Elsevier

Livestock Science

Volume 118, Issues 1–2, October 2008, Pages 99-112
Livestock Science

Optimization of breeding schemes for sport horses

https://doi.org/10.1016/j.livsci.2008.01.005Get rights and content

Abstract

A selection scheme for jumping sport horses is modelled with four stages of selection for males and one stage for females. The selection objective included three traits: conformation and gaits (CG, weighted 20%), competition jumping (CJ, weighted 60%) and a third trait (TT, weighted 20%) such as sperm quality or orthopaedic status. The first selection stage is based on knowledge of the pedigree with the aim of selecting horses suitable for CG test (at 3 years old) and CJ test (at 5 years old). The second stage includes the horse's own performance with respect to CG and CJ with the aim of selecting horses suitable for the TT test. The third stage is the selection of a limited number of males who are allowed to reproduce. The fourth stage (at 12 years old) takes into account the results of the horse's progeny. Females are selected in one step, whatever the number of performances measured at 5 years old. The annual genetic response was 9.4% genetic standard deviation of the objective, 2.6% for CG, 9.0% for CJ and 1.5% for TT. Results showed that selection by progeny testing did not contribute much to genetic response (12% of progeny issued from proven sires), the female pathway represented 26% of genetic response, TT was difficult to improve when the genetic correlation was unfavourable (− 0.6% genetic standard deviation for − 0.20 genetic correlation), and should consequently be directed towards the use of molecular markers. When compared with a selection scheme involving a station test, genetic response was the same if the breeding values used for selection before entering the station test took into account the results of the relatives for CJ and CG. This revealed the importance of an extensive performance test (like for competition performance) when designing breeding schemes for sport horses.

Introduction

Interest in horse sports and in horse breeding is on the increase. A relatively recent paper (Koenen et al., 2004) focused on breeding goals for sport horses, and this was followed by a review of the testing procedures used in different breeding schemes (Thorén Hellsten et al., 2006). Such breeding schemes share the same objectives but the procedure varies in different European countries. In France, for the last 20 years, selection has mainly focused on jumping horses, and is based on success in competition tests (Dubois and Ricard, 2007). The current objective of French breeders is to produce international jumping horses with increasing attention paid to functional traits such as conformation, gaits, riding temperament, locomotion problems and reproductive ability including aptitude for artificial insemination in males. New proposals have been made for the improvement of existing breeding schemes such as in-station selection tests for stallions. In some European countries, stallions are selected in special test stations after the measurement of performance (Bruns and Schade, 1998, Huizinga, 1990). These test stations enable the comparison of different stallions in the same environment but only a small number of candidates can be tested due to the cost of such structures. In Sweden special performance tests are used for the selection of stallions, with a week-long test that is repeated after an interval of 6-months, however, the Swedish test does not take place in a testing station. It shares the same characteristics with respect to genetic improvement, i.e. better heritability, but is limited to a small number of stallions (Gerber Olsson et al., 2000). The relevance of such breeding schemes has already been discussed in their own context: Ström and Philipsson (1978), Huizinga (1990), Philipsson et al. (1990), Koerhuis and van der Werf (1994), Bruns and Schade (1998), Gerber Olsson et al. (2000), Olsson (2006), Thorén Hellsten et al. (2006).

This study had three main objectives: 1. to model the standard breeding scheme currently used in France with new traits added to the breeding objectives, 2. to measure its characteristics and its efficiency, and 3. to compare it to an in-station test scheme.

Section snippets

Selection objective

The selection objective was a linear function of three traits. Competition jumping (CJ) was the main objective. The main secondary trait was conformation and gaits (CG). Other traits could be temperament, sperm quality or orthopaedic diseases. These traits are difficult and expensive to measure and require specific tests for temperament, sperm analysis for sperm quality, and X-Rays for developmental and orthopaedic diseases. We added a third trait (TT) to the selection objective, which could be

Genetic trend

The annual genetic trend of the standard breeding scheme was + 9.4% standard deviation units for the selection objective. Table 1 summarizes the genetic trends of the different breeding schemes. For CG, the genetic trend was + 2.6% standard deviation units, for CJ, the genetic trend was + 9.0% standard deviation units, and for TT, the genetic trend was + 1.5% standard deviation units. The male pathway contributed 74.2% of genetic progress.

Active stallions and broodmares

The replacement of the population required 333 active

Discussion

The limited sensitivity of the results to the parameters used in the model imply that our model results for the standard breeding scheme are sufficiently stable to make strategic decisions in breeding plans for jumping horses. Our main results were: 1. very atypical selection on progeny, 2. marked heterogeneity of selection among birth cohorts, 3. the need for an extensive field test or competition test whatever the breeding scheme of stallions (with or without an in-station test), 4. the

Conclusion

Four points are important in breeding schemes for sport horses. The first is that a progeny test is not essential (12% of progeny are issued from proven sires), except for rapid culling of stallions before their natural death (after 7 years of use). The second point is that selection of females should be taken into account as it can contribute 1/4 of genetic response. The third point is that extensive performance testing for competition jumping is necessary whatever the selection scheme for

References (26)

  • HugasonK. et al.

    Efficiency of three-stage selection of stallions

    J. Anim. Breed. Genet.

    (1987)
  • Huizinga, H.A., 1990. Genetic studies on performance of dutch warmblood riding horse. Doctoral thesis. Wageningen. The...
  • Jaitner, J., Reinhardt, F., 2006....
  • Cited by (0)

    View full text