Horse running through field

Kentucky Derby Dam Line Index Profiles

by Roger Lyons

The table introduced by this post lists the Dam Line Index (DLI) for the first seven dams of each of the 20 Kentucky Derby 2011 qualifiers. The DLI, remember, is derived from the number of runners winning stakes during the last 15 years and descending, tail-female, from a given dam, divided by the average number of generations that dam was removed in those cases. So, the DLI is, literally, the number of SWs attributable to a dam per generation removed, on average.

The DLI is a pedigree measure and bears only a statistical (read tenuous) relation to performance. What I mean is, you can go very far wrong predicting individual performance based on population characteristics.

There is very little in the DLIs for Uncle Mo’s female line to suggest that he would be Champion Juvenile Colt, let alone a Kentucky Derby winner. What it might suggest, however, is that he is in that respect anomalous to his breeding since, in fact, those accomplishments are largely reserved for horses from better dam lines.

The DLI profiles of Animal Kingdom, Archarcharch, Brilliant Speed, Master of Hounds, Midnight Interlude, Mucho Macho Man, Nehro, Pants on Fire, Shackleford, Soldat, and Stay Thirsty are far more typical of the horses of highest racing class.

Archarcharch has an especially unusual and intriguing profile. Ordinarily, the DLIs in a good female line descend in value from the seventh dam to the first dam, as in the well defined case of Pants on Fire, for example. By contrast, the DLIs in Archarcharch’s female line actually ascend in value from back to front, such that his second dam, Pattern Step (1985), by Nureyev, has a DLI of 5.0, the highest-rated second dam, by far, in the list. This would seem to be the picture of an improving branch of a female line that has otherwise gone more or less dormant.

In any event, see what you can make of the DLI record, but don’t bet on it.

Dixieland Band Delivers

by Roger Lyons

Dixieland Band ranked fifth among broodmare sires on 2010 earnings. Although that says a lot about the quality of his daughters, there’s a lot more to the story of his influence in the ancestries of producers. I can’t tell the whole story because, as anybody who reads this blog already knows, I’m not a horseman in any professional sense.

Sure, I love horses (who doesn’t?) and I’m around them every day, but that doesn’t qualify me to be an authority on exactly what it is Dixieland Band contributes through the dams of horses like Uncle Mo (Indian Charlie-Playa Maya, by Arch), whose second dam is by Dixieland Band. Yes, it’s mildly embarrassing that I’m just a numbers cruncher, but I can live with that as long as it enables me to report that something is happening, even if I can’t say exactly what it is.

So. It happens that Indian Charlie has sired foals out of only nine mares with Dixieland Band in their ancestries through his 2007 crop, and from those nine he got three superior runners, including Two Trail Sioux (G2), also out of a mare whose dam is by Dixieland Band. Uncle Mo (2008) is his fourth.

The bigger story is that Indian Charlie is not alone in having a very high strike rate with mares that have Dixieland Band in their ancestries. A survey of US sires for which I’ve kept comprehensive strike rates over the years turned up 29 that had sired foals out of at least 10 mares that had Dixieland Band in their ancestries, and 11 of those sires had superior-runner strike rates which, like that of Indian Charlie, significantly exceeded their overall records. Put another way, Dixieland Band has a 38% approval rating among contemporary sires.

But that’s not all. Dixieland Band’s disapproval rating is only 7% (55% having average strike rates). To put that in perspective, consider the record of Roberto, sire of Kris S., broodmare sire of Uncle Mo. Roberto has a 23% approval rating, which is still relatively high, but his disapproval rating is 24%. So, basically, if you pick a stallion at random, there’s a 23% chance that he’s going to manage Roberto’s influence quite favorably and a 24% chance that Roberto’s influence is going to be downright unfavorable. You can see by comparison with Roberto, then, that Dixieland Band’s influence through broodmares plays extremely well in the contemporary stallion population, with a very minimal downside risk.

As far as Indian Charlie is concerned, Roberto’s influence is innocuous from a statistical point of view, with a strike rate of 4/40 (Uncle Mo is the fifth superior runner). Yes, there are effects, no doubt, but they don’t pay off all that frequently for Indian Charlie. The numbers say Dixieland Band is probably the major player in the pedigree context of Uncle Mo’s dam, and they also say that Dixieland Band routinely contributes traits that, although quite possibly waning in the stallion population, remain highly exploitable by it.