Help! I cant im trying to breed a brown dun!

Hi! I've tried twice now to breed a brown dun foal out of my brown dun Mare, even when I bred her to a brown dun stallion she threw a red dun like her last foal. I can't figure out the genetics code thing can someone please help me? This is her:

http://www.equiverse.com/horse.php?id=400850

It's a 50/50 chance as she's heterozygous for the extension gene, hence why she can throw chestnut based foals when bred to another Ee. You can increase your chance of breeding a brown dun foal by breeding to a horse with an EE AtAt DD genotype.

With her last breeding (assuming it's this foal) you had these possibilities:

[dam] Ee AtAt Dd x [sire] Ee Ata Dd

= EE AtAt DD (brown dun)
= Ee AtAt DD (brown dun)
= EE Ata DD (brown dun)
= EE AtAt Dd (brown dun)
= Ee Ata DD (brown dun)
= Ee Ata Dd (brown dun)
= Ee AtAt dd (brown)
= Ee Ata dd (brown)
= ee AtAt DD (red dun)
= ee Ata DD (red dun)
= ee AtAt Dd (red dun)
= ee Ata dd (chestnut)

So there was 50% chance of a brown dun occurring, 25% of red dun, 16.7% chance of producing a brown and 8.3% chance of throwing a chestnut.

i believe these are correct it's too early in the afternoon for genetics for me xD

That's pretty close, Maple, but you forgot that some of those combinations (Ee and Dd) have double the chance of happening than their homozygous counterparts. So, with correction for that, these are the percentages:

56.25% brown dun
18.75% brown
18.75% red dun
6.25% chestnut

So, essentially, you did make a pretty smart match for trying to get a brown dun - you had over a 50% chance of getting one, but you lost the gamble, twice. Sometimes that happens.

With the genetics, you've got three factors going on, Extension, Agouti, and Dun. I'm going to start by explaining Extension.

1. Extension has to do with whether a horse can grow black hair or not. It's called Extension because it means that the black pigment from the horse's skin will extend into the hair when it carries this gene. E means that the horse can have black hair, and e means that it cannot, and will default to red instead. E is dominant to e, which means it will overpower e. So EE and Ee will give the ability to grow black hair, and ee will never grow black hair and will be chestnut.

2. Next comes Agouti, which determines where that black hair will grow. It is a little more complicated than Extension, because it has four options instead of two. They each have a different level of dominance. Agouti will only show up if you have at least one E gene, because it doesn't matter how black is restricted if there is no black.

A+ is Wild Bay, which is the most dominant. This restricts black to the mane, tail, legs, and ears. In Wild Bay, the black on the legs is pretty minimal, and the red coat can sometimes be a little paler. Sometimes there is an almost dun-like dorsal stripe. If a horse carries the A+ gene with the E gene, they will always be Wild Bay, no matter what their other Agouti gene is.

A is Bay, which is recessive only to Wild Bay. Like Wild Bay, the black is restricted to the mane, tail, and points, but the black will extend much further up the legs. E?/A+A will always be Wild Bay, but E?/A with any other Agouti gene will be Bay.

At is Brown, which is only dominant to Black. Both A+ and A will overpower it and cause it not to show. Brown horses will be near-black to dark brown, with black points, and red or tan areas around the muzzle and eyes, and on the thin skin near the legs.

a is Black, and is the most recessive Agouti gene. This means that the black pigment extends to all the horse's hair. The only way to have a black horse is to have an E Extension gene and aa Agouti.

3. Dun is pretty straightforward. D is dominant, and will always produce a dun horse. Two recessive genes, dd, means that the horse will not be dun.

With your horse pairing, both your horses are Ee for Extension. That means the foal has one chance of being EE (black pigment), two chances of Ee (sire's E and dam's e, or sire's e and Dam's E, and also produces black pigment) and one chance of ee (red pigment only.)

Both of your horses are brown, but one of them carries the Agouti gene for black. However, because brown is dominant to black, and there is no chance for the foal to be aa, every time your foal is EE or Ee, it will be brown.

This leaves you with three out of four foals brown, and one out of four chestnut.

Dun is like Extension - both your horses are Dd, so you have one chance of DD and two of Dd (all dun) and one chance of dd (no dun.)

So, if three out of four foals from this pairing will be brown, three out of four of the brown foals will be dun.

So, yeah, a pairing that should have a very good chance of producing brown dun, but you managed to hit ee twice in Extension, so very poor luck for you.

If you wanted to ensure a brown dun horse every time, at least one of the parents should be EE, one should be AtAt (and neither should have any A+ or A), and one should be DD. It doesn't matter if all three are on one horse, or if they are spread between the two horses, but that will ensure that the foal will be brown dun without fail.

But the combination you have is honestly a pretty good one, so if you can, I would continue to match the pair until you luck out.

Thank you both so much you've managed to explain I in a way I can understand (as long as I have this page in front of me as a reference haha). Eventually ill get my brown dun foals :)