Now this is assuming that one can not let their chickens free range due to npnd (nosy people next door). And/or its winter time and the ground has turned in to white mtns..
You can feed fish to them as treats.
Same with hunting. What you don't want, they will eat.
I know some ppl that pressure can those bits and pieces for their dogs..so why not for chickens.
Grow winter squash. It stores very well over winter if cured well. I have had mine stored for a good 2 years and they were fine. It's very good for them, along with the seeds.
You can plant pumpkins as well, but they will not last thru out the whole year in storage, at least mine never did. Possible, I guess, to dehy. Then soak to bring back to life..?
Peas..high protein..grow, dry and store for them.
You can also dry corn and husk for them or serve on the husk...which ever suits you.
Swiss Chard..again excellent for them. Dehydrated and store in closed jar for winter feeding.
I sprinkle it over mac/spag./rice/oatmeal (cooked) or what have you that's damp and sticks to it. Great for winter time feeding when, like us, they crave greens.
Plant sunflowers and feed that to them come winter...sparingly. They don't need to get to fat on those. Its like candy to them and they will pig out on only that, if you mix to much in with your grains/hen scratch.
There is more, but that's a start.
Feed extra eggs back to them. Boil 'em up, cool them down, crack them against something, then stand back before tossing to them.
I have also made 'omelets' on real cold days for them, add in crumbled S.chard, a real good sprinkle of c.pepper.
I have mixed in left over from the nights before meal....of rice, corn, peas, any tiny bits of meat/fats, pieces of bread, etc.
Crickets....you can raise your own to feed to them. Search the net for info. on raising them.
Then there is worm raising.
Or dig around in the compost pile, if you compost.
I put some old boards down in their runs, then every other day or so in summer, I will turn them over.
I think after the SHTF is bad enough to close down stores or cause massive shortages, the 'ppl next door' will not complain if you have a roo to look after the hens. They will be only to happy to get eggs once in a while!
They might even get a little concerned if they don't hear that roo crow, knowing that will bring more chickens then eggs your way or their way.
After all when hatching, there not all hens. Those extra roos will be invited for a meal I am sure.
Also extra roos and hens might just make for a great trade item in SHTF times. Mind, you might have to do some s'plaining to do about the facts of life..that is chicken life..to those folks.
Winter time growing a few plants of leaf (not head) lettuce and/or s.chard is also an idea for both you and your feathered friends. It grows pretty fast and doesn't need a whole lot of light.
I feel in summer they do not really need extra hen scratch/grains, only need layer pellets, they can find their own treats/grains/weeds.
Course in summer time there is weeds and what nots to toss to them if they cannot be free ranged for their own grub.
A sense of humor is absolutely essential to survival.