If I cross a buckskin?

[Jenny]

If I cross my little buckskin pony with a TB stallion who is proven to be homozygous bay. What colours could I get? She is s dartmoore cross and I have no way of knowing what colours her parents were. Thank you.

[K~2]

You will get a buckskin or a bay.

[cj55]

Offspring Color Probability

46.88% - Buckskin
46.88% - Bay
3.13% - Palomino
3.13% - Chestnut

Great color calculator on this site, we use for paints.
http://www.animalgenetics.us/CCalculator1.asp

[Georgerz]

If the stallion is homozygous bay, how can there be any possibility of chestnut or palomino at all?

[cj55]

Hi,
If the stallion is homozygous for "Black" it can only be a bucksin or bay as a homozygous "black" cannot produce red progeny.
If I understood correct the stalllion is homozygous for "Bay"

Homozygous Agouti (AA) Agouti (Bay/Black)
Sire Color: Bay Agouti: AA Tobiano: nn
Red Factor: Ee, EE LWO: nn
Cream: nn Sabino: nn
Silver: nn Splash: nn
Dun: dd Roan: rr
Champagne: nn Gray: gg

Dam Color: Buckskin Agouti: Aa, AA Tobiano: nn
Red Factor: Ee, EE LWO: nn
Cream: nCr Sabino: nn
Silver: nn Splash: nn
Dun: dd Roan: rr
Champagne: nn Gray: gg

Details All: Data below gives the possible offspring coat colors and the probability of each determined using the given information of the sire and dam given ie: homozygous bay and a buckskin
EE/Aa/nCr = 21.0938%
EE/Aa = 21.0938%
Ee/Aa/nCr = 14.0625%
Ee/Aa = 14.0625%
EE/AA/nCr = 7.0313%
EE/AA = 7.0313%
Ee/AA/nCr = 4.6875%
Ee/AA = 4.6875%
ee/Aa/nCr = 2.3438%
ee/Aa = 2.3438%
ee/AA/nCr = 0.7813%
ee/AA = 0.7813%

I am not an expert, I just used the color calculator by inputting the data.
http://www.animalgenetics.us/CCalculator1.asp
It would be different if he is homozygous black but I suppose you can look at him for his bay color.

[Georgerz]

Well. my misunderstanding. As far as I have read, I understood that a homozygous bay or black horse (stallion or mare) could not produce chestnut offspring, like Seattle Slew or St. Simon.

[cj55]

Hi Georgerz,
After looking at the data, The sire and dam both carry a red and a dun factor, and the dam carries a creme factor so that must be where the palomino and chestnut come in? kind of interesting... I did not know a homozygous black horse could sire a palomino, they can, but they cannot sire a red horse. Best regards, cj

Homozygous Agouti (AA) Agouti (Bay/Black)

Sire Color: Bay Agouti: AA Tobiano: nn
Red Factor: Ee, EE LWO: nn
Cream: nn Sabino: nn
Silver: nn Splash: nn
Dun: dd Roan: rr
Champagne: nn Gray: gg

Dam Color: Buckskin Agouti: Aa, AA Tobiano: nn
Red Factor: Ee, EE LWO: nn
Cream: nCr Sabino: nn
Silver: nn Splash: nn
Dun: dd Roan: rr
Champagne: nn Gray: gg

[cj55]

Hi again,
Seattle Slew was EE so was surely homozygous, St. Simon sired Posthumus a gray out of a gray mare which is not a red gene so he probably was too. Interesting when you do the calculator with paints but now I have found out its pretty interesting with TB's as well! Thanks for the question that made me go look again, I still don't have a handle on how it all works but do enjoy reading on it. Enjoyed the input, cj

[Georgerz]

I understand that when a homozygous bay/black horse has a gray offspring, the other parent has to be gray.
Thanks for your research, I read it with interest.
Maybe some of the other members that have a thorough handle on the issue could explain further.

[halo]

There have been a lot of tb stallions that are homozygous bay, which means they can not produce a chestnut. Something to do with the bay gene being dominant over chestnut. BB as opposed to being Bb. I don't exactly understand why, I just understand the results. Seattle Slew and Danzig are two stallions that never produced a chestnut. Im having my suspicions that Vindication is also that way.

[xfactor fan]

Since there are two sets of genes involved in producing a bay, this can be confusing.

A bay horse is a black horse (EE, or Ee) in genetic terms a red horse is always (ee). The base coat is modified by the Agouti gene (AA, or Aa) to produce a bay. (aa) is black not bay.

So a bay horse could be AA-EE, AA-Ee, Aa-EE, or Aa-Ee. So when someone says Homozygous for Bay, are they saying the horse is AA-EE which would be Homozygous for BOTH black and Agouti, and could only produce black based horses, and would always contribute a Agouti gene.

But if the horse is Ee (carries both the black and red genes) the horse would appear Black, and if it also carried AA then it could be said to be Homozygous for Bay (agouti) but still produce a red foal.

Think of the colors as layers
First layer is Black base color
Second layer is Agouti, which pushes the black away from the center of the horse to the points.
The cream gene in one dose will lighten the existing colors to brown on the points, and tan on the body. In two doses lightens the entire horse to a pale shade
Grey overlays everything, and over time turns off the pigment in the hairs and so over time the whole horse turns white.

All of these genes live on different chromosomes and so are inherited independently.

Seattle Slew was Homozygous for black (EE) so he only produced black based offspring, but since he was brown he was also Homozygous for the non-Agouti version of the gene (aa) So any bay foals got the Agouti gene from their dams.

[summerhorse]

There is no way to know what Seattle Slew was at A without either a test or a complete (and um, accurate) list of all his prgeny and their dam's colors. He was a brown so we do know he was A__EE. I'm not sure if he ever produced a black or not, even Swale was a seal brown.

Nobody really says homozygous for bay, does the stallion owner mean homozygous for black? If they do then the stallion is EE which limits the foals to bay or black and 50% chance of getting the cream gene passed on. So as first responder said bay or buckskin.

Did the stallion get tested or are they going by progeny records? Because you have to have a lot of foals to really say that!

[Jorge]

Jenny,

Don't miss the browse the following useful article:

http://www.apha.com/breed/pdf/Perlino0201.pdf

All the Best,

[Jenny]

Hi Guys
Thank you for a response. This stallion is dark bay and funny enough is by Danzig Connection. He has 20 or more foals on the ground who are predominately dark bay with a few red bays. I think he owner says he was tested and is EE? So that might be a bit more info. My one black mare is by him and she is from a chestnut mare we have discussed before. Jenny Bug. He has never thrown a chestnut from any mare including chestnuts. Mine however is the only black mare on the ground.

[xfactor fan]

Took a quick look at the database progeny listed under Seattle Slew and with the exception of a few gr/roan foals, they are all listed as bay or dbr/br. Given the number of foals, I'd be comfortable in saying that Seattle Slew was EE, and non-bay non-bay.

And yes there is quite a bit of discussion on the genetics of non-bay. Some folks think that there are only two versions of the Agouti gene (Bay and Black) with the other versions of non bay living on some other chromosome, while others lean toward thinking there are four versions of the gene. Standard Bay, Wild Bay, Seal Brown, and Black.