I know homozygous tobianos will produce tobiano ALL the time, but will the offspring of one homozygous tobiano parent and one solid/non-homozygous parent (TB or ISH) have a higher tobiano production rate than say the average 50/50 chance?? Sorry if this sounds confusing. Thanks.
Nope.
50/50 since the solid contibutes negative for Tobiano.
UNLESS the solid is untested and is a minimal Tobiano (not showing enough to determine visually, but geneticallly Toto).
In that case the offspring of that ‘solid’ from a homozygous Tobiano could be Homozygous as well (and would test as Homozygous) and pass on the To gene 100% of the time.
The rest is just the randomness of a coin flip every foal.
Thanks…that is what I thought!!
Retorical question… why is it some non-homozygous tobianos and some dominant white (Puchilingui /TB, offspring particularly) or overos seem to be so much stronger producing color on solid mares?? Our stallion, Puchi’s Rambo by Puchilingui had “almost” 100% color production in his whole breeding career, while breeding only solid mares!! Just asking. Probably just a stroke of luck!!
Sometimes it has to do with color linkage of genes. Bright white was black based, but on the whole the DW families are expressed more on a chestnut base/ repressed more on a black base. I have had 5 white DW foals all on a chestnut base. Now Tobi in warmbloods: you almost always see on a black/ bay base… Hard to find a chestnut tobiano wb.
Interesting concept. Puchi’s Rambo was a chestnut/white, but one of our plain black mares…not a white hair, produced 7 loud overo foals in 7 breedings and every one was dark bay/brown or black!!
I am sure there are a lot of color genetics that haven’t yet been identified or found. But what a surprise it is when you get a colored foal out of a solid mare! And of course, the pattern is always fun, too.
I’ve always likened our foaling to a Christmas Grab Bag!!! I’m ALWAYS pleased and surprised!! We had our first foals by “Challenged” this year. All out of Rambo mares…two overos and a pure white mare. We got three FANTASTIC foals, large, correct, but “spotless”!! Lots of chrome - stockings to knees and hocks, but not one single body spot!! Oh well!!
[QUOTE=camohn;7668643]
Sometimes it has to do with color linkage of genes. Bright white was black based, but on the whole the DW families are expressed more on a chestnut base/ repressed more on a black base. I have had 5 white DW foals all on a chestnut base. Now Tobi in warmbloods: you almost always see on a black/ bay base… Hard to find a chestnut tobiano wb.[/QUOTE]
Interesting. You see this in appaloosas as well. Generally a black based tends to suppress the PATN (which produces the spots etc) while chestnut base shows larger expression.
To build on the gene linkage thing. The Kit gene, which is responsible for the majority of white color patterns shares a chromosome with the base color gene. For the most part the two will divide and transfer together. In other words if you have an Ee Toto horse it will pretty much always split with E/To and e/to. But it does get mixed up occasionally.
So the white on the foals from Puchi’s Rambo and the black mare was from dad’s chestnut/white chromosome, where the chestnut was recessive to mom’s black. Foals of those offspring, (if bred to a chestnut) would most likely be chestnut and white or black/bay and not white. The white is likely still linked to their chestnut gene.
I never bred horses it this reminds me of the white mouse I bred to the black and white mouse (tobiano mouse;)). Two litters - 14 brown mice and 3 orange ones.
Otoh my 2 black foals: 4 socks, one with a star/one not,striped hooves.
