Invasive plants are Earth's way of insisting we notice her medicines. Stephen Herrod Buhner
Everyone learns what works by learning what doesn't work. Stephen Herrod Buhner
If you can build your own compost from manure, food waste, and mulch, the chickens will thrive off of this, supplemented with a little hay and a mineral supplement.
The end result will be an even richer compost you can sell for potting soil or use in the garden, and you would have no feed bill.
The chickens would basically be living and feeding on your finished compost pile, which you would add to every day, while mixing fresh material in a separate pile to start decomposition.
Millet, beans, sunflowers, and squash are the main ones I'm focusing on. I'm debating whether to dry some green leafy stuff for them, or grow fresh all winter in the form of sprouts.
What I'd really love is to have a walking stick kale growing as a potted plant inside the house. But I'm pretty sure my cats would have other ideas about how such a plant should be used.
Sunchokes are handy because you harvest them in the winter. Just dig what you need to feed each day (or week). Lots of nutrition and they enjoy having something to peck at.