Ferment your feed. But also, lots of scraps. You'd be amazed how little they can't have.
Discussion
Do you just cover the feed with water for a day or two? Yes, I have fed them some gross stuff and they know what not to eat. Someone told me to not give them onions, but they just don't eat those from the scrap bucket. I figure it adds to the compost anyways.
No such thing as a free lunch but there are some beneficial hacks to try. I dont always ferment but i do soak grain. It expands and so the birds gorge themselves less. Free range s much as possible will benefit more than anything but then you deal with predationand typical damage that chickens do. eg. Getting into gardens and scratching...
I plan on building a run on a hill for compost production. Carbon, weeds, food, ect... get piled at the top. Chickens add nitrogen and move it downhill. I think I will let them out for a couple hours because I want them mostly working the compost. Not sure if I will do a couple paddocks or just let them free range and fence the garden. Once the grasses and weeds grow big enough I'll get the scythe out for material.