It seems alot of people are breeding just to breed, or make $300 off a stud fee. It's the equivalent of puppy mills. No horse should be bred unless they are proven in performance, confirmationally sound, and have a sound pedigree. The one exception is if you have a horse that cannot be proven in performance due to injury, but has a superior pedigree. We've got 75,000 horses a year going to slaughter in this country. Go to any auction and see who buys the big, fat shiny grade horse...it's not a 4-H kid. Even registration papers don't guarantee a horse doesn't end up a slaughter. There are alot of registered horses, including mares in foal, that get pulled out of kill pens and feedlots by rescue groups. I just love the people that own stallions and "claim" they are proven simply because they have wonderful personalities and they "behave". Just because it has a uterus or testicles, it doesn't have to reproduce.
And just because you have a stallion and have read books, it doesn't mean that you're a breeder or that you have to breed that stallion. Even if a horse is wonderful-it does not always make a good candidate for breeding.