Wow I would love to give so much space to my Marans. I make it up to them by free ranging them as much as I can during the summer months. My husband and I are currently working on fencing in our entire property so I won't have to worry about my chickens getting slaughtered by rogue dogs. I love that you are able to keep your birds on grass all the time.
Which leads me to a question: what is a good grass alternative? Will chickens eat dry bales of alfalfa hay? Our feed mix has alfalfa pellets in it. I feed as much fresh produce as I can get, but I hate I can't do it daily. Our current feed mix is 18% protein and consists of corn, laying pellets, calf manna pellets, alfalfa pellets, wheat, milo, and black oil sunflower seeds. I supplement with crushed egg shells and crushed oyster shells also. We try to keep fresh straw in their coop to scratch, especially during wet periods.
As soon as we get the time, I am going to work on some grass frames for the coops so that will help.