Íslenskar landbúnaðarrannsóknir - 01.03.1970, Side 10

8 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
to be of value, the criteria for grouping
must be based on phenotypic similarities,
and preferably on phenotypic characteri-
stics which are likely to have similar gene-
tic background.
The pigment observed in the slieep in
the present study can be divided into 3
colour categories, as follows:
1. Tan (rustred) pigment, wliich occurs
only in the birthcoat of lambs, and in
kemp and outercoat fibres, and in
fibres on hairy parts of the adult ani-
mal.
2. Black pigment, which may occur in all
fibre types.
3. Brown pigment, which may occur in
all fibre types.
On the basis of this classification of pig-
ment, and of the descriptions of colours
in Icelandic and Norwegian sheep by PÁls-
son (1944) and Berge (1958), respectively,
together witli personal examination of rare
sheep colours and inspection of flockbooks,
it was decided that the following basic as-
sumptions could safely be macle witli re-
gard to phenotypic classification of colours
in the Icelandic sheep.
1. Sheep could be classified as either
white or nonwhite (Plate I, 1).
2. Sheep with tan pigment should be in-
cluded in the white group, if tan was
the only pigment present (Plate I, 2).
3. Sheep in the nonwhite group showed
either black or brown (but not both)
pigment in pigmented areas (Plate I,
3 and Plate I, 4).
4. Three basic colour patterns were
known to exist, i.e. grey (a mixture of
pigmented and white fibres), badger-
face (pigmented belly, light dorsal
part) and mouflon (pigmented dorsal
part, white belly).
5. Colour patterns shown by nonwhite
sheep manifested themselves indepen-
dently of the type of pigment.
6. White markings in nonwhite sheep
could manifest themselves indepen-
dently of pigment type and colour
patterns.
B. MAIN COLOURS OBSERVF.D
Having decided on these basic assump-
tions as the cornerstones of a classification
system, the next step was to obtain in-
formation on how many phenotypes of
nonwhite sheep one would except from
independent combination of the two pig-
ment types with all possible types of pat-
tern and all possible types of white mark-
ings. It then became clear that under the
assumption of complete independence of
possible patterns among themselves and of
complete independence of white markings
among themselves, the number of colours
expected far exceeded the number of co-
lour phenotypes which had been described
up to that time within the country.
Through preliminary experimentation
and close inspection of extensive and accu-
rate flock records the conclusion was reach-
ed that the two pigment types, black ancl
brown, and the known pattern types could
result in 14 different, nonwhite main co-
lours, the occurrence og white markings in
nonwhite sheep being disregarded in this
connection. The 15th main colour was
white with or without tan pigment. A list
of these 15 main colours was given by
Adalsteinsson (1960). The conclusion was
based on the assumption that three basic
colour patterns in nonwhite sheep existed,
i.e. grey, badgerface, and mouflon pattern,
and that any nonwhite sheep would be
able to show either none, one or two pat-
terns. Since then the occurence of the grev
mouflon pattern as a separate pattern has
been established. This pattern when com-
bined with the badgerface pattern will give
two more colours, and one of these addi-
tional colours, grey badgerface-mouflon,
has been observed. This brings the total