Homozygous Black?

zoey829 · Sep 17, 2009

I get that Homozygous Black is dominate (EE) and the when bred the foal has to have that gene. Iknow it can carry EE, or Ee but as far as color, what does that mean in actual color? The foal will be black, or dark?? Is their a chance the foal can be red red???

targetsmom · Sep 17, 2009

Homozygous black means it cannot have a red based foal. Since an EE horse might not be black itself (could be black, bay, buckskin, etc. depending on what other genes it has), I don't think the EE affects the color of the horse itself. Our only mare that we KNOW is EE is a gray so we can't tell much from her. She is actually a silver bay frame overo, carrying the gray gene. Her foal LOOKED chestnut but I knew that was impossible - he is a silver bay, and also carries the gray gene and both tobiano and frame overo.

Joanne · Sep 17, 2009

A homozygous for black horse can NEVER have a red foal no matter what horse it is bred to. Even if it is bred to a homozygous red horse.

So it can NEVER have a chestnut, palomino, cremello.

It can have all other colors depending on what color horse it was bred to; black, buckskin, bay, grulla, dun, perlino.

You can still get all the pinto and appaloosa patterns that you would otherwise get.

Red (chestnut, sorrel) is a common color, so homozygous black horses have value in some breeding programs.

zoey829 · Sep 17, 2009

If the stallion is EE black and an appaloosa could the foals be a leopard ever?

Loess Hills · Sep 17, 2009

[SIZE=10pt]Depending upon the genetic history of the mate of a horse carrying the EE allele, the black base color can be modified by other factors (cream, silver, champagne, etc) which can dilute the coat color you see. This is the phenotype. [/SIZE]

We have a homozygous black stallion who was bred to a mare carrying the silver dilution gene nZ. The resulting filly was a beautiful palomino color. We tested her and found she was heterozygous for black, and heterozygous for silver dilution. Genetically, her genotype was actually silver bay, even though she appeared to be palomino, a red-based allele.

So, without testing, you can often be fooled by what you see, the phenotype, and what they are genetically .........the genotype.

Here's her picture:

Bunnylady · Sep 17, 2009

zoey829 said:
If the stallion is EE black and an appaloosa could the foals be a leopard ever?

The gene for black (E) and the gene(s) for appaloosa are completely separate and unrelated. This is a little like asking whether a car can have power brakes and a manual shift!

E just means that the horse produces black pigment. Other genes will determine where that black pigment will appear (if it appears at all.) The appy genes just say whether or not the horse is spotted, they say nothing about what color those spots may be. So yes, an animal that is homozygous for black can produce any appy pattern that its appy genes say it can. Of course, the odds that any of the foals will turn out to be leopard is probably inversely related to how badly you want them to be!

maestoso · Sep 17, 2009

It may help you to know that there are only 2 base colors, red and black. Every other color is made by these two colors and genes or modifiers. For example. Silver Dapple is black with the silver modifier. Bay is black with the agouti gene. Buckskin is black with agouti and cream, etc. Being homozygous for black only effects the base color, not the modifiers, at least not directly. Being homozygous for black doesn't mean the horse will only produce black foals, it just means they will only produce black based foals, which can exhibit any one of the many modifiers, depending on what the dam and sire carry. A Bay horse or a buckskin or a silver dapple, blue roan, perlino, etc, can all be homozygous for black.