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Research article2007Peer reviewed

Genetic analysis of competition data on Icelandic horses

Albertsdottir E, Eriksson S, Nasholm A, Strandberg E, Arnason T


In a study of the possibility of using competition data in the genetic evaluation of Icelandic horses, data from competitions held in Iceland between 1999 and 2004 and in Sweden between 1998 and 2004 were analyzed to estimate the genetic parameters of competition performance traits. The data-sets from both countries included 18 982 records of 3790 horses in 379 different events. Two types of competition were included: sport competitions and gaeoinga competitions performed on oval tracks and on a straight track. Each type of competition involves several disciplines in which the horses are ridden in the various gaits. The traits analyzed were two different measures of four-gait, five-gait and tolt, and one pace trait. In both the four-gait and five-gait tests the gaits walk, trot, tolt and gallop are exhibited. In the five-gait test, pace is also exhibited. The traits tolt and pace are performances of these single gaits. Highly correlated and similar traits were combined, and three new traits relating to tolt, four-gait and five-gait were formed. No large differences in means or standard deviations of traits were found between countries. All traits were approximately normally distributed. Genetic parameters were estimated using linear animal models including the fixed effects of sex, age and event for all traits, and the level of discipline was included for some traits. Random permanent environmental effects were also included. Estimated heritabilities were moderate to high, ranging from 0.18 to 0.21 for sport-competition traits, from 0.33 to 0.35 for gaeoinga-competition traits and from 0.19 to 0.22 for combined traits. Estimated genetic correlations between different sport-competition traits varied from 0.63 to 0.96, and between the two gaeoinga-competition traits it was estimated at 0.43. Genetic correlations between sport- and gaeoinga-competition traits ranged from -0.42 to 1.00. It was concluded that competition traits are suitable to include in genetic evaluations. (c) 2006 Elsevier B.V. All rights reserved

Published in

Livestock Science
2007, Volume: 110, number: 3, pages: 242-250