In addition to the kennels, our fenced in 'backyard' is approximately 40 yards deep by 90 yards wide. The dogs are given exercise time every afternoon in the yard and have plenty of room to run and stretch their legs.
Behind the enclosed backyard we have an additional 3 acres and although we don't let the adult dogs run loose back there since it's not fully enclosed on all four sides, we do allow our younger pups to run free and it gets them used to roaming out on their own. We find this really helps when we take them on their first hunt with the big dogs. They have already learned to get out and explore on their own and don't tend to hang out with the us as much.