I have read about people doing small-scale haylage or grass silage for small flocks of chickens. I see no reason that corn silage would not also work, but you'd have to ask your chickens what they think - get a bucketful from a neighbor if you don't have any on hand before you head down that route.
This page (if YT does not munge it) reports on silage/haylage, and I note that Alfalfa has as much or more protein as standard chicken feed at any stage:http://www.ag.ndsu.edu/pubs/ansci/dairy/as1252.pdf
Myself, I generally gave in to simplicity and bought feed when I had birds. They certainly like their storebought feed better when it's been fermented for a few days into sour mash. That speaks well of the odds they will like other fermented forage.
I think if "normal" feed is available in case the haylage is not up to snuff that would be fine - otherwise you need to get into testing to be sure you're providing what they need.