While all sheep will have the same base colors, agouti patterns, spots and extension possibilities, there is no breed that has all of the different alleles. I will be discussing mostly patterns found in Shetland sheep as I am most familiar with them.
BASE COLOR: All sheep will be either black or brown (moorit in shetlands). Moorit is recessive to black. there can be 3 combinations for this gene: BB Black animal, Bb Black animal, bb Moorit animal.
Agouti: the following pattern alleles are currently found in Shetlands:
- Awt (Agouti White and Tan) known as white in Shetlands. this is the most dominant pattern of them all. A white sheep will still be black or moorit underneath the white. The white allele will also cover up the second allele at Agouti so white sheep can be solid, katmoget, gulmoget etc under the white.
- Ag (Agouti gray) known as gray (black base) and musket (moorit base) in Shetlands. These sheep look very different in the heterozygous versus homozygous state. AgAg lambs are born nearly white with just a little color in the hair on their head and legs. After a few weeks these animals will look white and this is why its important to take photos of lambs. AgAa lambs will look solid, but will fade after a few months. this pattern allele only affects the wool follicles where the pigment is shut off and not allowed to be made so fleeces generally will be closer to white/silver due to this. this pattern is co-dominant to all other patterns except Awt and Aa.
- Ab (badger face) known as katmoget in Shetlands, is where the pattern is light on the top of the animal/body, but dark on the bottom of the neck, belly, legs and up to the tail. so the base color will only show on the bottom parts of the sheep. Traditionally all black based katmogets are registered as gray (SSS flocks register by color of wool!), and moorit katmoget are registered as fawn katmoget. this pattern is co-dominant with all other patterns except Awt and Aa (discussed below). So you can get AgAb, AtAb, AlbfAb, etc and each pair or dual pattern is going to express a bit differently. I hope as time allows that i will be able to add photos to these descriptions so I can help explain this. homozygous katmoget will look the same as a heterozygous AbAa.
- At (black and tan) known as gulmoget in Shetlands. This pattern was one that came about from a flock that had extension in the UK and has since sent the pattern over to the USA/Canada via Roban Dillon. This pattern is the exact opposite of katmoget, as the animal is mostly colored (black or moorit) except the bottomw of the neck, belly, lets and up to the tail are lighter! when bred together they cancel each other out. AtAt and AtAa will look the same. Gulmoget is a co-dominant pattern as well and will express with everything except Awt and Aa.
- Albf (light badgerface) is known as light badgerface in Shetlands. this pattern has been called ghost katmoget or light katmoget previously and results in several flocks, Judy in Montana and Stephen in Michigan had them about the same time as some Canadian flocks. When I saw that Jim and Brandi Chastain had a closed flock and had used Shetland Island ram genetics only, and they had some katmoget AND light badgerface pop out of their whites, I jumped on purchasing several lbf from their flock Whistlestop 1123 "Elite" and Whistlestop 1601 "Jason". these are proven to both be AlbfAa and carry solid. This pattern has hidden in the UK flock a long time as they register them still as katmoget or light katmoget, and can be dual patterned with Ag, At, Ab etc. We have been test breeding these rams to AaAa ewes to verify that it is not a dual pattern displaying. this is a very rare pattern in fine wool/kindly fleece Shetlands both in the UK and the USA. FFSSA, and then NASSA both approved this pattern for registration purposes.
- Ax (mouflon or wildtype) known as Imie in Shetlands. There are a few known Imie in the USA, and in the UK mainland. This is also the pattern on Foula, and is a Foula term. it mimics gulmoget (black and tan) but there are noticeable differences. If light badgerface is the 50% color saturation of regular badgerface (katmoget), then imie is the 50% saturation of gulmoget. Imie has some grizzling on the face and legs versus the eye flashes and darker stripes on the legs. This pattern is currently not recognized by any of the registries but is a historical pattern that breeds true. This pattern was described by Lynn Robertson, a native of Foula.
- Aeb (english blue) known as Sweep in Shetlands. This is not known in the North American flocks, but there are sweep on Foula (another Foula term) and in some of the older flocks in Wales and Cumbria. This looks like a solid sheep with tear drops. their wool sometimes in the saddle/back/sides area will lighten due to the allele being in the blue series. additionally homozygous AebAeb will look a bit different than AebAa. this is also a co-dominant allele and will have a different display with each other allele except is recessive to Awt and dominant to Aa. This pattern was described first by Lynn Robertson, a native of Foula.
- Aa (solid/self) known as non pattern. In shetlands we call these sheep black (shaela, emsket) or moorit (fawn, mioget). These sheep have no patterns and is the most recessive of all the agouti alleles. this animal (unless its spotted) will have no obvious signs of any pattern and will be a solid color.
Spotting - spotting is WHITE spots on a sheep. These are called MARKINGS and are NOT patterns at Agouti. Spotting is recessive in sheep and can be seen covering any and all Agouti patterns. Spotting does not breed true and can vary from a few white hairs to a nearly solid white sheep (that isn't Awt white). Both parents must carry spots or be spotted or one of each to produce spots.
Extension - this is not currently in the North American flock. This gene will cover up all Agouti patterns and will look like black/moorit sheep. Extension does not affect the Spotting genes. I have an article coming out in the upcoming newsletters and will post that here once its published.