I just turned my existing dog pen into my new chicken pen, plus a coop for them. I have 2 RIR's, 3 Barred Rocks, and 2 White Leghorns, all of them hatched in August this year. My pen is 25' x 25', it has quite a bit of grass and clover in it right now. How much feed do I need to be providing for them? So much per bird, or just a feeder full 24/7? Any thoughts appreciated.