Íslenskar landbúnaðarrannsóknir - 01.03.1970, Page 9

COLOUR INHERITANCE IN ICELANDIC SHEEP 7
5. Identification of individuals
On the farras where the data for the
present study were collected all the lambs
are eartagged, usually with a numbered
aluminium eartag, shortly after birth. The
nurnber on the eartag is entered into the
record book together with the eartag num-
ber of the dam. At the same time the sex
and the colour of the lamb is recorded.
Stillborn lambs on these farms have also
been recorded and their sex and colour de-
scribed.
The lambs which are kept for breeding
usually have their original eartags replac-
ed in early winter by permanent eartags
with the flockbook number of the indivi-
duals. At that time the new flockbook
numbers are recorded together with the
parentage of the lambs in question.
6. Shearing time
The main lambing season lasts for about
3 weeks, the ewes not having lambed by then
mainly being those which dicl not conceive
at the first mating. These ewes may some-
times be put on uncultivated homeland
pasture and will lamb there without super-
vision. The records of number of lambs
per ewe and sex and colour of larnbs are
then made when the sheep are gathered
for shearing of the ewes, which takes place
in late June or early July.
During the shearing gathering the lambs
on the experimental farm Hestur have
been weighed and their weight gain from
birth to shearing calculated. At that gather-
ing the colour description of some of the
lambs has been checked and obvious mis-
takes corrected.
7. Autumn records
In late September the sheep are gathered
from the mountain pastures and taken to
their home farms. There the lambs intend-
ed for breeding are selected and all the
remaining lambs slaughtered, usually di-
rectly off the range.
While the inspection and selection of
lambs for breeding is being carried out,
some check will automatically be made on
the colours of the lambs, and any obvious
mistakes which have not been detected
earlier may be corrected at this time. The
corrections made at shearing time and dur-
ing the autumn handling of the lambs in
the present study have been relatively few.
CHAPTER II
Colour descriptions
A. BASIS FOR CLASSIFICATION
Several of the colours of the Icelandic sheep
have previously been described by Pálsson
(1944), and his descriptions formed a valu-
able starting point for the present work.
It was felt, however, that for a thorough
genetic study of the colours a more system-
atic approach to the description was need-
ed.
In order to develop a system for a com-
plete description of the colours within a
breed of sheep, one must have a fairly
compreliensive a priori knowledge about
what colours or colour combinations are
likely to occur in the population to be de-
scribed.
Any system used for such description
should take into account all possible ways
of grouping the colours. For the grouping