Dosage Figures for Elite Thoroughbreds Since 1983

The table below displays Dosage figures for selected groups of "elite" Thoroughbreds since 1983.  The "elite" horses include winners of the Kentucky Derby, Horse of the Year, Annual Leading Earners, Annual Leading Sires by Progeny Earnings, Annual Leading Broodmare Sires by Progeny Earnings, and Kentucky Broodmares of the Year.  The individual and combined figures are compared to those for open stakes winners over the same time frame.  Abbreviations in the table are ADI for average Dosage Index; ACD   for average Center of Distribution; CDI for Composite Dosage Index; and CCD for Composite Center of Distribution.  Composite figures are derived by adding the points in each aptitude category for all members of the group and then calculating the DI and CD in the normal way.

Several differences between the "elite" horses and typical stakes winners are immediately obvious.   Although there is some variation from group to group, all of the "elite" groups show double digit representation in the Classic aptitudinal category.  The stakes winners do not.  All of the "elite" groups have more total Dosage points than the stakes winners, mainly concentrated in the breeding stock (sires, broodmares, and broodmare sires).  The "elite" runners have fewer Dosage points than the "elite" breeding animals.  The "elite" horses as a group have more representation in the stamina wing of the DP (Solid and Professional aptitudinal categories).  The leading sires possess far more Brilliant and Classic points than do the stakes winners, while the broodmares and broodmare sires are most heavily weighted toward stamina.  The Dosage figures are generally lower for the "elite" horses, again with variation from group to group.  Note that the ADI of the Kentucky Broodmare of the Year group is heavily influenced by one representative with very high numbers.  This is not as obvious in the CDI.  The conclusion one might draw from these data is that the pedigrees of superior Thoroughbreds can be differentiated from the pedigrees of typical Thoroughbred stakes winners by the magnitude and degree to which they have inherited prepotent influences for speed and endurance.