[Patty13637]

I have a horse whos sire is Homozygous for the Black Gene but the offspring of this sire is reg bay. The offspring looks black except in summer when he fades a bit. Any chance of getting his color changed ? His dam was bay.

Thanks , Patty

[Sodapoppers]

I'm not quite following here. The gene for black is E. In a regular "fading" black horse, the gene will look like Ee. (black is a dominant color) To have a homozygous black, you must have EE. So in order to get that, both parents have to be black. If he is fading in the summer to the point where he looks a bay, my guess would be he is a Ee (not homozygous) or he is really a dark dark bay.
Was he sold to you as a homozygous black? Do you have pictures of him? Unless I am mistaken, that's not possible with those colors...

[ryu2832]

The Bay allele is dominate to Black. If the dam is bay then there is at least a 50% chance the offspring will be bay.

You would only be 'guaranteed' a black offspring if the homozygous black stallion was bred to a black or chestnut mare.

Does that answer your question?

[prettyqtrs]

Okay so sire is homozygous black (homozygous black what?-Bay? Black?) and the dam is bay(heterozygous black?).
I guess Im not sure what you are asking? Are you wondering if your horse is bay or black? If he could be homozygous black? What?

[Sodapoppers]

On second thought I am thinking I could be wrong. I'm doing some research now...hopefull someone who has a better idea of this will step up in the mean time

[ryu2832]

Reading it again, I'm not sure I got this right.

The stallion is supposedly homozygous Black (aaEE)

The stallion's offspring are all Bay?

And the offspring you have looks black most of the time, but fades to look bay?

Is your offsprings dam Bay or it was the stallion with the bay parent?

Sorry for all the questions, just want to get it right!

[prettyqtrs]

Originally Posted by ryu2832

The Bay allele is dominate to Black. If the dam is bay then there is at least a 50% chance the offspring will be bay.

You would only be 'guaranteed' a black offspring if the homozygous black stallion was bred to a black or chestnut mare.

Does that answer your question?

Just adding to your post-

Heterozygous black to heterozygous black there's a 50/50 shot on each parents of throwing the black gene. You could get a homozygous black foal if both parents threw thier black gene, heterozygous black foal if only one parents throws the black gene. And homozygous red is neither parents throw the black gene.

If you breed homozygous black to heterozygous black you are garunteed a black based foal. So you are garunteed a heterozygous black horse, and if the heteozygous black parent also throws the black gene you get homozygous black foal.

If you breed homozygous black to homozygous black you are garunteed a black based foal...and it will be homozygous black.

[Sodapoppers]

I was confused too. I read that she had a horse who was supposed to be homozygous for black, but both parents were bay. Ooops

[prettyqtrs]

Okay lets pick apart what she said peice by peice. Maybe we can get somewhere then...

"I have a horse whos sire is Homozygous for the Black Gene"
Okay so her horse's sire is homozygous black. But what color is this stallion? And is/was he genetically tested to confirm that he is homozygous black?


"but the offspring of this sire is reg bay. "
Okay...well a homozygous black horse can produce a bay...so no problem so far.


"The offspring looks black except in summer when he fades a bit. "
So her horse looks black but fades out a little over summer.


"Any chance of getting his color changed ? "
What are you wanted to change his color to? Black? Before changing his color on regstration papers, I would coat color test him to find out for sure if he is black or bay.

"His dam was bay."
Okay so the dam of her horse is a bay. Is she heterozygous black or homozygous black? That would just be letting you know if there is a better chance of your horse being homozygous black or heterozygous black. If the mare is heterozygous black..then there's a 50/50 chance of her passing that black gene onto him. If she's homozygous black, then you know your horse is homozygous black because both sire and dam are.

[ryu2832]

Help us Patty, we need you.