I feed my three steamed rolled oats and sunflower seeds, plus the kitchen waste, bugs and other forage they find: they are slim, so your broilers may not be very meaty, but they will also have very low fat, which I see as a plus...
I had an Amish chicken in NY that I used for soup: it had the most wonderful flavor and no fat floating on top, versus the bland flavored store bought chickens and their 2 to 4 inches of fat on top of the soup.
You do not post where you live, but you can grow a tree called Moringa Olifera that you and the chickens can eat. The chickens can have it as 1/4 th of their food if it is dried leaves, so more if it is fresh... Look on youtube for a documentary by Discovery on the miracle tree. It is packed with nutrients, needs little water, and makes a sustainable harvestable crop. You can eat the leaves, eat the seeds, make a high quality oil for cooking and machinery from the seeds, use the seed shells to purify water, and eat the pods like green beans when they are young. It will make seeds when it 8 months old.
If you are in cold area, you can grow it like an annual, or keep one in a big pot to move indoors when the cold comes.
My seeds sprouted and within a week they have branches with leaves. In three months you can harvest and it will regrow. In one place in the documentary they planted seeds 3 inches apart and cut it halfway down.
I tested to see if my chickens would eat it today, and they did.
I tried it, too: in a very young leaf the flavor was really nice: like a very fresh green, slightly sweet, just a hint of spiciness, and a barely noticable horseradish aftertaste.
