Is Danehill Inbreeding a Pedigree Mistake?

Danehill inbreeding has produced mixed results but is Danehill inbreeding a mistake? For sometime there has been much discussion that Danehill x Danehill would not increase the chances of producing black type horses. The matter appeared to be settled until Guelph (Danehill 2mx3f) won at G1 level. However, may I remind the resurgent believers of the old saying that given a typewriter (computer with Word 2016?), a monkey will eventually produce the entire works of Shakespeare.  I think the excellent work of John Boyce proves that Danehill inbreeding produces less SW than outcrossing..

               Danehill

What does the Data Show?

In the total thoroughbred racehorse population, about 2% will be black type winners. John took the data from 12,640 runners from 26 stallions who had at least 25 or more runners inbred to Danehill.

The percentage of runners achieving black type wins in this overall group was 4.9%. However, among these runners was 1,815 who carried at least one duplication to Danehill. The percentage of SW dropped to 3.2%.  This sample is significant in statistical terms. Inbreeding to Danehill produces less SW than outcrossing.

Danehill yearlings at MM National Sale August 2020

Though inbreeding to Danehill may not be a great choice, it still produces more SW than the average. There are two factors of influence when looking for a yearling inbred to Danehill.

• The 3 x 3 cross has been the most productive. 3f x 3m has produced 25 SW with (5xG1,2xG2,8xG3,6xL). The 3m x 3m cross has produced 21SW, and 3m x 3f fourteen and its downhill from there.
• A handful of sires have produced more SW through inbreeding, than outcrossing. Of these only Choisir is represented at this sale.

Can Pedigree Racing Index (PRI) help make a selection?

There are eight yearlings in the Sale that are inbred 3 x 3 to Danehill:

Lot No                              Pedigree                      RI score

1274    b f           Smart Missile-Myanma                 91.7

1371   bf f           Choisir-Watabout                          90.0

1484   br c          Teofilo-Feline Flyer                       74.2

1642   b or br c  Your Song -Stage Performer         66.3

1674   b c          Hallowed Crown – Ailish                 65.0

1407   b c         Epaulette – Bantry House                64.2

1419  b f          Your Song -Breezing Home             59.4

1439  b f          Hallowed Crown -Darby’s Bid          59.2

The PRI scores show the Lots 1274 and 1371 have a good chance of being city winners  perhaps even going higher. The others will probably be struggling. Choisir has a better chance than most Danehill stallions to take advantage of inbreeding to Danehill so he would be worth a look. He is probably the fastest of the eight according to my Dosage evaluation.

PRI is a way of evaluation the sires side of the pedigree. To complete your evaluation you need to look at the dam’s side. And don’t forget the physical evaluation.