Chestnut v Grey genes - the colour lottery

[Kyrie]

I have put my liver chestnut mare to a grey. The stallion is by a bay out of a grey mare.

My broodmare in question is by a liver chestnut, mare unknown. My broodmare (before I purchased her) was put to a bay and threw a chestnut, then when put to a bay, threw a bay.

I never managed to get my head around the colour genes and what the possibilities are of what I am going to get - is anyone able to assist?

Many thanks in advance
:)

[Astraled]

There's a 50% chance your foal will be gray. Further than that, you'd need to know what color the stallion was at birth.

[Erin Pittman]

Right - think of gray as a modifier. The horse is born with a set of genes that codes for it's coat color. In the case of the gray, they have, in addition to those genes, another gene that causes the coat color to fade to gray with age. Because your mare is a chestnut, you can only get chestnut genes from her (no black and no gray). Your mare could carry one or two copies of the bay gene which you wouldn't know without doing a genetic test since bay "hides" in chestnut horses. The sire, since one of his parents was not gray, carries only one copy of the gray gene which is where Astraled got the 50% gray. So, depending on what the color genes are in the sire, you could have:
chestnut (50% gray)
bay (50% gray)
black (50% gray).
Clear as mud?
Check out http://www.equinecolor.com for some good information on color.

[eqsiu]

Without knowing the base color of the stallion you're unlikely to get any info on possible colors. Unless he was chestnut, then the foal will be chestnut with a 50% chance of going grey.

And even knowing his color, without testing you can't know what genes he has, exactly.

[pintopiaffe]

has the stallion ever thrown non-grey foals?

Grey can be homozygous as well.

[eqsiu]

has the stallion ever thrown non-grey foals?

Grey can be homozygous as well.

SHe said the stallions sire was bay.

[bornfreenowexpensive]

ok...I think I get it. I bred a dark brown mare to a grey stallion. I know he is not Homozygus. So no matter what...I have a 50% chance of a foal going grey. If the sire was born a chestnut (not sure...just throwing it out there)....I could get a chestnut, bay or black foal....that has a 50% chance of going grey.

[summerhorse]

ETA: Oops I see now the mare example is dark brown. In which case yes it could be ANY color at all, no way to tell without having DNA results or a good big foal sample from s/d and grandparents.

Yes any foal by the heterozygous grey has 50/50 chance of grey/not grey.

If the sire is chestnut under the grey and bred to the original liver chestnut then the foal will be base chestnut. If the sire is black or bay under there than the foal could be bay, black OR chesnut based depending on the actual status of the As and Es available! You could color DNA test the mare and foal (when born) and go from there for future breedings. You could maybe convince the stallion owner to test too if you can show him that people making their breeding decisions iwth an eye for color (what they like or don't like) might be more likely to use his stallion if they know what he carries (don't mention they could discard him too though for the same reasons! =) But by having the mare and foal tests you can often figure out the stallion by what is or isn't shown.

[Kyrie]

Cheers all, muchly appreciated :)

All will be revealed this time next year :lol:

[DoubleClick]

I find all of this so interesting. My grey mare, who was born dark, dark bay was bred to a bay stallion in 06 who has a chestnut dam. Looking at my mare's pedigree, her sire is bay, as is his sire, but I'm unsure about her sire's dam. My mare's dam, I believe, has a bay base color and never produced a chestnut, even when bred to a sire that regularly produces chestnut. But, my mare, when bred to the same stallion as her dam produced a chestnut going grey. Even the farm manager who stands the stallion was shocked at the color when she came to see my filly. Does anyone know any of the horses on this pedigree that are not marked for color? I've been curious to see just how many chestnuts are in there to sort of try to map out where the chestnut genes may have come from, although I realize that it's somewhat random. I see where the sire's chestnut comes from, but am curious about the dam's side. It seems to me that we had a very small chance of getting a chestnut, but my genetics knowledge isn't that great.

Sorry to hijack thread, but this is something that I mull over a lot.

http://www.allbreedpedigree.com/regan+f

[BelladonnaLily]

ok...I think I get it. I bred a dark brown mare to a grey stallion. I know he is not Homozygus. So no matter what...I have a 50% chance of a foal going grey. If the sire was born a chestnut (not sure...just throwing it out there)....I could get a chestnut, bay or black foal....that has a 50% chance of going grey.

I don't think so.

If your mare is chestnut, and the stallion was born chestnut,then the resulting will either be chestnut or gray. No chance at all of bay or black.

I am a little confused about Erin P.'s statement about bay "hiding" in a chestnut horse. I may be wrong but I didn't think chestnuts could carry any black genes at all :confused:

edited to add: wait, is liver chestnut genetically the same as chestnut, or is it genetically black/bay? That would make the above statement by the OP correct.

[BelladonnaLily]

OK, read again for comprehension. I thought bornfree was the OP but now I see I read 2 different posts. OP will get chestnut or grey. bornfree could have chestnut, bay, black, grey. Whew. Next time I'll READ the posts first :lol:

[bornfreenowexpensive]

OK, read again for comprehension. I thought bornfree was the OP but now I see I read 2 different posts. OP will get chestnut or grey. bornfree could have chestnut, bay, black, grey. Whew. Next time I'll READ the posts first :lol:


LOL sorry...I'm like the OP though and never really have wrapped my brain around it...but thanks to this thread I think I get it now. Basically lord knows what I will get with my combo until next year! I've got my fingers crossed for drk brown but will be happy with 4 legs and healthy;)

[summerhorse]

I find all of this so interesting. My grey mare, who was born dark, dark bay was bred to a bay stallion in 06 who has a chestnut dam. Looking at my mare's pedigree, her sire is bay, as is his sire, but I'm unsure about her sire's dam. My mare's dam, I believe, has a bay base color and never produced a chestnut, even when bred to a sire that regularly produces chestnut. But, my mare, when bred to the same stallion as her dam produced a chestnut going grey. Even the farm manager who stands the stallion was shocked at the color when she came to see my filly. Does anyone know any of the horses on this pedigree that are not marked for color? I've been curious to see just how many chestnuts are in there to sort of try to map out where the chestnut genes may have come from, although I realize that it's somewhat random. I see where the sire's chestnut comes from, but am curious about the dam's side. It seems to me that we had a very small chance of getting a chestnut, but my genetics knowledge isn't that great.

Sorry to hijack thread, but this is something that I mull over a lot.

http://www.allbreedpedigree.com/regan+f


Chestnut can be carried for generations in a bays and blacks (and greys which are often not identifiable for base color at all, many are born black at birth when genetically they may be bay or chestnut). There are more than enough chestnuts in each side of the Hanov. filly's pedigree that her being chestnut is not unusual at all.

I think what Erin P. meant was that chestnut can hide AGOUTI (the presence or absence of which determines if a horse is bay (A__) or black (aa). Agouti does not affect red at all so a chestnut can be AA, Aa, aa and you have no way of knowing unless you test or breed a chestnut to a known black base (aaE__) and get a bay base!

[RiddleMeThis]

I am a little confused about Erin P.'s statement about bay "hiding" in a chestnut horse. I may be wrong but I didn't think chestnuts could carry any black genes at all :confused:The gene that cause bay is A or Agouti. It only effects black pigment so if a chestnut horse has A you wil not see it. It can hide on a chestnut for a long time. Chestnuts can even be homozygous for bay as well
edited to add: wait, is liver chestnut genetically the same as chestnut, or is it genetically black/bay? That would make the above statement by the OP correct.

Liver chestnut is (as far as we) the sameas regular chestnut. There is a thought however that there is a seperate gene or genes that cause chestnuts to be liver chestnut.

[not again]

Chestnut stallion (his parents both chestnut) to Gray mare (her sire gray, her dam bay) produced (a) gray filly (b) black colt (c) gray colt.
No help there!;)

[RiddleMeThis]

Chestnut stallion (his parents both chestnut) to Gray mare (her sire gray, her dam bay) produced (a) gray filly (b) black colt (c) gray colt.
No help there!;)

Well the chesnut stallion is ee and either aa or Aa. The gray mare is Gg either Ee or EE and Aa.

[Erin Pittman]

I am a little confused about Erin P.'s statement about bay "hiding" in a chestnut horse. I may be wrong but I didn't think chestnuts could carry any black genes at all :confused:


Yes, as RiddleMeThis stated, I was referring to the Agouti gene. It's true that chestnut horses carry no black genes - they have two copies of the recessive form of the Extension gene, which - in it's dominant form is black, so only one copy would be needed for the horse to be black. The gene that causes bay however, is a completely separate gene from the one that causes black (in a different location on the DNA). Since it only affects black hair on the body - causing it to turn brown - it doesn't have any effect on hair that's already red. That's what I meant by bay "hiding" in chestnut horses. It's there, but doesn't show up in the phenotype (outward appearance of the horse).

[Waterwitch]

(and greys which are often not identifiable for base color at all, many are born black at birth when genetically they may be bay or chestnut)

A chestnut or bay horse carrying the grey gene, does, with subtle shading effects, still appear chestnut or bay at birth...not black. It does seem like the pigment in some grey horses darkens before they start greying out completely, but the genetic base color of greying chestnut and bay foals is pretty obvious unless there is another color modifying gene on the playground :)

[BelladonnaLily]

[QUOTE=RiddleMeThis;2940443]The gene that cause bay is A or Agouti. It only effects black pigment so if a chestnut horse has A you wil not see it. It can hide on a chestnut for a long time. Chestnuts can even be homozygous for bay as well

QUOTE]

Ahhhh, okay. NOW I think I get it. The agouti can be carried by a chestnut...I had it in my head that she was referring to the black gene being carried by a chestnut. I get it now (lightbulb finally comes on).

Thanks Riddle and Erin P. for clarifying. Every time I think I finally have this color thing down, I miss it again. :no: I SO want to answer someone's question one day and be right :lol: