Can anyone tell me why it is that in the likes of Thoroughbred breeding, the majority of the focus is on stallions? I mean...when I look up pedigrees, stallions are always named, but mares often aren't. Mares often have "Mare by..." or "...Mare" or even "Sister To..." where a name should be.

Example: http://www.allbreedpedigree.com/mercury

Hmm.. I'm certainly no expert, but all I can say is because mares weren't usually often as valued as stallions. There's many more famous stallions than mares. Regret was the first (out of the current 38) fillies to win the Kentucky Derby (1912). The Derby was started in 1875, so 42 years until a mare won. I don't believe a mare has ever won the Triple Crown either.

I think because of hormones, mares were often hard to handle at times and had unpredictable performance. So people usually used them as broodmares. I think in recent years, now that we can control a mare's hormone regulation with things like ReguMate, mares are becoming more prominent in races and other competitions. 

It may also just be simply that following a stallion's lineage is easier. You usually read about a "Foundation Stallion" (or 3) of a breed because stallions can be bred repeatedly, while a mare's gestation lasts almost a year, and she usually just has 1 foal. When you're starting a breed, you want to have as many foals born as possible so the breed can increase exponentially throughout time. Therefore, even though you get further and further from the Foundation Stallion(s), you still want to trace the pedigree back to that foundation stallion, while unfortunately, the foundation mares and other broodmares may not have been so important to note. Especially if they hadn't been famous or noteworthy. 

But this is all really just speculation on my part XD

It's a lot to do with genetics. The stallions are also stronger and faster a lot of times. You will see the same with AQHs and other big breeds.

Like Sass, I will certainly disclaim that I am not an genetics expert by any means of the imagination, but I have known two people who bred them and went to an actual Thoroughbred farm in November who actually discussed this question to another person who asked this {I just have to hope I retained it all}. Below is the long lecture that we were told and the other two breeders have backed this, now whether this is true or just their method in particular has yet to be disclosed.

From what they told me, they said that stallions have much more value than female horses for several different reasons, which both Farewell and Sass emphasized. The first reason is build and genetics; stallions have a lot more strength, speed and resistance that females on the track do not. They state that stallions are less likely to break down on the track than females, giving them more of an advantage. The second reason, which Sass pointed out, is temperment. While some stallions can be feisty, they are still very easy to control and keep in hand, but females back in those days were considered more dangerous and less easier to be controlled as horomonal medications like she said did not exist back then; Mares/fillies dominating the fields now are a recent occurence due to this. Finally, the third reason - and for any breeder, the most important - is breeding. Mares are considered to be "seasonal breeders" due to the fact that they are only interested in breeding when in estrus, where a stallion can sire much more frequently. Many breeders, especially thoses of champion pedigrees, want to sire/foal as many future generations as they can before their horses die to continue the line. Due to that seasoned breeding, unless it it was medically stimulated in some form, there would be big gaps that many breeders look down upon.

The reason that pedigrees say "Sister to" or "Mare of" represents the overall value and fame of the secondary horse. For example, we're all known of the 2016 Triple Crown champion stallion, American Pharoah; he actually has a half-brother named Classic Empire. Because Pharoah is an overall champion, that adds a small value to Empire in addition to any wins that he has received so, for mares/fillies, it's a very similiar concept. Finally, like Sass also said, many people prefer using mares as broodmares and want to add value any way they can and having champion bloodline relation or consecutive wins is the topping on the cake. A good mare in category would be the famous Zenyatta, who won 19 out of her 20 career races and became the first female to win a Grade I Breeder's Cup Classic. This already adds a lot of value to her due to this, so her dam, Vertigineux could be refered to as "Mare of" to her daughter.

Now, again, whether or not this was just some colorful story they wanted to spin or it's actually legitimate breeding practice, I do not know, but this is exactly what I was told.

Also not an expert, but I think the main reason is that Stallions can be bred a million times and it won't affect their racing career at all. A mare can only be bred so many times, and when she IS bred, she's pregnant for 11 months, then is still out of commision during recovery and weaning of the foal.

So, imagine she starts racing at 1 or 2, and it maybe takes 5 years of solid winning to get a real "name" going for herself so that she's valuable as a breeder. At this point she's likely 7. So if they take time off for breeding, that can potentially take 2 years out, and then she's 9, which is generally too old for race tracks. So maybe she can be bred 3 or 4 more times in her lifetime, if they're lucky?

Whereas a stallion can be bred for it's entire life, over and over, with no real effect on their career. MAYBE it takes one day because Thoroughbreds have to be bred "naturally" and with witnesses in order to be registered.

Not to mention, there's a LOT more risk involved with breeding for mares. They could potentially be hurt during the breeding itself, or die while foaling, and then that's millions of dollars down the drain for her owners.

Thanks for the info guys! I see what you mean about the stallions being able to breed more often and the other points made. Now it makes more sense. lol I still kinda feel sorry for un-named mares. Haha!

This was a interesting post, I enjoyed reading the answers! Learn something new everyday.

Paints since 6-8-14

For what it's worth, this is part of why mare points are worth more to foals on HP. To even out the injustices of the world :P. And also because the mother arguably has more influence over the foal since it's getting nutrients and learning it's first things from/with her.

Just a tidbit...now a days seregate mothers are being used...i know this from a high dollar arabian farm we visit to see the babies.

They do embryo transfers now. So technically mares can have babies without being pregnant.

Most people believe mares have more heart and try as well. Geldings are usually lazy.

But ive always had quarters,arabs and paints, so this could be different for tbs!