All of the time. He has a dog door and comes and goes as he pleases. Chickens are out all day. He comes in and sits on the floor for an hour or so and goes out to check on them and comes right back in and naps.
My pitbull is around my five free range girls unattended all of the time. He's interested in the new chicks but only to smell them. He only 10 months old and he does a pretty good job of protecting them.