Mare

How Important is the Mare
in Sport Horse Breeding?

Understanding your breeding stock's genetic strengths and weaknesses can be the greatest tool you have in your quest for sport horse excellence. Recently a recognition of the power of the mare has become a focus in equine breeding. Although the genetic contribution of both parents is very important, a realization has surfaced that the maternal strength might instead be responsible for more of the foal's attributes.


The discovery of the large heart gene, a sex linked trait, was one exciting example of this. Another instance is the advances that have been made into Mitochondrial DNA research, both in humans and equines.

"Around the globe you will see the most successful farm operators active at acquiring quality mares and fillies, they know maternal strength is the pathway to success."(McLean)

The Thoroughbred industry has noted that sustaining traits for speed have come most reliably up the female lines. Read about a modern example of mare power in Big Brown.

It took them quite a while to get to this point of view. In the early days of the stud book mares seldom got a name of their own, more often they carried names like "daughter of Glencoe" or "Sedbury Mare" identified only in relation to their sire. This had made the study of early Thoroughbred pedigrees difficult. It is worse trying to study Warmblood and Sport Horse lineages- often the mare is just "unknown".

Knowledge in any field comes from the hard work of many people. The advances in equine genetics and breeding are no different. Following are just a few of the "giant's shoulders" we are standing on today.

Frederico Tesio, the father of balanced linebreeding, was an intuitive genius, instinctively he choose broodmares with reserves of nervous energy- this was long before Mitochondrial DNA was ever imagined.

Ken McLean in his "Genetic Heritage" announced the importance of the dam's x chromosome and he anticipated the future findings in Mitochondrial DNA.

Bruce Lowe attempted to trace and classify those female families that were potent for racing excellence in a number system that is still in use today.

Clive Harper gave us the statistics that have clearly shown that sex balancing pays in his "Thoroughbred Breeders' Handbook" and then explored the power of the mare in depth in his "The Thoroughbred Broodmare Book".

Marianna Haun thrilled us with her "The X Factor" which traced the large heart gene coming down the x chromosome.

The above is a partial list, but enough for you to see that all of these ground breakers were ON TO SOMETHING.

What does this mean for the breeders of Sport Horses? Briefly, because equine genetics work the same no matter the breed of horse, we should employ all the knowledge the Thoroughbred Industry is providing. In particular, we should make breeding decisions with an awareness of the strength of superior mare lines- and we should take steps to bring forward this power to our sport foals.

Just as in human research, the equine researchers are able to trace the Mitochondrial DNA back and determine true ancestry. This is a huge help now, and will be even more in the future, when we will be able to fill in those gaps in our sport horse pedigrees. For example, it was discovered by this method, that the general stud book (Thoroughbred) had far fewer foundation mares than they originally thought. And it also turned out that some of the foundation mares were recorded several times, but with different names, plus many of the mares were also found to share a common mother. This should be an exciting period for all breeders of horses.

It is well established that proper energy conversion in the cells is essential for good muscle performance. As breeders of horses that we hope will excel in sport we should pay close attention to any new developments in Mitochondrial research.

We can capitalize on this science by making an effort to understand the proven mare lines our stock may carry. This will be easier for some breeds then others. For instance, the Holstein Association has always put an emphasis on "stamm" lines (maternal families), and therefore the genetically potent mares will be relatively easy to identify. The Trakehner Horse is another breed that has valued its exceptional female lines, to the point that the stallions are named by the first initial of the dam's name, rather than the other way around. Thoroughbred breeders have classified especially potent mares as "blue hens" and Ellen Parker has developed a "reines de course" list and made an in depth study of the female families. With other breeds it may be harder, but not impossible.

Abiza, an example of an excellent broodmare, she gave birth to multiple champions including the Olympic Silver Metal winner in show jumping: Abdullah.

Asher- a sport stallion with sex balanced inbreeding to Abiza

To identify good target mares for you linebreeding, look to broodmares who have more than one excellent offspring. One example is Tabelle (Holstein) a mare who is dam of 6 stallion sons! Read more about Tabelle's sons. Another good example is Sendernixe (Hanoverian) the dam of a dynasty of stallions: World Cup I-V. When you have identified a mare in the pedigree you believe is a good subject, then look for her siblings (full if possible) or her sons and daughters in your mating choices. A German breeder used a dam who carried the genetic sister to the above mentioned Sendernixe, this was Seeluft, when he bred to Weltmeyer (grandson of Sendernixe). The result of this doubling up of these 2 sisters was the stallion Welthrum, a horse that almost equaled his sire's dressage index by scoring an incredible 144 in his stallion test.

Once you have found a good mare line in your gene pool lineage, make that mare one of your linebreeding targets. This is what the successful Thoroughbred breeders are doing - they are linebreeding to dominant mares- with spectacular results.


Case Study- The dynasty of Enniskeane Countess

Great maternal influences are much harder to find then those coming from stallions. Mares only produce an average of 5-10 foals in their lifetime, compared to a stallion average of 250-500 offspring. So, any mare that has more than a few good progeny is a mare to treasure.

Clive Harper, Thoroughbred pedigree expert, said: "Start with what strength the mare has- always looking very, very closely at the dam line- and build in the complimentary and supplementary names."

One of the most productive practices you can assume in your breeding program is to build up powerful broodmare famiies.

(Article first published in 2005 on the Sport Horse America Website, edited and enlarged for 2007 here)


Link to Mumtaz Mahal - a Thoroughbred Mare with that is Hard to Ignore.