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Is winning the Kentucky Derby relevant to the breeding industry?

We have just witnessed the 140th running of the Kentucky Derby. No doubt by now that there will be stud farms around America now jockeying for positions to take a chance at stud with the brilliant California Chrome.

A rational precis of California Chrome's pedigree would be as follows - his sire was well bred, talented, but suffered from a breathing problem which compromised his career. His dam was a modestly performed runner, by a well-bred and well performed regional sire, who was out of a modestly performed mare. In summation, he's Mendel at his best, the genetic 10,000-1 shot that you would go broke trying to do again (unless it is that mare and that sire). We've seen these types of horses in the past, the freak athlete that then goes on to a successful stud career like Candy Ride, Tiznow and Indian Charlie, but for each of those stallions we can recall at least another ten that failed.

Regardless of what he does next, one of the 'selling points' for the horse is that he won the Kentucky Derby. The great Italian breeder and trainer Frederico Tesio once said...."The Thoroughbred exists not because its selection has depended experts, technicians or zoologists but one piece of wood: the winning post of the Epsom Derby." He was suggesting by saying this that the breed's improvement is based on the winner of the Epsom Derby and that an Epsom Derby winner is what we should be trying to breed. Just like the Epsom Derby in England, there is a fascination with the American breeding industry about both breeding the Kentucky Derby winner and standing Kentucky Derby winners at stud. The question is, is that goal justified?

If you presume that a single race can be classified as "sire making", a fair assumption to be making itself, if anything, the data suggests that Kentucky Derby has been the race not to win if you want to be a leading sire. From 1975 through to 2009 there has been 37 winners of the Kentucky Derby. If we take out the fillies, Genuine Risk and Winning Colors, the ill-fated colts in Swale and Barbaro and the geldings Funny Cide and Mine That Bird, we are left with 31 colts that have won the race and gone to stud in that period with data we can use.

Now obviously a Kentucky Derby winner generally gets a good start at stud, certainly better than an average stallion so you'd like to think that these stallions did well in their new careers. While the Graded stakes system tends to vary a little over years depending on the population, it is a decent barometer for measuring overall stallion success with the most successful stallions generally siring 30+ Graded stakes winners in their lifetime, an average stallion between 15-30 and a below average sire from 0 to 15. Here is the list of the Kentucky Derby winners since 1973.

Note: Thunder Gulch, Real Quiet, Fusaichi Pegasus and Street Sense have all shuttled. The numbers above are only GSW from their North American crops.

Even accounting for the sub-fertile War Emblem, from that list you could only have Seattle Slew, Affirmed, Pleasant Colony and Sunday Silence as good stallions although you could add Unbridled, who died young and would have easily passed that number. That is 6 from 31 and you'd say, with due consideration to Street Sense who projects as an "average" stallion with 15+ lifetime GSW in a full career, that 16 of the 31 had or are going to have careers that will be described as "below average". For stallions that have had a better than average start that is awful.

So we can discount the belief that the Kentucky Derby as a sire making race but here is where it gets a little more interesting. One of the more accurate (actually probably the most accurate) handicapping figure in North American racing are the Ragozin numbers. They take into consideration a number of factors and are a very good measure of what the performance of a horse was in a given race. If you want more information about how they work you can click here

The first thing to consider is that there is an extraordinarily weak (r=0.19) correlation coefficient between the Ragozin number that a Kentucky Derby winner runs in that race and the number of graded stakes winners that he subsequently sires. It is bordering on a negative relationship (i.e stallions with slower Kentucky Derby figs are better sires). Here is a linear regression plot of the data.

Not only is the race in general a poor guide as to his chances at stud, how fast he runs in that race, has little correlation to his ability to sire graded stakes winners and his overall merit at stud. The fastest 10 colts by Ragozin number (Big Brown at -0.75 to Silver Charm at a 3) have sired an average of 11.2 graded stakes winners lifetime, while the slowest ten by Ragozin figures (From Pleasant Colony at 5.75 to Cannonade at an 8) have averaged 17.5 graded stakes winners. While California Chrome may go on to have a fantastic race career his win in the Kentucky Derby and how fast he ran in it, will have little relationship to his performance at stud.

POSTSCRIPT: Joe Applebaum, a noted pinhooker and thoroughbred investor asked me to take a look at the relationship between the Ragozin figure run by the Kentucky Derby winner and their subsequent lifetime stakes winners to foals percentage. I don't particularly like using open stakes winners to judge merit as there is little difference between a Listed winner in one place and a solid allowance/handicap winner in another, but here it is.

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