Updated 7/1/07

Ask Prism your color genetic questions!

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The Horse Gazette
6395 Mondean Street - San Antonio, TX 78240
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Bay Mare to Palomino Stud
(Added 7/1/07)

Hello Prism,
I have a grey mare that was out of a bay mare by a grey stallion. When Mira was born she was a bay. I am thinking of breeding her to my friend's Palomino stud. What do you think my foal would be? Thanks! Sarah Barkley

Dear Sarah,
Knowing her base color is Bay (born bay) we can say that the foal could be Sorrel, Palomino, Black, Bay or Buckskin. If by some chance the mare was homozygous for black then you can rule out the Sorrel and Palomino. - Prism

Sorrel Mare to Buckskin Stud
(Added 7/1/07)

Dear Prism,
If I breed a sorrel mare to a buckskin stallion what color foal do you think that I will get? Will I get sorrel, bay, or buckskin? Thanks, Meghan

Dear Meghan,
Breeding a Sorrel to Buckskin (bay plus one dilute gene) could give you a Sorrel, Palomino, Bay, Buckskin or black. - Prism

Brown Mare to Dun Stud
(Added 7/1/07)

Dear Prism,
I bred my brown mare to a dun stallion. What colour will the foal be? Thanks, Ryanne

Dear Rayanne,
The answer depends on the base color of the stallion. Brown is black, which has been modified; by a form of Agouti (shown as At) and the Dun could be a Red Dun, Classic Dun or Bay Dun. Without knowing more information on the exact color of Dun that the stallion is the foal could be a Sorrel, Red Dun, Bay, Bay Dun, Black or a Grullo. – Prism

Occurrence of the Gray Gene Rests Solely with the Horse that is Gray
(Added 7/1/07)

Dear Prism,
I have a gray Dutch mare (red base) her dam was grey, her sire bay she has three full brothers all bay (in fact out of several gray mares mine is the only gray offspring the sire has ever thrown of all 20 or so breedings to various gray mares all others have been bay). I'm unaware of her maternal grandparents colors her paternal ancestors are bay all the way back to forever. I know there is theoretically a 50% chance she will pass on the gray but would it slant the odds in my favor at all to breed her to a bay that like her sire comes from a long line of bays (to avoid the graying gene). Thanks, Kelly Borchers

Dear Kelly,
Unfortunately not. The occurrence of the gray gene rests solely with the horse that is gray. In this case, your mare. Every time you breed her (or any gray horse which is heterozygous for gray) there is a 50/50 chance that they will pass along one of the two genes, which reside at the allele for ‘gray’. It is possible to breed a gray stallion 100 times and not have a gray foal until foal number 50…but one can’t beat mathematical odds. In this case the stallion will not influence the occurrence of gray, as he does not carry a gray gene. Remember each horse carries 64 chromosomes and they get 32 from each of their parents. It is this ‘pairing up’ of chromosomes which gives us all the variations in color, conformation, disposition, etc. and why full siblings can be so very different from each other. – Prism

Test Filly to Determine if She Carries Two Tobiano Genes
(Added 7/1/07)

Dear Prism,
I have a black and white (tobiano) filly. Her sire is black and white (heterozygous) and her dam is a solid bay (by a paint sire). Is it possible for the filly to be homozygous for the tobiano gene? – Linda Bird

Dear Linda,
Your filly could only be homozygous for the Tobiano gene if both parents were Tobiano and each one passed a Tobiano gene to the filly. We know she got one Tobiano gene from her sire. If her dam is by a Tobiano and does not have any white markings, I’d venture a guess that she did not inherit the genetics for the Tobiano pattern and doesn’t carry it in any form so she will never pass a Tobiano gene to offspring. If you absolutely want to know I would recommend having your filly tested to determine if she carries one or two Tobiano genes. - Prism

Dbl. Homozygous Paint to Gray
(Added 6/1/07)

Dear Prism,
I have a double homozygous black & white paint mare that I’m breeding to a non-homozygous gray stallion, Will the black & white Double homozygous mare breed true to black or does the offspring have a 50% chance of still going gray do to the non-homozygous gray stallion. I understand if the gray stallion was homozygous for gray it would dominate the black homozygous gene. Help and thanks, Jim

Jim,
With your mare being homozygous for black she will always produce a black-based foal, but depending on the Agouti (Bay gene) status of the stallion you could get a bay out of the mix. Gray is known as the “Ultimate modifier” in that regardless of the birth or base color of a horse if it carries one gray gene the color will change to gray. So this cross will produce a black-based foal with a 50% chance of being gray. The mare will give a black gene (and I am making an assumption she is Tobiano) and a Tobiano gene. Being homozygous for those two genes makes it a given. The stallion has a 50/50 chance of passing the gray gene to the foal. - Prism

Palomino to Black
(Added 6/1/07)

Dear Prism,
I have a Palomino walking horse out of the Generator genes. Lots and lots of gold in his background. I am going to breading him to a Black mare directly out of the pusher. She has lots of black in her back ground. I am also going to bread him to a red roan mare and some black and white spotted tobiano mare. They are all walking horses as well. Is there any chance of getting any buckskin colts and out of the red roan and spotted mares a lemon drop colt? Thanks, Justin

Dear Justin,
Palomino is a red-based horse (Sorrel/Chestnut) with 1 dilute gene – or homozygous for red and heterozygous for Dilute. Breeding him to a black mare could result is Sorrel, Palomino (if the black mare is heterozygous for black), Black or Bay. (Depending on the Palomino’s Agouti gene status). Crossing him on the Red Roan mare could produce a Sorrel, Palomino, Red Roan or Palomino Roan foal. And yes, if the foal inherits 1 black gene, 1 Agouti gene and the dilute gene (from the palomino) you could get a Buckskin foal. I have never heard of a “Lemon Drop” color so I am assuming you are meaning a Palomino and White foal. That is indeed a possibility. - Prism

Palomino to Roan
(Added 6/1/07)

Dear Prism,
My palomino stud bred our roan mare. What color do you think the foal will be? Sherri Pickerell

Dear Sherri,
Only two possibilities in base colors. Red (Sorrel/Chestnut) or Palomino. The other possibilities with this mix would be Red Roan or palomino roan. Both the stallion and mare are red-based and do not have a black gene to contribute to the foal. So you’re stuck with red as your favorite color. - Prism

Will Grulla Foal Turn Grey?
(Added 6/1/07)

Dear Prism,
I have a 10-month-old weanling out of a buckskin turned grey mare and a grulla stallion, the weanling looks grulla, if she’s going to grey do I still have a chance of a grulla foal out of her someday? What would she need to be bred to? Jen

Dear Jen,
At 10 months it is indeed difficult to determine if the foal will turn gray. But even if she does turn gray she will still carry the genetics to produce a Grulla which is Black plus Dun and could easily produce Grullo/Grullas in the future. To maximize the chances of her producing a grullo/grulla I would breed her to either a black-based horse or another Grullo. You don’t want to weaken the chance of a black gene by introducing more Red into the mix. Breeding her back to a Grullo will also heighten the chances of producing a dun. - Prism

What Color to Breed to a Palomino Mare?
(Added 6/1/07)

Dear Prism,
I recently purchased a palomino mare and have so much fallen in love with her beauty and her disposition that my wife and I have decided to breed her in hopes of getting a little one with many of the same characteristics. We would like to breed her with a stallion which will give us the greatest likelihood of a palomino offspring...can you please steer us in the right direction? Greg

Dear Greg,
If you are breeding for the Palomino color your only choices would be to breed to a Palomino or Sorrel/Chestnut. If you breed to a Sorrel/Chestnut you would have a 50% chance of having a Palomino and a 50% chance of having a Sorrel/Chestnut. If you breed her to a Palomino you have the same 50% chance of having a Palomino but you can add in a 25% chance of a Sorrel/Chestnut and a 25% chance of having a Double-dilute (i.e., Cremello). Unfortunately, breeding for disposition is much trickier. There is no way to guarantee that a super dispositioned mare will have a super dispositioned foal. Too many factors play into the mix. Sire’s disposition is 50% of the package and you just need to weigh that as much as conformation and color. And there is still the possibility that the foal’s disposition could be totally different than either parent. - Prism

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