Breeding for colour (grey).

[Meowy Catkin]

The easiest way to breed a grey, is to have one of the parents homozygous (has two copies of the grey gene) for grey. Then it doesn't matter what colour the other parent is - the foal will always grey out as the grey parent will always pass on a copy of grey to it's foals.

Lets imagine that the dam is black (homozygous) and the sire is homozygous for black and homozygous for grey (I'll stick to black as the base colour to keep everything simple).

All of the foals from this pair will be homozygous blacks but heterozygous (one copy) for grey. They will all grey out as you only need one copy of the grey gene for the horse to be a grey.

Black Black X Black Black Grey Grey


Black Black Grey
Black Black Grey
Black Black Grey
Black Black Grey




So what happens when you breed a non grey with a heterozygous grey?

You have a 50% chance of having a grey foal and 50% chance of a non grey foal.


Black Black X Black Black Grey


Black Black
Black Black
Black Black Grey
Black Black Grey




If you breed two heterozygous greys you have a 25% chance of a homozygous grey foal, a 50% chance of a heterozygous grey foal and a 25% chance of a black foal. So it is possible to have a non grey foal from two grey parents.

Black Black Grey X Black Black Grey


Black Black
Black Black Grey
Black Black Grey
Black Black Grey Grey

 

[Posie]

Interesting. So if I had a black foal who had 1 bay parent and 1 coloured parent how would that work? Or a black foal who had 2 coloured parents?

 

[elijahasgal]

Colored....patching....gene is dominant, so "hidden" gene could be for solid colour. If that is in both parents you have a 25% chance of having a solid foal. BUT there is also the chance that you will have an absoloutly minimally marked colored that looks like a solid (seen a couple of them!)

there are two base colors, black and chestnut. Bay comes with the agouti gene, which is dominant, but only shows on black. So it could be that you have not passed on the agouti, and solid gene from the other parent.

Both combinations are a 25% possiblity from mentioned parents.