My chickens & goats LOVE them. I could grow enough if I devoted at least an acre.

I've often had them grow & flower from seeds thrown out that they missed when feeding. Also, milo will grow well and provide a large seed head that is easy to harvest by just letting it dry and then hanging the head into a bucket, hitting onto sides. You know, they also love pumpkin seeds -- which have been shown to have some deworming properties -- and, they will eat the pumpkin pulp. Whole pumpkins can be stored for quite a while if managed properly.
Another thing I found the chickens loved (surprise to me!) were turnips. Yep. A neighbor had planted LOTS below his fruit trees and wanted only the tops. So, in Dec/Jan he asked me if I wanted the turnips for my goats...still in ground. SURE! I walked back to the site and began pulling these huge turnips. Really, I had 4 front end loads on my tractor. As I filled, drove back & dumped in a pile...planned to cover and use along each day. I chopped them with a machete and found the chickens acted like it was candy! Goats ate them nicely. So, now I grow a few and leave in ground, pull as needed. Need more than I have this year. Didn't get pumpkins in. Trying to get to clear a field from some farmers...always an "after season" thing.
There are several plants, along these lines, to help with livestock feed. I've been saying I want to increase my growing of these for a couple years. Next year I plan to be far more serious as I want to stop working & raising far more of my own feeds will be necessary. Pastures are well established here and I keep working to improve but, other things are needed. With more time to work it, this should be improved over a couple years. Always a work in progress.