Íslenskar landbúnaðarrannsóknir - 01.03.1979, Page 88

86 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
TABLE 2.
A-nalysis of Variance and Covariance.
Source of
Variation DF E(ms) or E(Cov).
Sire S-1 (TÍ+K2S(i:a) +K3*(a)
Individual/Sire Ö-S cr?+Kií(i:A)
Year Y-1 ití+Kqif
Residual N-O-Y-l (T?
where: S = number of sires
Ö = number of oífspring
Y = number of years
N = number of records
K, Ki = coefficients calculated according to
Harvey (1960).
performed several times using a different
number of records the Ki take different
values.
In the first run of Model (2), only rec-
ords containing complete information on
the ten traits included in the scoring index
were used.
All records where number of offspring
per sire did not exceed three were exclu-
ded from the analyses in this and all subs-
equent runs.
One of the traits involved, pace, was not
performed at all by several of the ponies
actually judged. They therefore obtained
a score of 5.0 for that trait. This obviously
causes markedly skew distribution of me-
asurements. For estimation ofgenetic and
phenotypic parameters concerning pace,
those records containing a score less than
6 were eliminated before the second run
on model (2).
In the third run only those records
containing complete information on the
four body measurements in addition to the
ten traits were used.
Finally, only records on females were
included to estimate the genetic paramet-
ers. Data were not adjusted and the effect
of age added into model (2). Information
about number of records, number of
offspring, number of sires and value of Ki
for the four separate runs on model (2) is
to be found in table 3.
Estimation of heritability and correlations
The heritability, genetic correlations and
phenotypic correlations were estimated
by use of a standard form of procedure
(Falconer, 1960; Becker, 1975).
The standard error of the heritability
estimates was calculated from a formula
given by Falconer (1963) and the stan-
dard error of the estimated correlation co-
efficients were calculated from the form-
ula of Hammond and Nicholas (1972).
TABLE 3.
Numerical description of four runs on Model (2).
No. No. No.
Runs records offspring sires Ki K2 K3
Firstrun ................. 1 208 1 088 108 1.0082 1.1819 10.5387
Second run ............... 959 851 107 1.0981 1.1920 8.3902
Third run ................ 1 068 976 108 1.0713 1.1501 9.2700
Fourth run* .............. 817 717 105 1.0822 1.1904 7.2037
Effect of age included in the model.