Genetic evaluation of Hanoverian warmblood horses for conformation traits considering the proportion of genes of foreign breeds

Abstract. Conformation data of in total 29 053 Hanoverian warmblood mares were used to determine whether genetic evaluation for conformation in the Hanoverian could benefit from the inclusion of the proportion of genes of foreign breeds in the model. For our analyses, we considered all Hanoverian mares born from 1992 to 2005 with available studbook inspection data. Genetic parameters were estimated univariately for eight routinely scored conformation traits (head, neck, saddle position, frontlegs, hindlegs, type, frame, and general impression and development), and height at withers from studbook inspections, in a linear animal model using Residual Maximum Likelihood (REML). Genetic evaluation was subsequently performed using Best Linear Unbiased Prediction. To investigate the effect of correcting for the proportion of genes of foreign breeds, two different models were used for the analyses. In Model 1, the fixed effect age at studbook inspection, and the random effect date-place interaction were considered. In Model 2, proportions of genes of Thoroughbred, Trakehner and Holsteiner were additionally included as fixed effects. Heritabilities of analyzed conformation traits and withers height ranged in both models between 0.10 and 0.57, with standard errors of ≤0.01. Pearson correlation coefficients determined between breeding values of corresponding traits using Model 1 and 2 were highly positive (>0.99), indicating little effect of the model on the results of genetic evaluation. According to the results using a model which includes the proportion of genes of Thoroughbred, Trakehner and Holsteiner as fixed effects will not relevantly improve genetic evaluation for conformation in the Hanoverian.