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GENETIC BACKGROUND ON BADGERFACE AND
LIGHT BADGERFACE
By
Linda Wendelboe
In
the 1970s, Dr. Stefan Adalsteinsson worked out a guideline for colour
inheritance in Icelandic sheep that is now used for most Northern European
short tailed breeds, including Shetlands. One of his larger studies: “Colour Inheritance in Icelandic Sheep and Relation Between Colour,
Fertility and Fertilization” is published by The Journal of Agricultural
Research in
Reykjavik,
Iceland. In this work, Adalsteinsson identified a number of the alleles
at Agouti that determine the patterns we see in our Shetland sheep. One
of these patterns he called Badgerface – which is what Shetland breeders
call Katmoget.
This allele was recognized by the Committee on Genetic Nomenclature of
Sheep and Goats (COGNOSAG) in 1988 as Ab.
Dr. Adalsteinsson did remarkable ground work in this area and now
researchers are finding more alleles at Agouti. These produce a number
of different, distinct, repeatable patterns. Dr. Roland Sumner published his
“Expression of the Badgerface Pattern in New Zealand Longwool-type Sheep”
in the Proceedings of the World Congress on Coloured Sheep, USA, 1989. In
this work, Dr. Sumner showed the existence of another allele at Agouti
that produced a Badgerface pattern that is distinct from Ab.
COGNOSAG recognized this pattern as Albf in
1988. The following is excerpted from Dr. Sumner’s paper but uses the
term light badgerface as the pattern is now known:
“Description of Pattern: While it is postulated that both the
badgerface patterns may occur on either a black or moorit background, all
segregation trials in New Zealand to date have, because of availability of
suitable numbers of sheep of known genotype, been carried out using black
(BB) background sheep. No moorit (bb) background type badgerface sheep
have yet been reported to describe the colour shadings which would occur.
To minimize ambiguity in comparative descriptions, the badgerface pattern
is referred to subsequently as "black badgerface".
The areas of pigmentation for both the light badgerface and black
badgerface patterns are similar with only the intensity of pigmentation on
the belly and body differing. At birth, both patterns have a white to off
white body with the light badgerface's body being lightly pigmented
particularly in an area above the cervical and thoracic vertebrae while
the black badgerface has virtually no pigmentation on the body. The belly
and perianal regions are pigmented on both patterns varying from mid-grey
to black in the light badgerface and black in the black badgerface. The
patterns can however be accurately differentiated in males on the basis of
the extent of pigmentation on the scrotum and sheath and in either sex on
the extent of pigmentation on the area on the medial aspect of the hock.
These areas are consistently light grey in the light badgerface and black
in the black badgerface. The lower legs of sheep carrying either pattern
are black.
With the exception of the chin, patterning on the head of
both pattern types is similar, with a white blaze on the forehead and
bridge of the nose, white on upper lip, white around the eyes and white
edging to the ears on a black background. The light badgerface has a
white chin and the black badgerface a black chin. The belly becomes
lighter with age while other areas
of the body remain
unchanged.”
Dr.
Sumner has subsequently done test breedings that show Albf pattern
on
moorit (Bb)
sheep. He has not done any work on comparing the Light Badgerface
phenotype to the Badgerface/Ag phenotype.
In discussions with Dr. Sumner, he advises that the phenotype of AbAg
could be quite close in appearance to the phenotype of AlbfAa
or AlbfAg.
Roger Lundie has
also documented Albf
and Ab as
separate alleles:
“The Genetics of Colour in Sheep – Some Basics” by Roger Lundie in The World of Coloured Sheep,
Published at the time of the 6th World Congress on Coloured
Sheep, pages 114 and 117. He
has also shown that a third badgerface pattern, he calls Hip Spot
Badgerface, occurs in some breeds.
Pictures of Light Badgerface
and Badgerface sheep other than Shetlands can be found in the
Proceedings Of the World Congress on Coloured Sheep, USA, 1989 and in The
World of Coloured sheep, published at the time of the 6th World Congress
on Coloured Sheep.
© Linda Wendelboe,
12/04/05
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