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Last week saw the running of the Epsom Oaks (Eng-I) and Derby (Eng-I), two of the longest existing classic races in the world and for many the barometer of the Thoroughbred breed.

The Derby was won in devastating fashion by the royally bred Australia. A son of the good racehorse and now leading sire Galileo (TrueNicks), Australia is out of Ouija Board, one of the finest mares ever to look through a bridle. Rated an A++ on TrueNicks on the basis of Sadler's Wells and his sons when mated to Cape Cross mares, Australia is the only stakes winner specifically for Galileo out of Cape Cross mares, with four other runners bred on the direct cross.

Victorious in the Oaks was another well bred filly in the undefeated Taghrooda, a first-crop daughter of the out-and-out champion Sea The Stars. A half brother to the aforementioned Galileo, Sea The Stars was high on expectation as a stallion. The detractors were out after his 2-year-olds hadn't shown much last year, but the performances of his offspring as spring 3-year-olds looks to have put those concerns to bed. Also A++ on TrueNicks, but on a different calculation rule, Taghrooda is out of the stakes-winning and group stakes-placed Ezima, a daughter of the leading sire Sadler's Wells.

Anyone with decent observational skills will have seen that Australia and Taghrooda have a lot in common—three of four grandparents to be exact, Cape Cross, Sadler's Wells, and Urban Sea.

It is worth taking a look at the number of times that we have seen these three horses appear as the grandparents of horses that have raced. Galileo of course has a full brother in Black Sam Bellamy (TrueNicks), so there are a few more observations for us to make given that the names on the page are the same (Sea The Stars doesn't have a runner out of a mare by Sadler's Wells' brothers Fairy King or Tate Gallery). Here is the list of runners sorted by their current Class Performance Index (CPI).

Now while the data is admittedly limited, and we are assessing the race performance of many of the Sea The Stars progeny well before they have had a time for their career to flourish, there are a couple of observations that can be made.

1. Racing class matters. The race performance, as measured by the CPI is relatively constant between the sires although Black Sam Bellamy was not quite as good a runner as his brothers, but it varies between the mares. Generally speaking a CPI above 7 represents a horse of some merit and it is noteworthy that the two best horses with the combination of ancestors are out of mares that could really run.
2. Genetics goes to show that even with the best of blood full relations can be wildly different. Australia won the Derby, but his full sister, Filia Regina, only broke her maiden in a 14-furlong race at Yarmouth.

Filed under: Pedigrees and Breeding, European Racing, Pedigree Elements, Inbreeding, Unique Ancestors