dressage performance.The resulting heritabilities were medium-high (51.1% with heritability higher than 0.5). This implies a high response for selection which allows an indirect early selection for dressage performance. The genetic correlations are abundant and range between 0.28 and 0.99, which allows a reduction in the number of selected variables.Based on our results, a selection scheme should include: stride duration and length; fore and hindlimb duration and length; hindlimb maximum height of hoof; maximal retraction–protraction range of forelimb; hindlimb stance phase duration and fore and hindlimb swing phase duration.