Breeding

At what age (or ages) do most people breed their horses? Do most players breed just once, or multiple times per mare? I apologize if there is already a post discussing this - I haven't seen one!

Some people I've seen breed them until they are about 14-16 years old

Usually people breed their horses 3 times at ages 18, 19, and 20. So they can get foals with the best stats.

At the earliest I breed at 14, 16, 18, 20. Now though I'm experimenting with starting at Sixteen to do my first breeding. 

16-18, two or three times. Depending on the stats of the horse, I breed them more if they have high stats usually.

I normally don't start breeding my horses until they're atleast 16, and get 1-3 foals from them.

For my stat based projects I breed my horses at 18, 19 and 20. Sometimes only the last two if I'm not after as many foals from them. For my colour based project I plan to start breeding at about 15 or 16 so that if I don't manage to get the genes I want I get a few more tries at it. I expect I'll sell about half the foals.