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

I have an APHA mare that is tested homozygous for both her color (black and white) and her pattern (tobiano). If she was bred with a homozygous dun or red stallion, how exactly would that play out for the color/pattern of the foal? I am not too familiar with genetics and have been fairly curious. I am not breeding her as obviously I am not experienced, but I would love any information that you might be able to provide :) Thanks and God Bless.

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

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 aa, Aa, AATT eennnnnnnnnnDdrrnngg
Dam Color: Black Tobiano aaTT Ee, EEnnnnnnnnnnddrrnngg

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

Grullo Tobiano Black Tobiano Bay Tobiano Bay Dun Tobiano Red Dun Tobiano Chestnut Tobiano


















Time = 0.109375 sec

Offspring Color Probability

Grullo Tobiano Grullo Black Tobiano Black Bay Tobiano Bay Dun Tobiano Bay Dun Bay Red Dun Tobiano Red Dun Chestnut Tobiano Chestnut

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

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

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

^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!!

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!

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 ... :(

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