Repeatability of kinematics traits of free jumping in Brazilian sport horses

• This study estimated repeatability of kinematics traits jumping horses at three ages.
• Repeatability values were lower at first and higher at the last evaluation.
• The highest repeatability values were obtained for the horse-conformation traits.
• Kinematics traits of free jumping had moderate to high repeatability estimate values.

This study was carried out to estimate the repeatability of kinematics traits associated to the performance of free jumping young horses at three different ages. Free jumpings from 108 young horses were evaluated, resulting in a total of 1067 jumpings. All the animals were assessed at three age classes, at 22–25; 29–32 and 36–39 months of age, with five free jumping at each age classes over 0.60 m, 0.80 m and 1.05 m high a vertical fence, respectively. Eighteen horse׳s anatomical points were highlighted by reflective markers. Jumpings were recorded by a 100-Hz camera and analyzed by the Simi Reality Motion Systems® software. The repeatability ranged from 0.18 to 0.89 at the three age classes. The lowest repeatability value was obtained for the radial-metacarpal angle at 22–25 months of age, as well as, the highest repeatability value was obtained for the coxofemoral angle at 36–39 months of age. In general, the repeatability values were lower at the first age class, with younger animals and the obstacle was lower, and higher repeatability values at the last evaluation, with higher fence and older horses had already twice performed the experimental protocol. The highest repeatability values were obtained for the horse-conformation traits measured at the trunk. Scapulohumeral angle, coxofemoral angle, neck angle and landing distance required fewer jumpings for young horses׳s jumping ability, where other traits, such as last stride length prior to jumping, forelimbs heights at jumping and radial-metacarpal angle, required additional measurements.