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Discussion on Bay Mare in foal to Buckskin/Tobiano/Homozygous Stallion - guesses on color?
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Member:
Kathoien
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Posted on Monday, Jul 21, 2003 - 4:20 pm:
When setting up this breeding, my husband and I were hopeful on getting a black and white pinto. What are our chances of actually getting that? The stallion is a registered paint: APHA #561,263 - carrying the red gene ??
Our mare is a registered Bay Arabian Mare.
My husband and I are registered with more questions than answers !!
 Thanks for your time ...
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Member:
Heidih
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Posted on Tuesday, Jul 22, 2003 - 12:27 pm:
Your chances of getting a black and white foal are very small. If the stallion is homozygous for tobiano, you will definitely get a tobiano. However, as to body color, your mare carries at least one copy of the black gene, however it is modified by agouti (bay) which limits the black to the points. The stallion also carries at least one copy of the black gene and at least one copy of the agouti gene. He also carries one copy of the cream gene. As to whether or not you could get a black depends on whether either parent is homozygous for the agouti gene and for the black gene. If you know the colors of each of the parents (stallion and mare) it will help determine the potential colors of the foal.
My best guess is that you have about a 50/50 chance of a bay or a buckskin tobiano foal.
Now if both parents are heterozygous for agouti, you have a 75% chance of black points and 25% chance of solid black.
If both parents are heterozygous for the black gene, you have a 75% chance of a black based horse (bay, black or buckskin) and 25% chance of a red based horse (chestnut or palomino).
You'd have to do the math to figure out the exact percentages to get a solid black. Again, knowing the foal's grandparent's colors would help figure the % chances. If any of the grandparents are gray, then knowing their parent's colors will help also.
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Member:
Chrism
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Posted on Tuesday, Jul 22, 2003 - 12:30 pm:
Hmm, is the question, what is the likelihood the foal is black, pinto or otherwise?
And, are you saying the stallion is homozygous for black?
In that case, what do you know about the mare - what color were her parents, has she had any offspring and what color were they? The more you know about her genetic makeup, the more we can predict the foal's color.
There are 2 alleles from your mare that will affect color in your foal - one is for baying - this is the one that makes bay points instead of solid black. It is dominant, so you only need one. If you mare has a recessive non-baying allele, then that could be contributed, which would allow black to be expressed with this stallion as he contributes the non-baying allele all the time since he is homozygous black. If your mare doesn't have a non-baying gene, her offspring with a homozygous black stallion will always be bay.
The other allele that may be passed to the foal is the recessive red one. Your mare could have that. If either of your mare's parents was a chestnut, then she does. But if neither was, it doesn't mean she doesn't have the recessive red! In this case, it doesn't affect the foal's color since the stallion is homozygous black - you need two red genes to get a chestnut, one from each parent. So, you will always get a black or bay foal.
So, I worked my matrix of possiblities of what we know and you have a 1 in 4 chance the foal will be black and a 3 in 4 chance it will be bay.
If you know the mare has produced a black, it is 50/50.
BTW, in the words of Mark Rashid, "A Good Horse is Never a Bad Color."
Cheers.
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Member:
Chrism
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Posted on Tuesday, Jul 22, 2003 - 12:51 pm:
Here is a good site on coat color genetics:
https://www.vgl.ucdavis.edu/~lvmillon/coatcolor/coatclr3.html#genee
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Member:
Kathoien
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Posted on Tuesday, Jul 22, 2003 - 12:57 pm:
Thank you for the input. I will do some research and see if I can come up with the colors of the parents of both horses and respond with that information ...
To answer your question (Christine) about the stallion being homozygous for which gene: tobiano
 Thanks, again!
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Member:
Kathoien
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Posted on Tuesday, Jul 22, 2003 - 2:32 pm:
o.k. I have the parental information:
Bay Arab (Krystle):
sire color: BAY
sire's sire color: GREY
sire's dam color: GREY
dam's color: CHESTNUT
dam's sire color: CHESTNUT
dam's dam color: CHESTNUT
Paint Stallion (Magic):
sire's color: BLACK TOBIANO
sire's sire color: BLACK TOBIANO
sire's dam color/breed: BLACK QH
dam's color: PALOMINO TOBIANO
dam's sire color: BAY TOBIANO
dam's dam color: ROAN OVERO
Will this give me more information? Hopefully, yes ...
I can go back two more generations for color on both of these horses. Pictures of the horses can be found on my profile page ...
Thanks, again!!
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Member:
Heidih
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Posted on Tuesday, Jul 22, 2003 - 4:28 pm:
OK Here goes...
I hope I calculated this correctly. I'm working on the fact that the stallion cannot be homozygous for black, nor can he be homozygous for the agouti (bay) allele, since his mother was palomino, she carried no black gene and since his sire was black he carried no agouti allele. From the information given, I can't tell how many agouti alleles the mare carries, but I know she only carries 1 black allele (mother was chestnut).
If the mare carries 1 agouti allele, this is what I calculate the color percentages to be (keep in mind this is only the base color, the foal will have the tobiano color on top). (I hope I did the math right)
28.1% Bay
28.1% Buckskin
12.5% Chestnut
12.5% Palomino
9.4% Black
9.4% Smokey Black (Black with a Creme gene)
If the mare is homozygous for agouti (has 2 copies) these should be the percentages. There would be no chance for a black if the mare is homozygous for the agouti allele.
37.5% Bay
37.5% Buckskin
12.5% Chestnut
12.5% Palomino
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Member:
Chrism
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Posted on Tuesday, Jul 22, 2003 - 7:05 pm:
Let me try again with the new information. Remember, each parent contributes half of its genetic code to an offspring.
ee means a horse is chestnut as it got the recessive, no black hair e from both parents. Ee or eE or EE means the horse has black hair E from one or both parents. If the horse has aa and at least one E, then the black hair is everywhere. If it is Aa, aA or AA with at least one E, the black hair is expressed as a bay.
In this case, we don't know if the mare's parents give Aa, aA or AA to the bay mare. We do know, since she is bay, that she has at least one A.
I think the stallion is aa Ee. He is solid black, so must be aa (no baying). He had an ee dam, so must be Ee (black hairs expressed, recessive chestnut).
So, I create a 4x4 matrix of possible pairings: Stallion can contribute aE, ae, aE and ae from aaEe. This goes across the top.
Down the side goes the mare's EeA? possible contributions. They are: EA, eA, E?, e? The question mark is either A or a. We'll get to that later.
Each 4 letter combination is what the foal may receive from these two parents. My matrix looks like:
Sire >....aE......ae......aE......ae
Dam
'
EA......aEEA....aeEA....aEEA....aeEA
eA......aEeA....aeeA....aEeA....aeeA
E?......aEE?....aeE?....aEE?....aeE?
e?......aEe?....aee?....aEe?....aee?
If you count up the number of entries that have only ee (chestnut), that is 4 out of 16. So, the probablility of a chestnut is 25%.
If you count up the number of entries (ignore the ones with a question mark) with one or two Es, you get 6 out of 16. Put this aside a minute.
Now look at the entries with a ?. That ? is either an A or an a. (50/50 with what we know). So, exclude the ee ones with a ? (they've been tallied)and count up the remainder that have one or two E and a ?. That number is 6. Since there is a 50/50 chance for the A and a, half of those can be a and the other half can be A. So, add 3 more 16s to the 6 we already have for bay and we get 9 chances out of 16 we get a bay or 56+%
So, that leaves 3 chances out of 16 that we get a black. 18+%
Since neither parent is expressing a dilute, I'm not sure that is a factor here.
I could be all wet. But I like the matrix approach to sorting it out. I had to put the dots in to keep the spacing from messing up.
Have fun!
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Member:
Heidih
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Posted on Tuesday, Jul 22, 2003 - 9:45 pm:
Chris, your numbers and mine look to be about the same except that I am factoring in the fact that the stallion is a Buckskin and therefore is expressing the dilute gene, so my numbers are 1/2 of yours putting in that 50/50 chance of dilution.
Kathleen, between the 2 of us I hope we helped you.
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Member:
Chrism
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Posted on Wednesday, Jul 23, 2003 - 11:03 am:
Oh, big duh. I was sure the sire was a black tobiano to start with!
My main point was trying to show how you could work through this stuff using a matrix of possiblities. It is easier to do than describe, GRIN.
Cheers all. Let us know what color the baby turns out to be!
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Member:
Kathoien
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Posted on Wednesday, Jul 23, 2003 - 3:17 pm:
Thank you, so much for all the help! I will definitely let you both know what color we end up with ... can't wait ...
Thanks, again - Kathleen
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