Last week we discussed the fallibility of the Dosage "rule" for the Kentucky Derby. (Derby winners are supposed to have enough stamina influences to rate 4.00 or lower on the Dosage scale.)
I predicted the rule would have to change because today's North American Thoroughbred is being bred for speed (high Dosage Index) and eventually Derby winners -- in fact, pretty much all Derby runners -- will have a much higher average Index.
This past weekend, Mine That Bird (profile) powered home an impressive winner "despite" his 5.40 DI.
If you think I'm going to gloat, uh uh. Not this time. I don't believe that Mine That Bird really deserves such a high DI.
Mine That Bird's Dosage numbers aren't wrong, they're just not right -- yet.
The Dosage Profile of this year's winner of the Kentucky Derby Presented by Yum! Brands (gr. I) is based on two stallions in his third generation (Unbridled and Mr. Prospector) and four in his fourth cross (Fappiano, Northern Dancer twice, and Raise a Native). (Mine That Bird's pedigree.) With the exception of Fappiano, all of these stallions contribute Brilliance to the pedigree. Meaning that on paper -- and using the Chefs-de-Race list as it exists in 2009 -- Mine That Bird comes from a speed-dominant background.
But... Dosage looks only at the influence of specific sires, and of 64 possible Dosage "points" in a horse's pedigree, Mine That Bird has only 16. So far. That is likely to change over time, and his DI will lower because of it.
Give it a few years and we'll see Vice Regent declared an Intermediate sire, and Smart Strike and Storm Bird will be Classic influences. (Vice Regent's current progeny average winning distance is 6.96 furlongs; it's 7.45 for Smart Strike and a remarkably high 8.24 for Storm Bird, making him arguably a Classic/Solid influence but for sake of argument we'll stick with Classic.)
Given those additions to Steven Roman's Chef-de-Race list, we'd find Mine That Bird's DI at 2.76 instead of 5.40. And 2.76 is well under the 4.00 Derby standard. (If any kids are reading today's post, this is why you should study hard at math. So you can come up with some arcane hypothetical calculations about racehorse breeding and impress your fellow pedigree nuts.)
Again, Dosage measures the influence of specific stallions. I doubt that we'll see Birdstone (SRO) or Grindstone (SRO) added to Dosage calculations anytime soon -- but that doesn't diminish their genetic influence, which tends towards stamina. Grindstone's 7.22 furlong progeny average winning distance is indicative and while Birdstone is too young to have a valid progeny AWD, as a runner he himself boasted an 8.96-furlong figure in that category.
So... even if he officially counts as an exception, Mine That Bird shouldn't be used as proof that the Derby Dosage rule is permanently shattered.
(BTW: I'm not forgetting Mine That Bird's other pedigree influences -- including the female lines -- but the focus here is on whether or not Dosage "failed" in the case of this year's Derby winner, and I'm saying I don't think so.)
