Kentucky Derby 2015 - Birth Order and the Kentucky Derby
Horse Racing Nation reader Mike B. mentioned in an email that he was told two thirds of the Kentucky Derby winners over the last 50 years were foaled from mares that had been maidens or barren the previous year. The ever curious Mike asked if I would verify or deny this theory.
Birth order and the Kentucky Derby? Sounds like one of those fuzzy articles one would find in the Lifestyle section, right? Wrong -- There’s actually merit to this. Dr. E.J. Finocchio, an equine vet, undertook a study in 1995 about 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 dollars.
Those 689 foals were out of 680 dams. Dr. Finocchio discovered that a mare’s first 5 foals have a better probability of success. The percent of winners were: 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 who were barren in a previous year produced offspring that achieved a better track performance than their siblings.
So what would account for these facts? In the majority of cases, mares are bred to a better class of stallions early in the mare’s breeding career, in order to establish her worth as a broodmare. Although very good broodmares, and blue hens, continued producing high quality runners no matter the birth order.
With that in mind, I reviewed the birth order of the last twenty years of Kentucky Derby winners and identified the following data:
First foal/barren previous year: 50%; second foal: 20%; third and fourth foal 10% each; fifth foal 5%; sixth or greater, 5%.
I also unveiled a trend. In five straight years, from 2000 – 2004, the Kentucky Derby winners were second, third or fourth foals. In the preceding and succeeding years, the majority of the Derby winners were out of maiden or previously barren mares.
So, everyone wants to know what that means for the 2015 Kentucky Derby. Here’s the breakdown:
| 1ST FOAL /BARREN | 2ND FOAL | 3RD FOAL | 4TH FOAL | 5TH FOAL | 6TH FOAL | 7+ FOAL |
| El Kabeir | American Pharoah
| Far Right
| Bolo | Frosted
| Carpe Diem
| International Star
|
| Firing Line | War Story | Itsaknockout |
| Madefromlucky
| Danzig Moon
| Mubtaahij
|
| Keen Ice |
| Stanford |
| Ocho Ocho Ocho | Dortmund | Mr. Z
|
|
|
| Upstart |
|
| Materiality | Tencendur |
|
|
|
|
|
| One Lucky Dane |
|
Horse Racing Nation’s morning line favorite, American Pharoah fits the parameters of the data. Note that his main rivals, Dortmund and Carpe Diem, are both sixth foals. The only two winners of the Kentucky Derby in the last 20 years that were sixth in line or greater were Grindstone in 1996 and Charismatic in 1999, although Charismatic’s dam was barren the year before.
What about the second and third place finishers in the first leg of the Triple Crown?
Second place finishers birth order:
First foal or barren: 30%; Second foal: 15%; Third foal: 20%; Fourth – fifth foal: 0; Sixth or greater: 35%.
Third place finishers birth order:
First foal or barren: 40%; Second foal: 15%; Third - fourth foal 5% each; Fifth foal: 10%; Sixth or greater: 25%.
In nine of twenty Derbies (45%) two of the top three finishers were either out of maidens or previously barren mares.
Just something else to consider as you weed your way through this year’s Kentucky Derby contenders.