Rovere, Gabriel Alejandro;
Rovere, Gabriel Alejandro;
Publisher: GVO drukkers & vormgevers B.V.| Ponsen & Looijen, Ede, The Netherlands
The general goal of this thesis was to provide information useful for the breeding programme of the Royal Dutch Warmblood Studbook (KWPN) in relation with the ongoing specialisation of the population. Data provided by KWPN consisted of records from studbook-first inspection, competition performance on dressage and show-jumping, and pedigree information. Firstly, the effect of specialisation was studied on the connectedness between the subpopulations of dressage and show-jumping horses, using the pedigree information. Results indicated that relatedness between horses in the two subpopulations has been reduced to a low level, while relatedness within both subpopulations has been increasing consistently. A reduction in the number of influential ancestors in both subpopulations was observed. Secondly, it was analysed whether the specialisation for either dressage or show jumping has affected genetic parameters of traits recorded in the two subpopulations. Traits recorded at studbook-entry inspection were defined as a dressage trait or a show-jumping trait according to the type of horse that received the inspection. Bivariate analyses were performed to estimate the genetic correlation between the two traits. Results indicated that the specialisation process has resulted in a difference in mean trait values between dressage and show-jumping horses. However, differences in heritabilities for traits defined as dressage or show-jumping did not differ significantly, and the genetic correlations between them were not different from one considering their posterior standard deviation. Thirdly, the model to analyse performance in competition of dressage and show-jumping was studied. Results showed that performance in competition for dressage and show-jumping is a heritable trait (h2 ~ 0.11-0.13), and that it is important to account for the effect of rider in the genetic analysis. Fourthly, it was estimated the genetic correlation between the performance of horses in dressage and show-jumping competition, and the genetic correlations between traits measured early in life and performance in competition in each of the disciplines. Results showed that the genetic correlation between performance of horses in dressage and show-jumping was slightly unfavourable (-0.12). The genetic correlation between dressage and show-jumping tended to become more unfavourable over time, but this trend was not reflected in changes in the correlations between competition traits and traits recorded in the studbook-entry inspection. From this study it can be concluded that no extra benefit is to be expected from definition of a combined breeding goal. However, entirely separated breeding programmes for both disciplines are therefore not advisable. Constructing separate selection indexes would allow for optimal weighting of information sources such as studbook-entry inspection traits in accordance to the breeding goal of each sports discipline.