Íslenskar landbúnaðarrannsóknir - 01.03.1970, Blaðsíða 28

26 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
Allele Colour or pattern Dominant to Recessive to
Ai White All None
A 6 Grey mouflon A2, A4, Ag Ai
A^ Grey Ag Ai, Ae
A3 Badgerface Ag Ai
a4 Mouflon A5 Ai, Ae
A5 No pattern None All
Tlie dominance relationship among A2,
A8 A.t and Afi was found to be such that
inhibition of pigment formation domin-
ated over pigment production.
The three allelic series were assumed to
be at three independent loci, hereafter call-
ed the A-, B- and S-locus.
The above hypothesis was published in
1960 (Adalsteinsson, 1960), but the data
on which it was based, were not published
at the same time. The present study is the
first complete account of the experimental
work on which the hypothesis was based
and the experiments carried out later in
order to test the hypothesis.
5. Grey badgerjace, grey mouflon and
liomozygous grey
The results obtainecl in the experiments
up to and including 1959 had given valu
able indications about the mode of inherit-
ance of several of the known colours and
the results and their implications aroused
considerable interest among practical sheep
breeders.
For several years prior to 1959 there liad
been an increasing interest in the produc-
tion of darkgrey lambs. The pelts of these
lambs, when slaughtered at 4—5 months of
age, were in increasing dernand in Sweden
for fur-making, and the darkgrey pelts
fetched about three times the price of ordi-
nary white pelts.
Farmers who went in for this type of
production had, however, not been very
successful, because when they mated to-
gether darkgrey parents, the progeny show-
ed a variety of colours.
When farmers who had been using dark-
grey rams were interviewed about the re-
sults, it was learned that no darkgrey rams
could be found which only gave grey pro-
geny when mated to black ewes. They all
gave a considerable proportion of black
lambs, and some gave in addition grey-
brown and brown lambs, when mated to
black ewes. The proportion of darkgrey
lambs out of this type of mating seemed
to be 50 per cent at rnost and often con-
siderably less.
On farrns where breeding of grey had
been carried out for some tirne ancl where
several grey ewes were available, the oc-
currence of lightgrey lambs with inferior
pelt colour also was found to be a pro-
blem, and this in spite of careful selection
of darkgrey animals only for breeding pur-
poses. In this latter case the proportion of
darkgrey lambs also seemed to be 50 per
cent at most, while lightgrey, black, grey-
brown, brown and various types of piebald
lambs were at least as comrnon as the dark-
grey.
The residts of tlie experiments described
so far indicated that all grey progeny out
of matings arnong grey badgerface or grey
mouflon sheep, should be liomozygous
grey.
As it would obviously be of economic
significance for pelt producers to obtain
homozygous grey rams, permission was ob-
tained to buy 25 ewe lambs and 4 ram
lambs on behalf of the University Research
Institute, Department of Agriculture.