# Breeding a homozygous black/white to a homozygous red/dun?



## NdAppy (Apr 8, 2009)

On the stallion do you mean just red (chestnut) with dun, or dun (bay with dun)? And homozygous for the dun gene?


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## Citrus (Feb 26, 2010)

Coat Color Calculator​ 


Shown below are the possible offspring coat colors and the probability of each determined using the given information of the sire and dam. Accuracy of the calculations are increase when more genetic information is known of the parents.

*Sire Color: Red Dun Tobiano *Agouti:​*aa, Aa, AA*Tobiano:​*TT *Red Factor:​*ee*LWO:​*nn*Cream:​*nn*Sabino:​*nn*Silver:​*nn*Splash:​*nn*Dun:​*Dd*Roan:​*rr*Champagne:​*nn*Gray:​*gg*
*Dam Color: Black Tobiano *Agouti:​*aa*Tobiano:​*TT *Red Factor:​*Ee, EE*LWO:​*nn*Cream:​*nn*Sabino:​*nn*Silver:​*nn*Splash:​*nn*Dun:​*dd*Roan:​*rr*Champagne:​*nn*Gray:​*gg*

*Details: Grullo Tobiano*
Ee/aa/Dd/TT = 16.6675%


*Details: Black Tobiano*
Ee/aa/TT = 16.6675%


*Details: Bay Tobiano*
Ee/Aa/TT = 16.6675%


*Details: Bay Dun Tobiano*
Ee/Aa/Dd/TT = 16.6675%


*Details: Red Dun Tobiano*
ee/Aa/Dd/TT = 8.3325%
ee/aa/Dd/TT = 8.3325%


*Details: Chestnut Tobiano*
ee/Aa/TT = 8.3325%
ee/aa/TT = 8.3325%

*Details: All*

Ee/Aa/Dd/TT = 16.6675%
Ee/Aa/TT = 16.6675%
Ee/aa/Dd/TT = 16.6675%
Ee/aa/TT = 16.6675%
ee/Aa/Dd/TT = 8.3325%
ee/Aa/TT = 8.3325%
ee/aa/Dd/TT = 8.3325%
ee/aa/TT = 8.3325%

*Offspring Color Probability* 

16.67% - ​*Grullo Tobiano *16.67% - ​*Black Tobiano *16.67% - ​*Bay Tobiano *16.67% - ​*Bay Dun Tobiano *16.67% - ​*Red Dun Tobiano *16.67% - ​*Chestnut Tobiano *


















Time = 0.109375 sec 


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## Citrus (Feb 26, 2010)

*Offspring Color Probability* 

8.33% - ​*Grullo Tobiano *8.33% - ​*Grullo *8.33% - ​*Black Tobiano *8.33% - ​*Black *8.33% - ​*Bay Tobiano *8.33% - ​*Bay Dun Tobiano *8.33% - ​*Bay Dun *8.33% - ​*Bay *8.33% - ​*Red Dun Tobiano *8.33% - ​*Red Dun *8.33% - ​*Chestnut Tobiano *8.33% - ​*Chestnut *

This was for a red dun stallion and black tobiano mare... the other was tobiano for both parents....


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## sunedee (Aug 12, 2008)

Is there such a thing as homozygous dun? I'm so not experienced with color stuff either!


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## NdAppy (Apr 8, 2009)

Yes there is.  It just means that horse is carrying two copies of the dun gene instead of one.


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## sunedee (Aug 12, 2008)

^How is it expressed? Or do you just have to test for it?

So the OP's mare (homozygous for tobiano and black) bred to a stud that's homozgyous for dun you'd have to get a grullo tobiano right? Grullo is dun expressed on black, right? Thanks!!

Sorry for hyjacking the thread!!


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## APHAforlife (Mar 2, 2011)

Bahaha thank you guys...I didn't realize that there were so many possibilities! If I do end up breeding her in the future, I have a gorgeous bay stud in mind...I would like to believe that her baby would looks as much like her as possible  Thanks so much for all of the help!


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## sunedee (Aug 12, 2008)

Your mare is gorgeous!! I love the speckles on her back. 

My black and white tobi is roany on his sides so he looks all smudged. Not that you could really tell with all the mud ...


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## NdAppy (Apr 8, 2009)

Sundee - A homozygous dun will express exactly the same as a heterozygous dun. The only way to know for sure is to test.


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## NdAppy (Apr 8, 2009)

APHA - you said she has tested homozygous for black and tobiano. Did you have her tested for agouti (bay) as well? Her pictures in your "barn" are making my suspect the possibility of brown.


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## MacabreMikolaj (May 9, 2009)

sunedee said:


> ^How is it expressed? Or do you just have to test for it?
> 
> So the OP's mare (homozygous for tobiano and black) bred to a stud that's homozgyous for dun you'd have to get a grullo tobiano right? Grullo is dun expressed on black, right? Thanks!!
> 
> Sorry for hyjacking the thread!!


Yes, although a bay dun tobiano is also possible. Being homozygous for black simply means the horse can never produce/sire a chestnut. However, the chestnut dun sire could be carrying agouti which could then pass to the foal and produce a bay dun tobiano. The only way to guarantee a black or grullo foal would be to have both horses homozygous for black and also homozygous for dun in the case of a guaranteed grullo, or else ensure that the chestnut dun sire was not carrying agouti.

Clear as mud right? :lol:

EDIT - NDAppy rasied a good point, about a homozygous black horse not necessarily being black. A bay horse can be homozygous for black.


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## lilruffian (Jun 28, 2010)

Not too sure but i know a lady down the road that bred Paints and she had a gorgous stud who was the same as your mare, Homozygous for b&w as well as Tobiano & she also had a homozygous red dun mare (beautiful QH) and every time they were bred together, which i believe was a total of 3 times before the mare was sold it resulted in a solid red dun just like the mom. 
Only difference is that the foals had socks & some facial markigns while the dam was completely solid.


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## MacabreMikolaj (May 9, 2009)

lilruffian said:


> Not too sure but i know a lady down the road that bred Paints and she had a gorgous stud who was the same as your mare, Homozygous for b&w as well as Tobiano & she also had a homozygous red dun mare (beautiful QH) and every time they were bred together, which i believe was a total of 3 times before the mare was sold it resulted in a solid red dun just like the mom.
> Only difference is that the foals had socks & some facial markigns while the dam was completely solid.


That's actually impossible. If the sire was homozygous for black, it's impossible to have a red based foal result from the mating.


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## NdAppy (Apr 8, 2009)

lilruffian said:


> Not too sure but i know a lady down the road that bred Paints and she had a gorgous stud who was the same as your mare, Homozygous for b&w as well as Tobiano & she also had a homozygous red dun mare (beautiful QH) and every time they were bred together, which i believe was a total of 3 times before the mare was sold it resulted in a solid red dun just like the mom.
> Only difference is that the foals had socks & some facial markigns while the dam was completely solid.


If the sire was actually the sire and is truly homozygous black and homozygous tobiano... A red foal is not possible. A minimal tobiano _is_ possible (i.e. little white).


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## sunedee (Aug 12, 2008)

MacabreMikolaj said:


> Yes, although a bay dun tobiano is also possible. Being homozygous for black simply means the horse can never produce/sire a chestnut. However, the chestnut dun sire could be carrying agouti which could then pass to the foal and produce a bay dun tobiano. The only way to guarantee a black or grullo foal would be to have both horses homozygous for black and also homozygous for dun in the case of a guaranteed grullo, or else ensure that the chestnut dun sire was not carrying agouti.
> 
> Clear as mud right? :lol:
> 
> EDIT - NDAppy rasied a good point, about a homozygous black horse not necessarily being black. A bay horse can be homozygous for black.


 
Thanks!! I didn't know that a bay could be homozygous for black! Is there such a thing as homozygous for agouti? I really enjoy learning about this stuff but there's sooo much, lol. Thanks again.


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## NdAppy (Apr 8, 2009)

Yes there is a thing as homozygous agouti.  There are actually three agoutis. A (bay), At (brown), and A+ (wild bay).


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## sunedee (Aug 12, 2008)

How are the different agoutis inherited? My youngest is a wild bay. Dam is flaxen sorrel and sire is a bay dun. I think his sire must be homozygous for some sort of agouti because all of his foals are either black, bay, grulla or dun. Or will agouti on black give you a bay I guess? I'm confused ... lol.


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## MacabreMikolaj (May 9, 2009)

Well, you have to consider that a "bay" is just a black horse with the agouti gene. Genetically, it's still a black horse, same as any other black horse. It just adding a modifying gene that alters the state of it's color. Sort of like a grey horse - grey itself is not a color, it's just a modifier, that grey horse is still genetically a different color underneath.

It's definitely fascinating, I love equine color and what we know about. The more you learn about genetics, the more you'll actually look at equine color being layered like an onion. It's like, if I think about a perlino, I can actually visualize the black horse standing in a field, and then being painted with "agouti" to become a bay, and then being painted with a cream gene to become a buckskin and then being painted with another cream gene to become a perlino!


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## MacabreMikolaj (May 9, 2009)

sunedee said:


> How are the different agoutis inherited? My youngest is a wild bay. Dam is flaxen sorrel and sire is a bay dun. I think his sire must be homozygous for some sort of agouti because all of his foals are either black, bay, grulla or dun. Or will agouti on black give you a bay I guess? I'm confused ... lol.


Yep, if he's sired a black foal, then it could be likely he's homozygous for black but not agouti. He'd have to sire ONLY browns, bays or wild bays to be homozygous for agouti. However, if he's homozygous for agouti, but not black, he could also sire chestnut foals that will carry agouti (chestnuts cannot display agouti physically, but they can carry it).


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## APHAforlife (Mar 2, 2011)

sunedee said:


> Your mare is gorgeous!! I love the speckles on her back.
> 
> My black and white tobi is roany on his sides so he looks all smudged. Not that you could really tell with all the mud ...


Awe, thank you! Those pics are really old, from the summer that I rescued her. I am on a different computer since mine is shot right now so I haven't had the chance to upload any recent pics. She has gained about 200# and is a bit more filled out...she is a cutie  I will try to get some added in the next few days. Your guy sounds like a cutie. Roaned sides? Sounds interesting!


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## APHAforlife (Mar 2, 2011)

NdAppy said:


> APHA - you said she has tested homozygous for black and tobiano. Did you have her tested for agouti (bay) as well? Her pictures in your "barn" are making my suspect the possibility of brown.


I have not...when we bought her she already had the test papers they just came long with her...now I am curious haha. I would have to check, but I know that somewhere on them it says something about she will pass black and bay based horses but no reds. Is that what you mean? They possibly checked for both *pulls out binder* I will have to double check. If that is the case, does it change the genetic possibilities as far as color again goes for the foal?


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## NdAppy (Apr 8, 2009)

It does change them slightly if you know.


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## CheyAut (Nov 26, 2008)

sunedee said:


> How are the different agoutis inherited? My youngest is a wild bay. Dam is flaxen sorrel and sire is a bay dun. I think his sire must be homozygous for some sort of agouti because all of his foals are either black, bay, grulla or dun. Or will agouti on black give you a bay I guess? I'm confused ... lol.


Can't be homozygous agouti if he sired blacks and grullas. Agouti would turn them into bays and bay duns.


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## APHAforlife (Mar 2, 2011)

Okay, so I've narrowed it down and have a possible breeding to Mr Zippo Pine this Spring. He is a chestnut 15.2hh stallion ... with my 14.3hh black homozygous mare ... would that lead to the same possibilities that were given on here previously?


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## Poseidon (Oct 1, 2010)

I don't know the genetics of Mr Zippo Pine (as in, if he carries Agouti or Silver or not), but if your mare is homozygous for tobiano and black, you're looking at 50% black tobiano and 50% bay tobiano.


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## APHAforlife (Mar 2, 2011)

Poseidon said:


> I don't know the genetics of Mr Zippo Pine (as in, if he carries Agouti or Silver or not), but if your mare is homozygous for tobiano and black, you're looking at 50% black tobiano and 50% bay tobiano.



Hmm...something to think about. Thanks!


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