NORTH AMERICAN SHETLAND KATMOGET PATTERNS AND GENETICS

By Linda Wendelboe
 

The Theory

Researchers have shown that there are at least two separate Agouti alleles that produce similar but distinct badgerface patterns in other breeds of sheep:  See Genetic Background.  One of these patterns, called Light Badgerface, is similar to that displayed by Bitterroot Katmogets (Dailley bloodlines).  The other, called Badgerface, is similar to the pattern displayed by the Katmoget offspring of Enfield Greyling semen, imported from the UK.  The theory discussed here is that the Bitterroot Katmogets (and perhaps all Dailley Katmogets) are Light Badgerface and that the Greyling Katmogets are Badgerface.  Attempts are made to trace the origin of the Dailley Katmoget pattern.

The following descriptions are paraphrased from “The Genetics of Colour in Sheep – Some Basics” by Roger Lundie in The World of Coloured Sheep, Published at the time of the 6^th World Congress on Coloured Sheep, pages 114 and 117.  The pictures are of North American Shetlands.

"Badgerface (Ab):  The brisket, belly, up around the anus and under-tail are all black (or brown).  The colour continues up the underside of the neck to the underside of the jaw.  There is black (or brown) inside the ears and a black (or brown) bar above the eyes is usually visible.  The rest of the body (where it has double coated fleece) has a white outercoat and a black (or brown) inner coat.  It is common in a number of breeds."  

"Light Badgerface (Albf):  This pattern is similar in many ways to a badgerface but with some additional lighter areas.  They have a white or offwhite body at birth with a clearcut change at the edge of the belly.  At birth, the belly looks black (or brown) with grey (or fawn) either side of the brisket, white around the navel; in rams, white around the penis and a white purse (scrotum) and in ewes, whitish in the nipple area.  The chin may appear to be dark at birth with some fine whitish fibres mixed in.  By the hogget stage (yearling), the body is virtually white and the belly grey/dark grey or (fawn/ darker fawn) with a lighter brisket, navel area, white around the penis with a white purse (scrotum) and a grayish (or fawnish) white chin.  In those with a double coated fleece, it was noted that by weaning age, the main area of the belly had changed to a lighter colour at the staple base – this was especially noticeable in homozygous individuals."
 

Part of the general colour inheritance theory set out by Adalsteinsson is that patterns without pigmentation or with areas without pigmentation will be dominant to patterns that have pigmentation (see Colour Genetics).  This means that Albf is probably dominant to Ab and could lighten or wash out the Ab pattern if the two alleles occur in the same sheep.  Additionally,  Ab paired with Ag will probably also lighten or be washed out, perhaps leaving a Moget faced sheep at maturity.  “Moget faced” is the term used to describe a Shetland that has the typical bars and light patches of a badgerface pattern but does not have the distinctive badgerface contrast between light upper body and dark chest/belly colours.  Similarly, Albf  paired with Ag  might result in a pattern that is so pale that is gets called either a Moget faced or a Katmollet sheep at maturity.  “Katmollet” is the term used to describe a Shetland with light coloured nose and jaws.

The lightest of all the Katmoget phenotypes would be AlbfAlbf with white chin, very pale belly and scrotum/nipple area.  AlbfAb which also has the white chin and light belly, scrotum/nipple area, would be lighter than AbAb but has more pigment AlbfAlbf.  Next darkest would probably be AbAb while AbAa will probably be the "darkest" of the phenotypes showing the most contrast between the colours;  both these last two would have full standard Katmoget markings.  AbAg will probably be darker than AlbfAg and the later may not show much Katmoget pattern at all.   There will be a range of pigmentation in each of the phenotypes as well. 

In the pictures below, the Shetland on the left is from the Bitterroot line of Katmogets.  He is probably AlbfAa on black.  The other two  Shetlands are from Greyling Katmoget offspring.   The middle one is probably AbAa on moorit and the one on the right in the pictures is likely AbAa on black.  Notice in particular the light chin, light belly and light scrotum in the yearling on the left in the three pictures.

There is a significant range in the amount of pigmentation in the patterns exhibited by the Dailley Katmogets.  Data is being collected to document this further. In the future, it may be possible to differentiate between distinct alleles with more certainty.

If a breeder of North American Shetlands wants to maintain dark distinctive Katmoget patterns, breeding for AbAa is probably the best bet with AbAb close behind.  Albf can produce dark markings but not with consistency and probably only if paired with a non fading solid Aa. In Shetlands, both Ab and Albf alleles can produce some colour in the upper body fleece of the sheep that remains past maturity.

Also in Shetlands, some “bronzing” (having some bronze or tan over tones on various portions) of the Katmoget pattern is thought by a number of breeders to be desirable. Bronzing may be the result of a high degree of phaeomelanin being produced.  Some people think that the BBBb genotype may produce more of this type of accent.

An interesting comparison of phenotypes will be AlbfAa to AbAg.  These may be similar enough to be confusing so that the only way to differentiate would be close examination of pedigrees and doing test breedings.  It is expected that the Ag in AbAg would washout some of the pigment in approximately the same pattern as Albf.  It is possible that AlbfAg might be mistaken for plain Ag or called Moget faced or Katmollet as the amount of pigment remaining in the pattern area may be very pale in a mature sheep.

There is another mechanism in Shetlands that "lightens" or washes out colours and patterns.  It is informally called the "modified colour gene".  The genetic basis for this mechanism is not completely understood but it occurs in solid sheep so does not seem to be related to Ag.  It may be similar in some ways to dilution.  The pigment in the wool fibres is less intense than with black and moorit, leaving a pewter colour instead of black and an amber or honey colour instead of moorit.  A number of Shetland breeders are doing test breedings and collecting data to try to work out the inheritance of this mechanism.  It may be that the modified colour gene coupled with Ab  could also give a washed out Katmoget pattern and would further wash out the Albf pattern..

©  Linda Wendelboe, 01/04/05