Relationship between morphology and performance: Signature of mass-selection in Pura Raza Español horse

• PRE conformation has evolved over time, remaining constant sexual dimorphism.
• PRE selected for dressage have their own conformation.
• It is feasible a genetic selection of the PRE dressage morphological traits.

Horse conformation is considered an indicator of performance, which plays an important role in breeding decisions. Apart from conformation, Pura Raza Española horse (PRE) breeding goal is to improve its functionality, and they are being selected by some studs over the last decades as a dressage sport horse. This process may be accompanied by a mass selection which has probably caused morphological changes in recent decades. This paper has three main aims: To evaluate the development of body conformation in PRE over the last three generation intervals (GI), to evaluate the current morphological differences of PRE selected for dressage competitions by specialized stud farms with others with the others and to estimate the genetic parameters in order to show the response to individual mass selection. A maximum of 26 morphological measurements (MM) from 52,681 PRE collected between 1980 and 2013 were split into three groups of 11 years (GI). The GLM showed that gender and GI were significant factors in all the MM analyzed in the last 30 years. In the current PRE population, gender and belonging to a stud attached to the official dressage improvement program were significant factors for 17 and 16 MM respectively. The heritabilities ranged from 0.31 (angle of shoulder) to 0.80 (height at withers). There 57.5% of the genetic correlations were higher than 0.50. The predicted breeding values were different for dressage and non-dressage subpopulations.