Íslenskar landbúnaðarrannsóknir - 01.09.1974, Blaðsíða 64

62 ÍSLENSKAR LANDBÚNAÐARRANNSÓKNIR
SUMMARY
A breeding programme for Icelandic
dairy cattle
Magnús B. Jónsson
Jón Viðar Jónmundsson
The Agricultural College, Hvanneyri
The results of a simulation analysis were
used in order to investigate the influence of
various cattle breeding practices on expected
genetic gain in the Icelandic dairy brced po-
pulation. The investigation deals with selec-
tion for one trait only, i.e. milk yield.
The optimum size of a progeny group was
found to be 20—30 daughters for a maxi-
mum genetic gain. With regard to the cost
of the breeding programme a group size of
80—100 daughters seems to be advisable.
It seems advisable to use untested sires
somewhat more than tested sires.
Expected genetic gain increases with in-
creasing semen collection from each sire.
HEIMILDASKRÁ
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Bkíksson, Ragnar, 1971. Islandsk kvægavl i nutid
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37—50.
Hinks, C. J. M., 1971. The genetic and financial
consequences of selection amongst dairy bulls
With regard to cost it seems advisable to
collect 5000—6000 doses of semen from
each sire.
It is advisable to use the two best bulls as
bull-sires in any given year, and it is indi-
cated that it may be possible to increase con-
siderably the use of sires of a beef breed
without adversely affecting genetic improve-
ment in the dairy breed.
The considerable influence of factors such
as heritability, participation in record keeping
and population size on expected results of the
breeding programme, is demonstrated.
The conclusions are discussed in considera-
ble detail, both in relation to results of stu-
dies carried out in other countries and with
regard to practices applied at present to cattle
breeding in this country.
A genetic gain of 1.0—-1.5% per year is
expected in the whole cattle population if the
breeding programme advocated in this paper
is put into practice.
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—218.
Hunt, M. S., Burnside, E. P., Breeman, M. G. og
Thomson, G. M., 1972. Inpaa of selection,
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