Íslenskar landbúnaðarrannsóknir - 01.03.1979, Side 104

102 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
ÍSLENZKT YFIRLIT.
Rannsókn á eiginleikum íslengka hestsins.
ÞORVALDUR ÁRNASON,
II. Kynbótaeinkunn.
Á grundvelli niðurstaðna arfgengis og
fylgnisreikninga, sem lýst var í fyrri grein
þessa greinarflokks, var reiknuð kynbót-
aeinkunn fyrir einstaklingsúrval. Hlut-
fallslegt mikilvægi einstakra eiginleika var
fengið með því að nota margfeldisvægi
dómstiga kynbótahrossa. Kynbótaeink-
unLÍn er þá þannig:
I = 0.481X1 + 0.102X2 + 0.596X3 +
0.589X4 + O+6IX5 + 0.762X6 +
REFERENCES — HEIMILDARRIT:
Árnason, Þorvaldur, 1976: Studies on traits in the
Icelandic riding ponies. Unpublished M.Sc.
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Arnason, Þorvaldur, 1979: Studies on traits in the
Icelandic toelter horses. I. Estimation of some
environmental effects and genetic parameters.
J.Agr. Res. Icel. Vol. 11,1—2:81—92.
Becker, W.A., 1975: Manual of quantitative genet-
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una, Pullman, Washington.
Cunningham, E.P., 1969: The relative eflficiencies of
selection indexes. Acta Agric. scand. 19: 45-48.
Falconer, D.S., 1960: Introduction to quantitative
genetics. Oliver and Boyd, Edinburgh.
Graybill, F.A., 1961: An introduction to linear stat-
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Inc., New York.
Harris, D.L., 1963: The influence of errors of par-
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Harris, D.L., 1964: Expected and predicted progress
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0.199X7 - 0.163X8 - 0.055X9 -
0.539X10
þar sem Xi ... Xio eru einkunnir fyrir
eiginleika dómstigans í réttri röð.
Leitast var við að reikna kynbótaeink-
unnir fyrir úrval byggt á afkvæmadómum
með misstórum afkvæmahópum, en
niðurstöður urðu sýnilega afar brenglað-
ar. Ástæða þess reyndist sú að erfða fer-
vika/samvika fylkið var ekki jákvætt af-
markað („positive definite“), sem leiddi af
sér tilraunir til andhverfunar á ,,singular“
fylkjum sem engar einstakar andhverfur
hafa. Stungið var upp á leið til lausnar
slíkra vandamála.
Hazel, L.N., 1943: The genetic basis for cunstruct-
ing selection indexes. Genetics, 28: 476-490.
Hazel, L.N. and Lush, J.L. 1942: The efficiency of
three methods of selection. J. Hered., 33:
393-399.
Henderson, C.R., 1963: Selection indexes and expec-
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Robinson), p. 141-163, Publ. 982, National Ac-
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errors on the efficiency of index selection and on
the accuracy of genetic gain prediction. Ph.D.
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Smith, F.H., 1936: A discriminant function for plant
selection. Ann. of Eugenics. 7: 240-250.
IVilliams, J.S., 1962: The evaluation of a selection
index. Biometrics, 18: 375-393.