Are Female Families Really That Important?

Female Families Numbers Explained

To allow this topic to come full circle, please forgive the initial history and science lessons. I promise that I will eventually get to something practical and/or useful!

The Family Numbers commonly used to designate the various Thoroughbred female families were popularized by Bruce Lowe, an Australian pedigree researcher at the end of the nineteenth century. He had traced back the pedigrees of the complete list of winners of the oldest English classics (the St. Leger Stakes, Epsom Derby Stakes and Epsom Oaks) grouping them by direct lines of tail female descent, from dam to grandam and on back until the family was no longer traceable in the General Stud Book. He then tallied the number of classic winners produced by each family and listed them in declining order. The family with the most classic winners, the one descending from Tregonwell’s Natural Barb Mare, was designated Family #1, the Burton Barb Mare second, designated Family #2, and so on. The resulting forty-three numbered families became the core of his study, and while few actually adhere to Lowe’s resulting theory, many still use his family numbers as a convenient way to categorize Thoroughbred families, self included.

Today, the families established by Lowe have been expanded to include families no. 44-74. Other groupings of mares were also added to incorporate the global nature of the Thoroughbred. They are classified as follows:

• Families 1-50 – Bruce Lowe’s original numbered English families traceable to the earliest volumes of the General Stud book
• Families 51-74 – Can be additionally traced to General Stud Book mares
• Families AR1-AR2 – Native to Argentina
• Families P1-P2 – Native to Poland
• Families A1-A37 – Native to America
• Families C1-C16 – “Colonial families” native to Australia
• Families B1-B26 – Designated as “Half-bred” due to some impure crosses

Whether one agrees or disagrees with all of Lowe’s theories, his family numbers have given researchers the greatest tool possible to seek out similarities in pedigrees. Along with knowledge of the major breeders and their best sires and dams, family numbers give us the best possible information to seek out linebreeding patterns in today’s runner.

Chromosomes and Heart Size

This is a complex subject, so I will just keep it to the basics. Genetic factors and gender biases can be found in the X- and Y-chromosomes. These are the chromosomes most directly involved in gender. A stallion (XY) has one of each chromosome. A mare (XX) has two X-chromosomes and will always pass one of the two on to her progeny. The stallion is always the determinant of the gender of a prospective foal. If he passes his Y-chromosome, the resulting foal is a colt (XY); if he passes his X-chromosome, a filly (XX) will result.

Now let’s add in the X-Factor Theory into the equation. The X-Factor Theory proposes that a mutation within a gene located on the X-chromosome of females causes a larger-than-average heart. Unlike humans, a large heart in a thoroughbred is a good thing. It gives the horse greater stamina and strength. So, if all if this is true, X-chromosomes, female families and greater heart capacity go hand in hand. They are extremely important in planning matings or analyzing pedigrees of potential racing stock.

One classic illustration of these two points is that of Secretariat. The post-mortem discovery of his huge heart size is legendary. In all his greatness, Secretariat was not an outstanding sire, nor a sire of sires. But, his daughters made him an exceptionally fine broodmare sire producing the likes of Storm Cat, A. P. Indy and Gone West just to name a few. Again, when daughters were produced, he passed his female chromosome.

Racing Families and Sire Families

Lowe’s theory went far beyond identifying female strains. Of these families, he found that nine in particular appeared to be “indispensable” in the breeding of top racehorses and he divided these into two classes, running (family #’s 1, 2, 3, 4, and 5) and sire (family #’s 3, 8, 11, 12, and 14) or as Lowe perceived them, feminine and masculine, respectively. His theory was based on balancing the “feminine and masculine factors” by using these two classes of families as “core” to good matings and essential for successful breeding. Note that Family #3 is in both groups. Lowe considered it able to produce both good runners and good sires. I call it a “dual-qualifier” and can be exemplified by A. P. Indy (3L) and Tapit (3:o).

I have added female family #13 to the sire list in my analyses now making it read 3, 8, 11-14. Family #13C alone has produced the likes of stallions Darshaan (GB), Seattle Slew, Mr. Prospector, Siberian Express, Le Fabuleux (FR), etc.

OPTIMAL Matings and Female Families

An OPTIMAL Mating is a comprehensive snapshot of a seven-generation pedigree that incorporates seven time-tested breeding theories and gives breeders the greatest opportunity to breed a superior racehorse. No single theory is capable of achieving an exceptional runner with every breeding, but occasional success is expected. Therefore, I demand that all seven theories are satisfied within each mating or pedigree of a potential purchase.

My very first step in analyzing a pedigree is to consider female families. I designed the mating of multiple Grade 1 stakes winner Mor Spirit for a long time client. Since I am familiar with the pedigree and for hopefully a better illustration for you, let’s look at his pedigree below:

We all probably have characteristics and/or mannerisms that most reflect one of our four grandparents (2nd generation). Horses are no different. That said, I focus on the two female families located in the 3rd generation that make up each “grandparent”. That creates eight different individuals consisting of eight families. Genetically, we can’t determine the path in advance that nature will take. We can’t even definitively say that the direct female family will come forward even though this is one of our main commercial concerns. But, we can examine and reinforce quality families in hopes that the best ones come forward.

This is where female family numbers, running families, sire families and, to a degree, X-Factor Theory come into play. In analyzing tens of thousands of stakes winning pedigrees, I have determined that the greater majority of stakes winners have at least one sire family and four running families in their 3rd generation. This is my baseline. If I can’t satisfy this first pedigree factor, I’m on to the next stallion for a mating or the next page of a sales catalog.

Let’s look at the individuals and female families in Mor Spirit’s 3rd generation:

• Storm Cat – female family 8C
• Mariah’s Storm – female family 11
• Seattle Slew – female family 13C
• Altair – female family 2D
• Dixieland Band – female family 4M
• She’s Tops – female family 4M
• Allen’s Prospect – female family 4M
• Sequins – female family 1N

Based on sire families (3, 8, 11-14) and running families (1-5), Mor Spirit has 3 sire families and 5 running families in his 3rd generation (1 and 4 minimums required). Coincidentally, all 8 families represented here are what Bruce Lowe termed “core” and “indispensable” families.

Female families are just one of seven factors I use in determining an OPTIMAL Mating. All of my pedigree analyses start and most stop with female families. Yes, they are really that important!

Whether you are new to the game, experiencing more losses than wins or just looking for a new approach, I am confident that I can help you breed or buy a better racehorse. To find out more about OPTIMAL Matings and how they can help your program, please subscribe to my Blog/News page HERE to receive future information on complimentary mating recommendations, sales short lists, stakes winner pedigree analysis, news on personal client success and any other random thoughts or ideas that I may have. Also, receive a complimentary copy of my report “Blind Luck or Designed Luck? – How A Kentucky Derby Winner Was Bred” sent directly to your inbox.

For inquiries or more information about Shepherd Equine Advisers, please contact Clark Shepherd at 859-321-6618, or by email at clark@bloodstock-agent-ky.com.

I would love to hear any comments or questions that you may have. Please submit them below. Maybe we can address them in a future post!