Prediction of Adult Conformation Traits from Shape Characteristics of Pura Raza Español Foals

Horse conformation has been proposed as an indirect indicator of performance, since their genetic correlations are often positive and high. In Pura Raza Español (PRE) horses, the selection of conformation traits more related to functionality and performance allows a pre-selection of animals and contributes towards saving costs and increasing the genetic progress. The aim of this paper is to evaluate the predictability of 16 conformation traits (14 body measurements and 2 linear conformation traits) in adult PRE horses, focusing on the conformation traits of foals. The dataset included 155,716 records (82,408 young and 73,308 adult horses) with conformation traits from 142,244 different horses, aged between 1-36 years old. Animals between 1-3 years old were included in the ‘young’ group and older animals in the ‘adult’ group. A univariate General Linear Model procedure followed by a Tukey-post-hoc test were used to assess the statistical significance of non-genetic effects. Heritability values were estimated univariately. The fitted models included breeder, age and inbreeding (F) as covariates, and sex and coat colour as fixed effects. Coat colour and F were significant for 75% and 87.5% of the traits analysed, respectively; and the other effects analysed were significant for all the conformation traits. Heritability values ranged between 0.178±0.0063 and 0.795±0.0098 in young horses, and between 0.273±0.0038 and 0.894±0.0007 in adult horses. The genetic correlations of the conformation traits between young and adult horses were above 0.75 for 93.75% of the conformation traits analysed, which confirms the efficiency of pre-selection in young horses based on conformation features to predict their adult performance.