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.