Livestock Production Science 65 2000 81–89 www.elsevier.com locate livprodsci
Genetic parameters for traits at performance test of stallions and correlations with traits at progeny tests in Swedish
warmblood horses
a , b
a a
´ ¨
Elisabeth Gerber Olsson , Thorvaldur Arnason , Anna Nasholm , Jan Philipsson
a
Department of Animal Breeding and Genetics , Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden
b
˚ IHBC AB
, Knubbo, S-744 94 Morgongava, Sweden Received 12 July 1999; received in revised form 12 November 1999; accepted 12 November 1999
Abstract
Genetic parameters for traits evaluated in the Swedish stallion performance test SPT and correlations between stallion performance test traits and 4-year-old offspring results from field tests were estimated. Heritability coefficients were on
average 0.40 for individual gaits under rider and 0.23–0.47 for jumping traits at SPTs. Repeatabilities between tests at 6-month intervals were 0.75–0.77 for gaits and 0.38–0.58 for jumping traits. The genetic correlation between the gaits
ranged from 0.30 to 0.71. Positive genetic correlations were found between gaits under rider and jumping traits 0.14–0.54, thus breeding for both characteristics is facilitated. Free jumping results were highly correlated 0.93 to results in jumping
under rider, and because of their higher heritability the former are very suitable for selection purposes. Genetic correlation estimates between a trait in SPT and the same trait at 4-year-old offspring field test were unity for gaits under rider and
jumping. The genetic correlations between gaits and jumping at the two different tests were 0.26–0.35. It was concluded that the field tests are well suited for early progeny testing of the stallions, and will improve the accuracy in selection of stallions
for performance traits.
2000 Elsevier Science B.V. All rights reserved.
Keywords : Riding horses; Performance; Animal model; Heritabilities; Correlations
1. Introduction based on experiences and results of European 100-
day tests Bade, 1974; Bruns et al., 1985; Huizinga The Swedish system for performance testing of
et al., 1991b and genetic analyses of Swedish field warmblood stallions SPT was developed in the late
tests of 4-year-old riding horses Thafvelin et al., 1970s and the early 1980s. The design and gradual
1980; Darenius et al., 1982. The evaluations at the development of the Swedish performance tests were
SPT were done by experienced national and interna- tional judges and trainers. The stallions could partici-
pate in three tests, located at Flyinge in the southern
Corresponding author. Tel.: 146-18-672-789; fax: 146-18-
part of Sweden, with an interval of 6 months from
672-648.
3.5 to 5.5 years of age. The stallions were at each
E-mail address : elisabeth.olssonhgen.slu.se E. Gerber Ol-
sson
occasion tested during 4 days, comprising evaluation
0301-6226 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 3 0 1 - 6 2 2 6 9 9 0 0 1 7 6 - 1
82 E
. Gerber Olsson et al. Livestock Production Science 65 2000 81 –89
for soundness, conformation, gaits under rider, free genetic trend in the population based on BLUP-
jumping and jumping under rider. The stallions were Animal model evaluations is estimated with infor-
also scored for temperament and general appearance mation from the RHQT and the trend has been
´ in the tests for gaits under rider, free jumping and
increasing rapidly during the last 10 years Arnason jumping under rider. The stallions usually had to be
et al., 1997. When considering horses born from approved at two out of three tests to be licensed for
1988 to 1992, the annual genetic progress for gaits breeding. Annually about 200 stallions were pre-
and jumping, respectively, have been about 0.05 and inspected for conformation and soundness. About
0.03 genetic standard deviations per year. 40–60 were selected to take part in the stallion
The purpose of the SPT is to select sires of the performance tests and on average 8–12 of these
coming generation of successful sport horses. As stallions were finally approved for breeding.
Ohlsson and Philipsson 1992 have concluded, In 1997 some changes were introduced in the
performance at RHQT is highly correlated to later stallion performance test. The test is now done as a
competition performance, it is of great interest to 9-day-long station test at 4 years of age at Flyinge.
find out to what extent the SPT and RHQT results The stallions are preselected in the autumn at 3.5
are genetically related. years of age, for conformation, soundness and free
The objectives of this study were to estimate jumping. The latter trait is therefore excluded from
heritabilities, genetic and phenotypic correlations and the regular stallion performance test. The stallions
repeatabilities for traits scored in the stallion per- are also judged by foreign test riders in the new test.
formance tests as well as correlations between The SPT is used for phenotypic selection among
stallion performance test results and 4-year-old field prospective breeding stallions, but until now it has
performance records of their offspring. These param- not been investigated if heritabilities and variances
eters are necessary for construction of integrated for the traits tested are high enough for an efficient
indexes to be used for performance evaluations and selection. Because the SPT was done as repeated
continued evaluations of stallions based on early tests
it was
important to
investigate the
re- progeny results. The parameters are also useful for
peatabilities of the results, and thereby determine the determining the opportunities of improving or sim-
effects of reducing the number of tests. The correla- plifying the stallion performance tests.
tions between traits in the Swedish stallion per- formance test have not been estimated before and it
would be interesting to know their interrelationships
2. Materials
