Íslenskar landbúnaðarrannsóknir - 01.03.1970, Síða 34

32 ÍSLENZKAR LANDBUNAÐARRANNSÓKNIR
additional indication that the genes for
badgerface and grey are allelic to each
other and both allelic to white.
The results shown in table 7 are also in
agreement with the hypothesis that the
pattern genes are allelic to the gene for
white. Three of the rams in table 7 give
nonwhite progeny showing the gene for
grey, ancl the fourth nonwhite progeny
showing the mouflon gene. All the non-
white progeny in table 7 thus show only
the pattern genes their grandsire carried,
and no other pattern genes have come into
the picture from the white darns of the
sires in table 7.
The results shown in tables 6 ancl 7 must
therefore be regarded as a proof that the
pattern genes are allelic to the gene for
white.
The experiment with the 4 white sons
of ram No. 01097 was also intended to
throw light on another aspect of the colour
inheritance, i.e. which genes for colour
would be found to be segregating in white
sheep which had a high probability of
being homozygous white.
As seen from table 7, rams No. 01119
and 01120 have carried the gene for black
pigment, while rams No. 01117 ancl 01118
have been homozygous for brown pigment.
This shows that genes for botli black
and brown pigment can be found hyposta-
tic to the gene for white. It is of interest
to note in this connection that rams 01118
and 01119 were twins out of ewe No.
01486. As No. 01118 was homozygous and
No. 01119 heterozygous for the gene for
brown pigment, it is clear that ewe No.
01486 has been heterozygous with respect
to pigment, while rnost likely homozygous
for the gene for white.
Ram No. 01097 was liardly testecl at all
with respect to recessive white markings as
he was only mated to one ewe known to be
heterozygous for white markings. He pro-
duced no progeny showing white markings.
The results from testing liis sons with
respect to white markings are shown in
table 8.
From table 8 it can be seen that only
one of the rams, No. 01119, has been
proved to carry genes for white markings.
The test is based on only 3 progeny out
of dams homozygous for white markings,
and all these 3 lambs showed white mark-
ings. It can therefore not be decicled from
this test whether the ram was homozygous
or heterzygous for white markings. Of the
other rams, only No. 01117 was tested to
any considerable extent, and he was shown
to have a probability of less than 0.031 for
carrying the gene for white markings. All
the above conclusions are based on the as-
sumption that white markings are due to
a single recessive gene in homozygous
condition.
Frorn the tests with respect to the genes
for white markings, no conclusions can be
drawn regarding their presence or absence
in homozygous white sheep in general.
Ram No. 01116, a black badgerface brecl
from grey badgerface parents, was expect-
ed to be homozygous for the gene for
badgerface. When mated to black ewes he
produced 10 lambs, all black badgerface,
and no lambs of other colours.
This ram showed rather clearly the head
markings which Roberts (1924) and
Wriedt (1924) regarded as characteristic
features of the badgerface pattern. These
markings may have been more pronounced
in ram No. 01116 than usually found in
heterozygous badgerface sheep. The ram
also showed limited amount of black
underwool on the upper part of the body,
a feature which possibly could be a result
of the homozygosity of allele A3. These
features were in no way conspicuous, how-
ever, and it must therefore be left an open
question whether any visual distinction
can be made between homozygous and
heterozygous badgerface animals.