MODIFIED COLOURS

CONFORMATION FLEECE HISTORY HUSBANDRY MEAT & OTHER

FIBRE WORKS FARM
SHETLAND MODIFIED SOLID COLOUR
INVESTIGATIVE BREEDING PROGRAM
2006 PROGRESS REPORT

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In 2002, Fibre Works Farm in west central Alberta imported several Shetland ewes from Judy Colvin of Bitterroot Ranch in Montana.  They were bred in quarantine to a Fibre Works Shetland ram.  Two of the lambs born out in this group in 2003 had odd colour fleeces.  That started my investigation into what we are now calling modified Shetland colours – dark brown, fawn, mioget and charcoal/pewter.  Theresa Gygi of Under the Son Farm and Gail Former of Underhill Farm, both in Indiana, are also doing similar test breedings to investigate the Mm recessive theory presented here. Other breeders may be conducting similar investigations but may be using the colour terms in a different way with different base assumptions and different results.   This is a summary of the FWF program to June, 2006.  It is ongoing and updates will be posted from time to time.

These modified colour fleeces:

  1. Are AaAa solid colours.  While they may exhibit some white fibres as the animals mature, the base colours are caused by a majority of solid colour fibres.
  2. Look like a lightened or bleached version of the basic black or moorit (brown).  They may also sun bleach at the tips but the modified colour should be apparent down to skin level in a mature sheep
  3. In lambs, may be one tone or colour and gradually change to another as the animal matures.  These modified colour changes usually happen at skin level and grow out.  For instance, char/pewter lambs are often born “off” or “flat” black.  The fleece may then take on brownish tones and finally, most of the fibres “fade” at skin level to a pewter grey.  Eye rims, nose, lips, neck ruff and hocks may change before the main body of the fleece. 

Colours that are caused solely by the presence of white fibres mixed in with black (salt and pepper) or brown (cinnamon and sugar) fibres is not considered “modified” for the purposes of this program.

In this program, “Mm” designates a hypothetical recessive allele that may bleach out the base colour of the majority of the fibres in the fleece. The work here is based on breeding together Shetland sheep thought to carry MMMm or MmMm.  We only have small sample numbers so far but it appears that MmMm may produce the mioget colour on BbBb sheep and the char/pewter colour on BBBb sheep.

It also seems likely that one form of dark brown in Shetlands may be caused by BBBbMMMm, where the Mm allows the black BB and the brown Bb to “leak” together.  One form of solid colour fawn may be BbBbMMMm where the usual moorit brown colour is lightened somewhat by the normally recessive Mm.

BBBBMMMm may also result in a modified colour phenotype but no observations have been made at Fibre Works Farm of confirmed BBBBMMMm genotypes.

There are four solid colours that seem to be representative of the range observed in the modified colour phenotypes: dark brown, fawn, mioget and char/pewter; however, seven solid colours have been delineated in the breeding program.  Black and moorit sheep may act as carriers and black and moorit progeny may be produced by carrier sheep.  In addition, several suspected carrier animals have been used that are AgAa or AlbfAa.  If Mm operates on Ag fleeces, the phenotypical effects would likely be hard to discern, given the general light nature of the Ag fleeces in Shetlands.  Where AgAa or AlbfAa animals have been used in this program, they were bred to AaAa animals and only the resulting AaAa offspring continue in the test breeding program.  For ease of reference, a list of colours and descriptions follows below.

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COLOUR NAMES AND DESCRIPTORS

VISIBONE RGB COLOUR #

ACTUAL FLEECE

1.  BLACK:  True black, no or very little brown tone.

BBB?

 

 

   ~0/0/0 to ~30/30/30

 

2.  WARM BLACK:  Black with brownish tones, most noticeable on the tips of the fleece, but evident down into the fleece as well.

Likely BBBb, may also carry Mm.