Íslenskar landbúnaðarrannsóknir - 01.03.1979, Blaðsíða 97

ÍSL. LANDBÚN.
j. agr. res. icel. 1979 11, 1-2: 95-102
Studies on traits in
the Icelandic toelter horses
II. Selection index.
PORVALDUR ÁRNASON
ABSTRACT
The basic theory of selection indices was briefly reviewed. A selection index for individual selection was
constructed, including ten traits of Icelandic toelter horses. The relative economic values ofeach trait were
taken from a scoring index used on the Icelandic horse-shows. The estimated genotypic variance/covarian-
ce matrix was however not positive definite. An example oferroneus „solutions" ofindex values for progeny
tests were given.
INTRODUCTION
Amongst the population of Icelandic
ponies the selection of stallions and pot-
ential dams of stallions is based on a
special scoring index. The scoring index is
composed of ten traits, which can be
classified into three estimates of body
conformation and seven performance
traits. (See table 1.)
TABLE 1. Scoring index.
Multipli-
cation
Character Score factor Points
I. Confrormation:
a) Form ......... 5-10 X 2.000 = Xi
b) Proportions . . . 5-10 X 1.000 = X2
c) Legs ......... 5-10 X 2.000 = X3
ZX = Total points for conformation.
II. Traits:
a) Toelt . 5-10 X 0.833 = Yi
b) Trot . 5-10 X 0.667 = Y2
c) Pace . 5-10 X 0.833 = Ya
d) Gallop . 5-10 X 0.500 = Y>
e) Temperament . . 5-10 X 1.000 = Ys
f) Character . . .. . 5-10 X 0.667 = Ys
g) Elegance . 5-10 X 0.500 = Yi
under rider
ZY = Total points for traits
IX+I Y = Overall total score, = Index value
The conformation is scored according to a
combination of the judges’ visual assess-
ments and body measurements. The traits
are scored solely in a subjective way. The
multiplication factors or the proportional
contribution to the overall total were
decided by the breeders and Icelandic
horsemen, so as to reflect their opinions on
the economic importance of each charac-
ter.