If you get the shallow planting trays that have holes in the bottom for drainage, you can set up and plant a BUNCH with various blends of grains, such as oat, barley, wheat, pasture mix, clovers, etc. It can really be done with almost any greens plant, even carrots and so forth. Just make a small raised cover of hardware cloth for each about 2" above soil level, so the chooks can eat down to the wire but NOT rip up the flat itself, and rotate them out as needed.
The cover has to be on while the plants grow, so the stems go through it and the roots are protected. Of course, you can always grow them and harvest by cutting regularly and feed in a hopper, too, but the girls here seem to prefer the whole 'I GAWT IT, yank, yank, flip over backwards when it gives' process.
Amaranth is an EXCELLENT feed plant and some varieties will yield up to a pound of grain per plant. Amaranthus cruentus, I believe, is the species that is most often grown for grain. It's fast, it's easy, and loves the heat of the summer.
Millet is another one that chickens like--you can grow the thick-headed type like you see in pet stores and toss whole dried heads in for them to argue over. Good entertainment and decent feed value.
This year, I'm planning on converting my back porch into a lit growing area to help feed my 100-or-so rabbits and the chickens; it will be interesting to see how well that works.
On the grow list:
Alfalfa
Barley
Oats
Wheat
Broccoli
Kale (chickens only)
Amaranth
Carrots
Parsley
Celery
Fruitless mulberry (large pots, coppiced bushes for summer forage)
Beans
Peas
Turnips
Radishes
Beets
I'm sure there will be others but this is plenty for now!
I do want to find out if chickens and rabbits can eat passionfruit--the neighbors' vines are taking over the oak trees and there's LOTS to go round.
I also raise mealworms (which are doing remarkably well despite cooler temps than ideal) and redworms (compost worms, under the rabbits) but the darn chickens largely destroyed my worm beds over the last year or so.
Since they are now confined and not happy about it, perhaps the beds can recover now....and if they do, I can harvest and dry in summer for winter protein supplementation.
Sure wish the rabbits would eat the mealies and earthworms....or at least the chicken eggs! Hm...*kicks brain in gear*...gotta be a way, right?