My understanding is that race horse champions are valuable because they can make a lot of money in stud fees. But what about the females? Is there any kind of economic benefit to having a female racehorse (apart from purse prizes, of course)? What happens to the fillies when they retire from racing?
Well, who do you think they breed the studs to? Other studs?
They just get fucked.
“His mother’s a mudder!”
What I’ve asked here before, but never got an answer, is why male horses can’t breed and race at the same time. Why couldn’t American Pharoah moonlight as a stud next year and still run races? Also, why can’t they artificially inseminate the female horse instead of setting up these rendezvous?
They can’t artificially inseminate female horses because it is against the rules. Thoroughbred horses cannot be registered if they were conceived by artificial insemination.
Right, but males can breed with lots of females, while the females can only breed once a season. So economically, it seems like a female would not be nearly as appealing as a male as far as return on investment.
You don’t breed them until they’ve proved their value as a stud by winning races.
You don’t run them in races after you turn them out to stud, because they can break their leg, and then you have to destroy a valuable stud.
As noted upthread, you can’t just freeze their sperm and use it later, because thoroughbreds have to be live bred.
It’s quite logical once you break the answer into pieces.
Don’t the pieces also have to be logical? What’s logical about making artificial insemination against the rules?
With artificial insemination one stallion could, theoretically, sire the entire next generation of thoroughbreds, leading to potentially catastrophic inbreeding.
Without artificial insemination it limits how many mares any one stallion can impregnate, limiting (though not completely eliminating) inbreeding and incest.
Thoroughbreds already have a limited gene pool, making it smaller would be stupid.
If they’re concerned about inbreeding, they should make rules about inbreeding, not artificial insemination.
Why do you object to the no-AI rule? It serves a purpose. It may not be a method you would choose, but it does limit the inbreeding.
Also by limiting the number of mares a stallion can cover, it opens opportunities for other stallions to breed. Win for other breeders and stud owners.
Fillies become brood mares. Sometimes they also end up as riding horses, lawn ornaments or dog food. Geldings, and there are lots of them winning, too, only get the last few options.
Exactly. And you can make more money in stud fees than you can in racing. So why take the risk?
Also, one reason for live cover that hasn’t been mentioned is the possibility of fraud. When you pay a big fee for American Pharoah, you get American Pharoah, which is easy to confirm (all thoroughbreds have lip tattoos identifying them).
If you’re handed a test tube full of sperm, that’s harder to confirm; until DNA testing became available, it was impossible.
So if AI were used, the possibility for fraud was strong, You can make a lot of money in stud fees, so why not start using sperm from another horse and increase your profits? Or if your horse dies, why not say you still have frozen sperm available? People would end up paying for a $10,000 champion and get sperm from a $200 claimer, and would have no way of knowing.
Yes, though the market on stud fees would take that into account to a certain extent.
Breeding the female would also be riskier; you have to pay a stud fee, and if nothing goes wrong–you get a foal. Who could grow into a very valuable horse, or maybe not. 
I asked a friend who dabbled in race horse ownership about the artificial insemination thing. He told me it’s not a big deal because of the limited number of thoroughbred horses and doing it the old fashioned way was sufficient. Virtually every thoroughbred alive is descended from past champions, it’s not hard to spread their genes through the population. Sounds kind of reasonable, but I don’t have a number for the current thoroughbred population to see if it really is.
ISTM that this makes sense if the question is “why not continue to race them while they’re being used for stud?” But the question is “why not use them for stud while they’re continuing to race?”
American Pharoah would presumably have quite a bit of value as a stud long before his final race. But he’s still racing and taking the risk of broken legs. So why not use him for stud at the same time?
The reason for live cover breeding is the romance of horse breeding. If you could have artificial insemination the the horse breeders would be reduced to factory farmers. All this talk about in breeding etc. are after the fact justifications.
That said the thoroughbred people point to problems with quarter horses to show that artificial insemination leads to problems. Quarter horses can be bred with artificial insemination.
Sure, but not the night before a big race.
My WAG is that all the high-stakes races are for three year olds. During that year, the horse is establishing his value as a stud, not only by winning, but by racing against the best horses in the country. But when the horse hits age four, he’s no longer eligible to compete for the big purses, the level of competition drops, and it isn’t worth risking millions in potential stud fees for smaller and smaller purses in races that don’t prove anything.
Someone who’s more familiar with the ins and outs of thoroughbreds is welcome to tear holes in that theory.
Funny you say that because that was my pet theory. Once a horse has experienced the pleasure of sex, maybe the “motivation” to run fast goes away?