Birth Order and the 2023 Kentucky Derby

Surprisingly, there’s merit to the birth order of Kentucky Derby winners.

Birth order and the Kentucky Derby? Sounds like one of those fluff articles in the Lifestyle section, right? Wrong. There’s merit to this.

Dr. E.J. Finocchio, an equine vet, undertook a study in 1995 about the birth order and success of the racehorse. Dr. Finocchio studied 689 horses that won either a Triple Crown or Breeders’ Cup race; earned an Eclipse Award or over $1 million.

Those 689 foals were out of 680 dams. Dr. Finocchio discovered that a mare’s first five foals are more likely to succeed.

The percentage of winners was:

first foal (16.9%)

second foal (21.5%)

third foal (18.6%)

fourth foal (15.3%)

fifth foal (10.7%)

sixth foal (8.1%)

seventh foal (6.4%)

tailing off to 1.5% for the 13th foal

In addition, David Dink and Frank Mitchell undertook a study of their own, which was discussed in Mitchell’s book, “Racehorse Breeding Theories.”

They ascertained that mares barren in the previous year produced offspring with better track performance than their siblings.

So, what accounts for these facts? In most cases, mares are bred to a better class of stallions early in the mare’s breeding career to establish her worth as a broodmare.

Outstanding broodmares and Rene-de-Course (blue hens) continue to produce high-quality runners regardless of birth order. Secretariat was 14th in line, had six older blacktype earning siblings, and two were born after him.

Admittedly, Dr. Finocchio’s study was a small sampling, but the results were promising.

So, with that in mind, I researched the birth order years of Kentucky Derby winners back to 1980 (counting the DQ’d winners Maximum Security and Medina Spirit, for a total of 44 winners) and identified the following data, rounding up for .51% and greater:

Kentucky Derby Winners

First foal: 20%

Second foal: 18%

Third foal: 7%

Fourth foal: 11%

Fifth foal: 14%

Sixth or higher: 15%

Total Previous blacktype siblings: 34%

Barren previous year: 20%

 Seven contenders whose birth order was sixth or greater had stakes-winning siblings.

What about the second and third-place finishers in the first leg of the Triple Crown?

The eye-opening fact was that 93% of the Derby runners-up who were sixth or higher in birth order had blacktype earning siblings.

Second Place

First foal: 9%

Second foal: 14%

Third foal: 21%

Fourth foal 14%

Fifth foal: 7%

Sixth or higher: 33%

Sixth or higher blacktype siblings: 93%

Total Previous blacktype siblings: 41%

Previously barren: 22%

 75% of the show-spot finishers who were sixth or higher in birth order had blacktype earning siblings.

Third Place

First foal: 11%

Second foal: 29%

Third foal: 14%

Fourth foal 11%

Fifth foal: 5%

Sixth or higher: 29%

Sixth or higher blacktype siblings: 75%

Total previous blacktype siblings: 41%

Previously barren: 26%

Which of this year’s Kentucky Derby contenders fit the profile?

 

Birth order is something else to consider as you weed your way through this year’s Kentucky Derby field.

The Derby Guide has the birth order for each Derby contender, as well as pedigree, how they might handle mud, how they worked out, speed figures and other vital info that nobody else offers.

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