J. Sebelikova et al., Analysis of factors influencing the performance of English Thoroughbred horses in the Czech Republic, CZEC J ANIM, 45(5), 2000, pp. 209-215
Significance of important factors influencing one of the main parameters of
performance in the English Thoroughbred, i.e. general handicap (GH), was d
etermined. GH data from flat races of Thoroughbred horses in the Czechoslov
ak Republic in 1968-1993 and in the Czech Republic in 1994-1996 were used f
or analyses. Evaluations were carried out separately for each age category:
GHs of two-year, three-year and four-year horses. Two linear models with m
ixed effects were used. Model 1 comprised these factors: year of birth (rac
ing season), sex, father, mother's GH and mother's age. All factors were fi
xed except the factor father, it was considered as random. The factor fathe
r was omitted from model 2, the other effects were the same as in model 1.
An analysis to determine the significance of differences between effects wi
thin factors was made by help of model 1. The factors father and mother's G
H were significant in all age categories, the factor mother's age was insig
nificant in all categories, and the factors year of birth and sex were sign
ificant in two age categories every time. A variation-covariance analysis w
as made by means of model 2 when means were estimated by the least-squares
method (LSM) for the year of birth, sex, mother's GH and mother's age. GH v
alues ranged from 55 to 64 kg in all three age categories between 1976 and
1988, but there was a steep fall of GH values beginning in 1989 and 1990 an
d lasting to the end of observations in 1993; it was likely to be caused by
a different handicapper. It was confirmed by the highly significant factor
mother's GH that this information should be taken into account to estimate
breeding value. Mother's age was insignificant in all age categories in mo
del 1 while in model 2 it was significant in two-year horses only. A conclu
sion can be drawn on the basis of model 1 with higher informative capacity
that no adjustment to the factor mother's age is necessary, that means it n
eed not be applied to estimate and/or predict breeding value.