Bumping this back up. Warning - long post!
Anyone out there have any thoughts on whether the blood% of a distant ancestor in a pedigree has predictive value? I really do want to understand this better.
Here are my thoughts, for what ithey are worth:
To provide some perspective, the blood percentage of each ancestor in the 4th generation (16 horses) is 6.25%; 3.13% in the 5th (32 horses). Base upon what I am seeing from a pretty detailed review of linebreeding reports, even a heavily linebred distant ancestor is unlikely to have a blood % in excess of 6.25% – under this analysis, the blood equivalent of a single 4th generation ancestor.
As I understand it, each sire/dam contributes, on average, about half of the genetic makup of their offspring; in a linebreeding situation, one would expect different contributions of genes to revert to the mean to a large extent. Stallions and mares have to be considered equally. I believe that means that blood % (or perhaps better, AGR) can be used as a rough estimate of the level of influence an ancestor may have on the genes of a horse.
Applying that logic further, I would think that seeking only one “quality” sporthorse ancestor in the 4th generation (each horse at 6.25% influence) of a horse’s pedigree should not get us excited – even if that horse is Hyperion (or, to use a warmblood-breeding reference sire, Ladykiller). In that scenario, ~94% of your F1 horse’s genes likely come from other sources.
Instead, if you are going to breed an animal, you’d want to see that 4th generation literally packed with quality sporthorse ancestors. Every single one should count. At that point it seems to be a mistake to focus on specific sire (or dam) lines in the pedigree; instead, you are hoping that by stacking the deck in more distant generations, you’ll get something of quality in this one.
The complicating factor with Thoroughbreds is that they are not bred for sport, but for racing (duh!). For eventing, ancestor racing success (particularly in turf/NH scenarios), probably does indicate an aptitude for cross country – at least in terms of the overall athleticism, speed and stamina of the animal. For dressage and showjumping a connection between racing success and sport does not seem as clear. My guess is that warmblood breeding, done carefully, is likely to be more predictable for sport than using Thoroughbreds or native-breds, because even 4 generations back you are likely to get a densely-packed set of ancestors evaluated and bred for sport, or with Trakehners, for use in the military. And usually without a closed book.
The exception to this would be where a heritable trait is obviously and consistently being passed down over several generations – color being the most obvious yet least functional of these from a sporthorse perspective, but it could be other observable traits such as conformation and movement. It is easier to track through sire-lines simply because we usually have more information about stallions than mares. If you can show that Bay Ronald-Bayardo-Gainsborough-Hyperion-Owen Tudor-Tudor Minstrel-etc. were all good movers, and the other horses in the pedigree were not known as good movers, then you may have something solid to rely on.
As is probably obvious, I am more concerned about event breeding than anything else, and I am convinced that the thoroughbred will remain a necessary element for event breeding, and will continue to be used from time to time in the more warmblood-dominated sports. Not trying to be a kiss a$$, but this is why commentators like vineyridge and some others here are so important. She’s actually taken the time to understand and really try to find out the sport qualities of what are fundamentally racehorses, and not just the well-known ones. Most don’t have the time or inclination to do that kind of research.
Whew. All of this may be obvious or old news to a lot of people, but writing it down helps me collate my thoughts. :winkgrin:
So, to sum up what I think as to the predictive value of a pedigree based upon what I have reviewed so far:
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An ancestor, even linebred multiple times, is unlikely to overcome the more recent generations of a pedigree unless they have passed down a identifiable dominant trait that has weathered the storm of multiple generations.
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Unless it is in the first couple of generations, the predictive value of a single horse’s appearance in the pedigree is likely to be low.
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Because of this variability, for breeding purposes, the goal should be to have a breeding animal whose distant generations are packed with ancestors who have been identified as being of a “sport type” (in temperment, conformation and/or movement) or who are known to have produced those qualities in the breeding shed. This increases the chances that a sire/dam will also produce a quality sporthorse type.
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Other than looking at obvious conformation traits, it is more difficult to identify thoroughbred “sporthorse” ancestors that predict sport performance than in warmbloods, for example, because of the emphasis on racing success. This is probably less of an issue in eventing than in other discplines, so long as one focuses on racehorses successful at longer distances or over fences.
Add to it; poke holes in it – tell me where I’m wrong or the where the science does not support the conclusions. I post these missives not only to organize my own thoughts, but to solicit those of others as well.
Sorry again for the rant. PF
I don’t get it either, because he was quite a horse apparently! But glad to know you heard the same thing I did… Phew, I feel less idiotic now! :lol:
They’re clearly stamped by him - just sometimes in different wrappers and sizes but that gives into geno/phenotype expression discussion. IMO there are certain characteristics (behavior, rideability, movement) that are color- or sex-linked but that’s just MO…fwiw.