Íslenskar landbúnaðarrannsóknir - 01.03.1979, Síða 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 +
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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.
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