[Sandra-A1]

For some reason I have never even thought about this....
What happens when you breed a grey to a homozygous.....for example a grey mare to a Homozygous Black stallion?

[WhisperingStar]

You will get a black.

[shell]

No matter what there is a 50%chance for gray. If the gray WAS chestnut, for example, that red gene would break the homozygous black gene on the foal so it would be hetrozygous either bay or balck, but COULD turn gray anyway.

If you crossed a homozygous gray to a homozygous black you would get a balck or bay that WOULD turn gray for sure, BUT would then be hetrozygous gray and could produce a non-gray foal.

[WhisperingStar]

This is from this website and is very interesting. I love this website because I think I just found what my boy is ( a fading black.) anyhoo this is cool.


http://www.equinecolor.com/black.html





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Non-Fading Black - Mixed Breed
©Equine Color

Black horses can be described as having black bodies and black points. Black horses without any brown or red hairs are generally harder to find than Bays or Chesnuts, this also will depend on the breed.

Black occurs in most breeds and is considered the only color in some such as the Friesian (although very rarely, Chestnut Friesians do occur). Some breeds have been specifically bred out the Black color, these include the Suffolk Punch and Haflinger.

Non-Fading Black is just as it sounds, a Black horse that does not become "sunburned" or fade from effects of sun and weather. The horse above is an excellent example of the non-fading shade. He was a working ranch horse who spent his life out in the elements. As you can see from the photo, he did not fade from sweat, saddles rubbing or weather. These foals may be born a smokey or blue-black shade. These horses only very rarely will ever fade in extreme conditions.

Fading Black - Canadian Horse
Philipuce Jack Eperle
Courtesy Jordan Lake Farms
Fading Black is a horse that fades from sun and weather. These foals are usually born a smokey ashen color, but may also be born a dark bay or brown. Mature horses usually fade to varying degrees and maintaining the rich, deep Black color requires alot of work.

Regardless of whether they will fade or not when mature, your average black foal will be a black color with lighter sooty areas along the underside of it's body. It's normal for a black foal to have light colored legs as seen in the photo below.

Fading Black - Mixed Breed
Gipsy
Courtesy Sandra Patton

Average Black Foal
Courtesy Tibbs Family Miniatures

Genetic Information

Black pigment in mammals is caused by Eumelanin (yoo-MEL-a-nin). Black is one of the base colors for horses, the other is red (Chestnut). All horses will have a black or red base color. The control for Black is located at the Extension locus and is dominant at that locus. Black horses are not capable of producing Bay foals unless the mate is a Bay or a Chestnut masking Agouti. To learn more about Agouti, see the section about Bay.

Black at the Extension locus is symbolized by "E", since it is dominant. Chestnut is also located at the Extension but it is recessive so it's symbolized by "e".

• EE means the horse is genetically (homozygous) and physically Black*
• Ee means the horse is genetically (heterozygous) and physically Black*
• ee means the horse is genetically and physically Chestnut*

*These horses are physically Black or Chestnut when there are no dilution or modifiying genes present.

Black based colors include:

Dun Dilutes

Cream Dilutes
Silver
Dilutes
Champagne Dilutes
Roan Patterns
Grullo
also called
Grulla
Smokey Black
(1 cream gene)
Smokey Cream
(2 cream genes)
Silver Dapple
also called Black or Choclate Silver
Classic Champagne
Black Roan
also called Blue Roan

Smokey Cream is the only modified version of Black that has a different appearance in single or double doses.
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The agouti is the gene that causes a bay. The a bay is a black horse with the agouti gene.

Taken from this website: http://www.equinecolor.com/bay.html

"Bay is actually a Black horse with a restrictor or modifying type gene. This locus is called Agouti and you will often hear of Bay referred to as Agouti. Agouti restricts the black pigment to the "points" of the horse, or the lower legs, mane and tail. Bay horses generally have black ear tips also."

[WhisperingStar]

Doesn't say much abouit homozygous. I would think if the horse is homozygous for black the foal would then be black, just like a black and white homozygous paint would throw a black and white foal. Homozygous as far as I know is not like a dilution gene. Such as a double dilute , on a bay horse( buckskin ) or a chesnut ( palomino ).

[Sandra-A1]

That is sort of what I was thinking...that since the graying gene is a modifier that it would still have a chance of winning out over the homozygous black...the odds depending on if the grey was Homozygous or Hertozygous.
I am surprised that I have never thought about this before...

[3WishesDun]

I think that if the offspring inherits a copy of the grey gene...the horse will go grey over time....I have read and re-read this passage from equinecolor.com...trying to think of the effects....
What a great question Sandra!

Grey is sometimes incorrectly referred to as a pattern. More accuratly Grey is a modifier. This is because Grey an ongoing process of depigmentation of the colored hairs. Grey slowly removes the pigment from the base color, other modifiers (such as Mealy & Sooty) and dilution genes (such as Cream & Dun) that make up the original color of the horse. Grey has the unique ability to mask everything including any Pinto or Appaloosa patterns. No color is safe when Grey is present, as all horses that carry the Greying gene will end up a shade of grey or white. For this reason some breeders do not like to have mares or stallions in their breeding herd.

Grey is dominant, meaning, the horse must have at least one Grey parent to be Grey and if a horse has Grey it will be shown physically. Homozygous Greys do occur, the offspring of such horses will always go Grey.

Many think that Grey is the most dominant color or it is the strongest dominant gene. This is incorrect, Grey is not more dominant than any other dominant color or pattern gene - all dominant genes are equally dominant. Grey seems to be a "very strong" gene, only because it removes all physical affects of other color factors. This does not however mean that it removes the genes that causes colors and patterns. It also doesn't mean that a horse is going to be more likely to pass along the Grey gene than the dominant gene for Bay, Silver or Cream, ect.

At times, Grey is also incorrectly referred to as a color. While somewhat correct, it can be confusing because all Grey horses have a base pigment of either red or black and depending on what other genes are present all Grey horses were another color at birth. Figuring out the base color of a Grey horse can be very time consuming and some very surprising foal colors can be seen from Grey parents. Some think that all Grey horses start out being Black. This is a myth. Any colored or patterned horse can go Grey, from Black to Cremello.



April

[Blistering Winds]

Sandra, from what I have read and learned, I would guess the foal would be either black or bay, depending on what the Gray's origional color was. And will eventually gray out.

That would be my guesstimation.

[Sandra-A1]

Thanks everybody...I was just wondering...
I have no idea why I was even thinking about this, but the question entered my strange brain...and I decided to ask...
I have seen 2 greys produce a bay foal that did not grey out at maturity so was just wondering how homozygous would work with the grey modifier.

[shell]

Originally Posted by Sandra-A1

Thanks everybody...I was just wondering...
I have no idea why I was even thinking about this, but the question entered my strange brain...and I decided to ask...
I have seen 2 greys produce a bay foal that did not grey out at maturity so was just wondering how homozygous would work with the grey modifier.

I have seen that too. Most likley, both gray parents were hetrozygous gray (They had a non-gray parent) Making it possible for the 2 non-gray genes to come together and create a non-gray foal.