3-4 days in with the female. 3-4 days out to rest and feed.
Continue this until the female ovulates.
Females can breed every year as long as they have good body condition. If they don't want to go, they will skip the year themselves.
You can also choose to give them breaks every few years if you want.
Usually males can breed fine to 4-5 females in a season as long as he maintains good health and body condition. If he looses too much weight, I would pull him from breeding. You don't want to stretch your males too thin.