ICELANDIC/SHETLAND/FINN COLOR GENETICS


5. MYSTERY OF PHENOTYPES

Now the questions begin...we all have sheep that were born a certain color and then changed. So what the heck are they? Here are some general rules...I say general because I'm taking this from the Icelandic information and my own experience which is limited in some of these colors. I'm not including much about facial markings here, because I'm not sure.

A LOCUS:
Awt
in one or both genes will be born white, may have some reddish tan spots or hairs.
Ag/Ag will probably appear to be greyish at birth on birth coat and face/legs. Will probably grow up to look white, but may have some black or brown lightish hairs or spots on face/legs. Sue Russo told me this is "mirkface" in Shetlands.
Ag/Aa will look black or brown at birth, but will have some white hairs popping out, generally on the head and tummy/scrotum may be lightening. At close inspection, the lighter greys/fawns will start to lighten at the skin when the lamb is very young, the darker grey/grey/browns may stay dark for months. Also, these sheep can stay very dark until the next spring then bingo the pigment gets turned off and they suddenly are almost white the rest of their lives. Ah, sweet mystery of the grey gene!  My guess is that you'll find the Shetland musket, fawns, emskets here.
Ab is the badgerface or katmoget.  You'll see it if your lamb is Ab/Ab or Ab/Aa. It will have a dark chin and "eyebrows" and a lighter colored body and darker tummy extending up under the tail as I recall. The Ab can hide under the Awt white. These markings and color differences do not come and go as the sheep matures or as the seasons change.
At is the  moufflon (reverse badger) gulmoget pattern. Like a wild moufflon sheep, it will have a darker body with a light colored chin and light "eyebrows" and a light tummy that extends up its rear end to under its tail. These markings and color differences do not come and go as the sheep matures or as the seasons change.
Aa/Aa will be solid black or solid moorit at birth, and may gradually over the years start to fade out a little, becoming Shetland iset.

I haven't been able to precisely correlate the genotype with the Shetland colors and markings, especially between some of the darker sheep in the Ag/Aa and the solid color sheep Aa/Aa. Is shaela grey or a faded black? Is musket a light color, or a greyish brown "mouse color" as I'm reading right now on a color list which I think comes from the Shetland Flockbook Society, and does it come from the grey gene or a fading solid color?   If anyone has experience with predictably reproducing shaela I would love for them to share it with me. Icelandic breeders may face similar quandaries.

Only thing I'm pretty sure of is that in the A locus, pigment inhibition is dominant. So if your sheep inherits a light grey (nearly white) type grey gene, it will override any darker grey gene your sheep may have inherited. With that theory in mind, if you want your greys (this includes grey/browns) to stay dark, the thought is to breed them to more dark greys or a solid color.

A word about Shetland katmoget/gulmoget. Right now I have a homozygous grey ewe with the most striking "moget" face--lots of neat stripes and bars on the face only. It will fade as the seasons change. She's not a baderface (katmoget) or even a moget face in my opinion since she changes. Same goes for some little grey/brown lambs which I've had born with light tummies, all the way up the tush. The tummies appear moufflon (shetland gulmoget) but no distinct facial markings at birth, and by first shearing the whole fleece looked pretty much the same..they might have been some areas of color variation but it was pretty much all grey.  There is thought that these variations might actually be another definable pattern emerging, in addition to the Awt, Agt, Ag, Ab, Abt,  and Aa.

B locus is pretty self explanatory. Your sheep, if it is showing color which is not hidden in by Awt dominance, is either black or brown factored. Again, the black factor can be hiding the brown. The brown is all Bb/Bb brown and cannot donate a black gene to an offspring.

S locus, so prevalent in the Shetland Foula sheep and in many Icelandics, seems hard to get for some Shetland breeders in the US. I know some of the sheep in my flock are carrying it because they have large patches of broken color and dark eyerings at birth, but because they are Ag/Ag in the agouti locus, it fades so quickly that even eyerings go away. On the other hand,  since these sheep also have really nice fleeces, it makes up for the sheep growing up and hiding the pizzazz.  Since Ss/Ss is recessive, sometimes extensive inbreeding is done to get those white markings set.  I have no quarrel with that, but breeders should always keep in mind that with extensive inbreeding or line breeding to get a particular pattern or marking, fleece quality may suffer and other heritable defects such as monorchids or endangering horns might become more concentrated.





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Copyright Lanette Scapillato 1999