Conundrums of Colour: A look at breeding for colours in black and coloured sheep

By Ross Manson

Note: This article first appeared in the magazine of the Black and Coloured Sheep Breeders’ Association, issue 163, June 2017. Two other articles followed on the same subject in later issues, and will be reproduced in this format in the future.

The following notes about breeding to obtain a specific colour, are my thoughts and observations made over 50 years of sheep breeding. I hope this will stimulate further observations and discussion.

xx xy xy yy = Mendelism

After over 50 years of working with sheep, it is clear to me that mathematics controls all factors of sheep breeding. Mendel theory is a fact!

Nature definitely holds sway in every aspect of an animal’s life. Nurture is a human part of nature. The only argument is, what effects the different calculations have on each other.

With the science out of the way, I can now go over to the only things most of us have an influence on, observation and experimentation. In such a huge field I will try to keep it simple.

One important thing that I have observed, in regard to breeding for colour, is that the colour of the animal’s mouth is more important than the colour of its fleece.

Colour is always recessive to white. I have observed the following colours, i.e. sheep will breed true to that colour: grey, black, brown, moorit brown and grey blue.

Grey: In a flock of seemingly grey sheep, in actual fact an animal could be any of the above colours, identifiable by the colour in the mouth. However, true grey is the dominant colour. Lambs are born with a grey or black fleece which fades to grey or almost white. In the mouth the gums are black, as is tongue.

Black: This colour is recessive to grey. The lambs are born with a black fleece, and remain black all their lives, though some fade to a greyish black. In the mouth gums are black as is tongue.

Brown Moorit: Lambs are born almost orange and can fade to almost white. The mouth and tongue retain the classic orange colour.

Brown: These sheep can be either homozygote and heterozygote. In the heterozygote sheep, the mouth and tongue are pale, almost the same colour as a white sheep. It is recessive to grey, and the lamb is brown. Because it is heterozygote it won’t necessarily breed true. The recessive homozygote version is born with very dark legs which fade in a few days. This unique colour, which I call brown violet, often fades to a pale violet or brown. The mouth and tongue are violet (or what ever colour you think it is; I am open to suggestions!)

Blue Grey : I have seen only two or three of these blue grey sheep, which have a blue grey tongue and mouth. I don’t know where this colour stands in the dominate recessive scale. The fleece colour fades.

One strange detail that I have just observed, is when a moorit is crossed with a violet sheep the progeny can have an orange mouth with pink spots I can only speculate that the two genes are of equal value.

If you cross a black with a brown you will get black, brown, or a horrible blend of both, a muddy brown, which I do not consider an attractive colour.

I have heard of cream coloured black sheep, ie a sheep with a cream coloured fleece and a black mouth, but have not seen any myself. White sheep with pink mouths are the dominant colour, and make up most of the New Zealand flock. It is confusing that they are not considered by the experts to be white but cream.

Albino sheep, which are white with pink or blue eyes are possible but are currently unknown in New Zealand. If you find one you would become famous in New Zealand!

You will notice that I have not said anything about spots, stripes, English Leicester pattern etc. I believe these overlap the colour I have described above.

As I have little experience in Merino colours I would be very happy if a breeder could tell us their experience in breeding for colour.

A final question. Are sheep the only species where the coat colour can be determined by the colour inside the mouth?