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Doctoral thesis, 2010

Genetic evaluation of Swedish warmblood horses

Viklund, Åsa

Abstract

The main breeding objective for the Swedish Warmblood horse (SWB) is to produce competitive horses for show jumping or dressage. The aim of this thesis was to provide information to improve the breeding programme for SWB by investigating the usefulness of different sources of data for genetic evaluation and by studying the realised selection practices and genetic trends of the SWB population. Data from three information sources were used in the analyses: competitions (in show jumping and dressage), young-horse test for 3-year-olds (YHT) and riding horse quality test (RHQT) for 4-year-old horses. At YHT and RHQT the horses are subjectively scored for conformation, gaits and jumping ability. The moderate to high heritabilities and high genetic correlations between different traits showed that all three information sources could be integrated in the genetic evaluation with a multi-trait BLUP animal model. The main objective is to breed horses that can achieve good lifetime competition results, and results from YHT and RHQT provide early information of the horses. Multiple information sources allow many horses to be tested, leading to accurate breeding values (EBVs) and opportunities for high selection intensity. Competition and RHQT data go back to the early 1970’s and the traits have changed over time due to development of the sport, change in the population and breeding objective, and change in judging at RHQT. The analyses showed that all data can be used in the genetic evaluation to estimate reliable and unbiased EBVs. The genetic progress in both dressage and show jumping increased considerably in the mid 1980’s due to stronger selection of stallions at the improved stallion performance test in the late 1970’s, importation of superior stallions, introduction of young-horse testing at RHQT, and the beginning of predicting EBVs based on RHQT data with a BLUP animal model in 1986. The genetic trend of broodmares followed the same trend as non-selected horses, and the achieved genetic progress was primarily a result of stallion selection. In the future, emphasis should be put on more effective use of EBVs for selection of stallions and mares, both at young age and when progenies of stallions have been tested.

Keywords

horses; animal breeding; breeding value; animal performance; heritability; genetic correlation; trends

Published in

Acta Universitatis Agriculturae Sueciae
2010, number: 2010:48
ISBN: 978-91-576-7461-6
Publisher: Dept. of Animal Breeding and Genetics, Swedish University of Agricultural Sciences