Would you genetics experts mind commenting on this quote?

[vineyridge]

Because the WB mare already stands uphill and in a sporthorse frame. When you bred her to a TB stallion , she changes very little. You inject more blood in the phenotype and genotype of your WB stamm this way. The goal is to get a TB / WB filly and then cointinue to breed that TB / WB filly over generations.

When you are trying to breed sporthorses from TB mothers it is very difficult because she does not stand in a sporthorse frame. She stands in a racing frame that must be changed and I personally have witnessed SOME who still had the undesireable race horse traits 5 generations later.

Most crosses from TB mothers are incapable of competing at the top of the sport unless they have been bred over several generations and even then they are rare in the top showrings.

Frame to this guy means skeletal frame or conformation, not "frame" that comes from training.

Is he correct that the stallion has far less influence on the foal than the mare, and that TB mares are simply unusable in top level jumpers and dressage horses?

He breeds Holsteiners in Holstein from only mares who come from Pure Holstein mare lines.

[kimberley mine]

I call bullshit.

First, there is automatically a selection of type with thoroughbred stallions approved to warmblood mares. No judge worth her salt is going to approve a stallion who looks like Speightstown (bless his little butt-high heart) for a warmblood registry--she will pick a horse who is more compatible with the warmblood type. Nor will she pick a horse who is built like, say, Leroidesanimaux. A horse like, say, Galileo is FAR more likely to be approved.

If for some bizarre reason a stallion like Speightstown is approved, then unless all the mares he is bred to are ridiculously prepotent themselves, some of them will have the butt-high, heavy frame, and will be highly likely to pass that trait on to further generations. For that matter, unless the mares themselves are highly prepotent, some of them will have the "racehorse frame" in their offspring, or have it pop up at odd times.

As far as proof that a full-blooded thoroughbred can't compete at the highest levels in international jumping, I offer Coconut Grove right off the top of my head, followed by Hand In Glove, Heraldik, and Stravinsky (POL).

Moving on to thoroughbred mares being more likely to pass on "racetrack frame" than thoroughbred stallions, particularly inbred and thus likely to have more uniform genetics to hand down thoroughbred stallions....I just can't see any logic behind that statement. I also wonder where, exactly, the guy thinks thoroughbred stallions come from...if you have a thoroughbred stallion with superior sporthorse conformation and superior jumping ability...doesn't he have a dam? Who is likely to have superior sporthorse conformation and ability?

[Pan Zareta]

I call bullshit.

Ditto that!

A mare contributes slightly more nuclear DNA than the sire to their sons simply b/c the X chrom. has a lot more genes on it than the Y chrom. But that only applies to males, and the vast majority of nuclear DNA is on the autosomes (50% from each parent). This guy's apparent conclusions remind me of some of the crap the foundation QH people come up w/ re. the TB.

[xfactor fan]

I've been seriously looking at inheritance of conformation for the last several years, and taking out the breed bias, I can see where the statement comes from.

Here's another question that may be related:

Has anyone studied harem species to see if there is an un equal gene flow from the two sexes? Do more paternal genes get turned off in horses than in monkeys?

[vineyridge]

He's now basing his conclusions on epigenetics, claiming that the immediate tail female is the most important because of that. He says F1 TB on top x WB mares are only good for anything after their descendants have been bred back to WB stallions for generations. And that TB mares are just incapable of producing top quality for sport.

I've said over and over again that the German attitude is based mainly on their experience, where the number of TBs is so low that good TB mares simply wouldn't make it into the WB breeding pool. I know the Swedes are much less biased against blood on the bottom, and even some of the Dutch have been successful in the past using TB mares. The French certainly have had much less bias against blood on the bottom in the past, but they have a far larger TB population than the other continental Europeans.

If he were correct, then in racing TBs the tail female line would be the single most important factor in breeding. And don't we know that is not the generally accepted view in TB breeding?

BTW, Cornell currently is doing genetic research on the genetic bases of conformation.

[kimberley mine]

I've said over and over again that the German attitude is based mainly on their experience, where the number of TBs is so low that good TB mares simply wouldn't make it into the WB breeding pool.

See my earlier comment about selecting for type. Good thoroughbred stallions with outstanding sport performance and type are likely to be bred to a wide variety of sporthorse mares (again, Coconut Grove). Good thoroughbred mares with outstanding sport performance and type will probably be bred to....thoroughbreds. Especially in countries with a lively National Hunt scene.

I know the Swedes are much less biased against blood on the bottom, and even some of the Dutch have been successful in the past using TB mares. The French certainly have had much less bias against blood on the bottom in the past, but they have a far larger TB population than the other continental Europeans.

The entire French idea in breeding the Selle Francais, so far as I understand it, is to have a thoroughbred with thicker bone...not a lightened up harness horse. Also, I submit that the very existence of the French Anglo-Arab is evidence that the French were more willing to use hot blood horses to create superb sport and riding stock.

[xfactor fan]

Do you know who at Cornell is doing the research?

What I'm seeing is that forehand and hind end conformation are passed on independently.

Just for fun, take a look at Northern Dancer's hind quarters, then look as the hind end of as many ND sons as you can find. Front ends don't look like ND but the hind ends do.

[vineyridge]

Here's a quote from a post on the Chronicle Forums:

the Sutter Genetics Lab at Cornell is working on a study of inheritance of size and frame. There was a thread last year that asked for volunteers to measure their horses and send in DNA samples. I participated and asked for more info about their research. They're working on the DNA sequencing and identification of genes that control body shape, not epigenetics. But it is certainly a first step to future studies of gene activation. Epigenetics would absolutely explain a tendency for frame to come from the motherline. It also explains why draft, warmblood and thoroughbred surrogate mares produce different types of foals in embryo transfers.