While on the topic of pinto patterns....

[Becky]

Specifically, there is a gene or genes or a modifier that limits pinto markings? Are there any new thoughts on this or any tests in the works? It would be nice to know prior to breeding what horses are going to reduce white and which ones are going to turn it on. Especially in tobiano.

 

[Songcatcher]

It is widely speculated that there are genes that restrict the amount of white in Pinto patterns. I think the fact that certain lines of horses have abnormally high numbers of minimally marked horses attest to that fact. However, that gene has not yet been identified.

There are those who contend that Black is a restrictor. I suppose that is based on the fact that there seems to be more minimally marked Black Pintos than there are Sorrel/Chestnut Pintos. Still, there are numerous wildly marked Black Pintos and some minimally marked Sorrels. So that doesn't fully answer it for me.

 

[Charlotte]

Hmmm, Freeland, I hadn't heard of the thought that black (I'm assuming that would be 'black based'?) might be associated with restriction. Hmmm, I need to go back through my years of foaling records and see what I come up with.

 

[ohmt]

Going through our foaling book, it seems as though our bays are the ones that are usually minimal. We used to have a bay minimal tobiano stallion with a tiny snip and bred to solid and minimal pinto mares he often produced 50/50 or more pinto foals. For us at least, it looks like most of those "loud" foals were either chestnut pinto or black pinto. Most of the minimals were bay. So I wonder if agouti might effect it at all? I will have to take a look at some other crosses and see what I come up with-I have my great grandparents foaling records too so I have pinto based breeding records from 1980 and on

Looking at the foal records for a black homozygous pinto stallion we used to own (50/50 marked, sired by stallion mentioned earlier and out of a minimal black pinto mare), he produced pretty evenly the amount of "loud" pintos and minimal out of almost all solid mares (mostly chestnut). But, all of the foals were either chestnut or black, no bay.

A bay homozygous pinto and homozygous agouti mare we used to own (minimal pinto, sired by stallion mentioned earlier and out of a bay minimal pinto mare) produced nothing but very minimal foals. Her foals were either bay, buckskin, or chestnut, and none of them had anything more than stockings and a little bit of white on their rump.

So now I am getting really curious! Will do more research and let you know what I find. I think I can post pictures of most as well if anyone is interested.

 

[Joanne]

I would think that that restricting gene might be harder to find, due to the variations that can occur.

We seem to have both side of the spectrum here.

There are minimal pintos, such as Rowdy, that produced some incredible loud foals. And other lines that were loud that did not reproduce themselves.

You can see why the breeders that find that special "Nick" stay with their findings.

 

[targetsmom]

How do you define "minimal"? Rowdy is clearly minimal pinto, no matter how you define it, but as someone trying to raise minis that can be registered with the Pinto Association the definition is a bit different. I think it is 2 sq inches of white for a mini, not counting leg or face white unless the face white extends behind a line drawn from the mouth to the ear (please don't quote me on these as they are approximate but I hope you get the idea). But minimal to someone else might be something very different. We don't really care if a mini is LOUD or even if they turn gray, as long as PtHA will accept them in the color registry. So many of our minis are what someone else might call "minimal".

 

[Becky]

Interesting thoughts on the subject. I never thought of pattern restriction as possibly being color related. Now, that is very interesting!

 

[Lewella]

There was a study a decade or more ago in Arabians where the level of white markings was compared on chestnuts vs bays and blacks. They did determine that in Arabians white markings tend to be bigger on the chestnut horses than they are on the bay and black horses. Arabs are pretty limited as to their white marking genetics though so there wasn't a lot to interfer with the expression level.

Base color doesn't appear to effect Tobiano or Sb1 expression levels at all. As Freeland noted though there are definitely some lines that are prone to minimal expression, particularly minimal expression of Tobiano.

I don't ever use what PtHA qualifies as pinto in determining what is really pinto. For example - a maximum white will be registered by PtHA as breeding stock even though it is in reality one giant pinto spot.

 

[REO]

The two bay pintos that Nort sired are mostly white. I know of other bay pintos that are also mostly white too.

A pattern related opinion:

I still think there are more than 3 types of Splash

 

[wcr]

Being a paint breeder for many years, it has often been said that bay is a hard color to break. Meaning solid bay bred to pinto was hard to get pinto on resulting foal.

 

[mini horse mania]

Being a paint breeder for many years, it has often been said that bay is a hard color to break. Meaning solid bay bred to pinto was hard to get pinto on resulting foal.

I will.agree to that...especially on our apha horses in the past

 

[Charlotte]

How do you define "minimal"?

I just posted something about this on the post announceing of our first foal of 2012.

I don't think I've ever seen a written 'definition' of minimal tobiano. I suppose at this time it is just left up to individual interpretation.

 

[Lewella]

Being a paint breeder for many years, it has often been said that bay is a hard color to break. Meaning solid bay bred to pinto was hard to get pinto on resulting foal.

A bay is simply a black horse with an Agouti gene.

I think what everyone tends to forget is that every single conception has a 50% chance of inheriting a gene from a given parent (unless that parent happens to be homozygous - then there is a 100% chance). Sometimes you are just going to have bad luck and they are going to pass that gene much less than 50% of the time. I have a mare that is an excellent example of this. She is an Ee black tobiano. Her tobiano is linked to her black gene so when she passes black, she passes tobiano. Her tobiano production record is absolutely dismal!

Bred to an Ee blue roan going gray - solid chestnut filly

Bred to an EE black homozygous tobiano - black tobiano colt that was not tested to determine if he is homozygous

Bred to a Chestnut Sb1 Sabino - chestnut colt

Bred to a Chestnut Sb1 Sabino - chestnut colt

Bred to a Chestnut Sb1 Sabino - chestnut Sb1 Sabino filly

Bred to a dark seal brown - dark seal brown filly

That is a 16.66% tobiano production record and since the one tobiano colt was never tested to determine if he is homozygous or not her tobiano produciton record could in reality be 0%. Talk about losing the genetic lottery! And it had nothing to do with what color she's been bred to or anything like that - it is just sheer bad luck that every conception was an egg that didn't have a tobiano gene!

 

[targetsmom]

My big horse Target was a bay pinto and about as wild color tobiano as you can get - 50/50 and very well marked. He may have been HZ but was never tested. He was unregistered so no idea of pedigree.

 

[Charlotte]

so Lewella, those 'solid' foals from the tobiano mare have no white ANYWHERE???? Wow.

 

[Lewella]

They all have no tobiano white - the reds can't as her tobiano is black linked at Extension and the seal brown filly inherited her red and not her black linked tobiano. The red inheritors all have some "normal" non-Sb1 sabino markings with the exception of the chestnut filly who has only a few white hairs on her forehead. Maybe this year she'll finally concieve with an egg that has Tobiano but after so many non-tobiano foals I'm not holding my breath!

 

[ohmt]

Ok, I am not very well versed when it comes to pattern genetics so bear with me.

Tobiano is color linked?

I am just thinking of a black pinto mare I have that is heterozygous black and bred to a solid chestnut stallion (all kahoka bred) she has produced both chestnut pinto and black pinto alike. Same with her black pinto brother that is also heterozygous black. Is it only sometimes linked? I am just going back to my genetics education and curious as to how it could only be sometimes linked.

 

[ohmt]

Scratch that question, I looked it up and found the answer for myself

 

[Songcatcher]

Scratch that question, I looked it up and found the answer for myself

Well, share that answer with the rest of us. I'm certainly drawing a blank on it.

 

[ohmt]

This isn't the best one I found, but it does explain the basics pretty well: http://www.apha.com/breed/geneticeq2.html

On the article I read, it also explains that there is about a 7% crossover rate, which would explain why my heterozygous tobiano and black horses have produced pintos of both base colors when bred to solid chestnut horses (horses are true solid chestnut-absolutely no pinto genes and are not silver bay).

The black pinto mare's produce record:

Bred to solid chestnut: Chestnut pinto filly

Bred to solid chestnut: Black pinto colt

Bred to Bay few spot appy: Bay Sabino Blanketed Colt

Bred to Bay few spot appy: Black leopard appaloosa colt

Going by what I have read, the mare's tobiano is most likely linked to Extension-red and the black pinto colt that she produced was due to crossover. Since the bay few spot appaloosa she was bred to is homozygous black, I am betting that if I tested her 2 colts, I would find that they are homozygous black as well, receiving a black gene from their dam.

The black pinto stallion's produce record:

Bred to chestnut tobiano+splash+sabino: Chestnut tobiano+splash+sabino filly

Bred to solid chestnut: Bay Pinto Filly

Bred to bay tobiano +splash: Solid bay colt with blue eyes and offset strip and snip (splash)

Bred to solid chestnut: Solid Bay filly

Bred to solid Red Dun: Solid Grulla filly

Bred to solid Red Dun: Silver Black Pinto filly

So the stallion's tobiano gene is probably linked to Extension-red as well and his bay pinto and silver black pinto filly are the result of crossover. Seems like I have a much higher rate of crossover with my horses, though this is a very small sample and could be attributed to chance.

Bay Pinto Mare-heterozygous black, agouti, and tobiano

Produce Record:

Bred to Solid Chestnut: Solid Chestnut filly

Bred to Bay Pinto (Same genetics as mare): Chestnut Tobiano colt

Bred to Bay Pinto (Same): Bay homozygous Tobiano (het black) filly

Bred to Bay Pinto (same): Black Pinto filly

Bred to Solid Chestnut: Bay Pinto filly

Bred to Bay (homoz tobiano, het black and agouti): Bay homozygous Tobiano filly

Bred to Bay Pinto (same): Solid Black colt

After going over the Bay het Pinto stallion's produce record, I am fairly certain his tobiano was linked to Extension-red. So this mare's tobiano is very likely linked to black and the bay pinto filly sired by the solid chestnut is probably due to crossover.

Lewella: Am I on the right track here?