Use of individual race results in the estimation of genetic parameters of trotting performance for Finnhorse and Standardbred trotters

The heritability and repeatability for trotting performance traits were est imated from individual race results. Data comprised of records from 1991 to 1995 for 4808 Finnhorses and from 1993 to 1995 for 5869 Standardbred trott ers. The statistical model included the additive genetic effect of an anima l and two permanent environmental effects, and the fixed effects of sex, ag e, starting method*starting lane combination, driver and race. The first pe rmanent environmental effect described repeatability over a horse's career while the second one characterized repeatability within a racing year. Vari ance components for three trotting performance traits were estimated by the animal model and the method of restricted maximum likelihood (REML). Herit ability and repeatability estimates were moderately high for time at finish (h(2) =0.23-0.28 and r=0.50-0.57), moderate for ranking within a race (h(2 ) =0.12 and r=0.25) and low for earnings (h(2)=0.05-0.09 and r=0.15-0.18). Time at finish seemed to be the most usable measure of trotting performance because of its wide information substance. However, time at finish does no t take into account records of disqualified horses or of those which did no t finish, but use of earnings, either from individual race results or prefe rably from annual records, is one possible way to consider records of such horses.