Where it is REALLY cold this won't work in dead of winter but, early Spring will....I've taken old bales of hay or wheat straw with seeds in them, wet them & they sprout really well. You can cover them with clear plastic for warmth if needed but not so long as to mold -- maybe at night. Anyway it's also good in summer for those who have to keep their flock penned due to predators. No fuss fresh grass.
If you don't have leaves, etc., for mulches, put a couple large stepping stones or logs, etc. out and move them around once in a while.....bugs a plenty there.
And while we may not be able to raise "all" needed for a winter feed, surely what we can will help. Like others, I raised sunflowers, some milo (will volunteer from scratch if they miss the grain when fed), radishes, kale. Used a "deer feed plot" bag of see for some great clovers, Australian peas, etc. Everyone loved it -- chickens, goats, mini horses. LOL Plan to expand that this year. I also use a good amount of vetch -- good proteins. I make and freeze goat cheeses, thaw in winter and feed chickens.
We CAN feed a good amount naturally and home grown/made.
Too many! LOL But, I actually purchased some of the deer food plot seeds from TSC when it was on sale at end of hunting season here, so February "ish"....and broadcast it onto some freshly roughed up areas &/or bare & raked lightly in some of my smaller pastures (1 acre) & in a more lightly tilled 1/3 ac area I was going to use for this purpose & then graze goats, range layer hens as the area needed (this will be an expanded effort now--blocked sections do well). In pastures, I ran goats &/or minis. Of course, I let it come up first and in the small section by coop I had the sunflowers, comfrey, kales, radishes, etc. This was easy to hand cut with a long blade knife or scissors. Then throw to birds, goats. The Australian peas are still re-growing in the one pasture I tested when I cut it a couple days ago.
So, I have now purchased a couple more bags & intend to sow more this month. I live in Eastern VA, close to NC line, so my weather is good for winter grasses, etc. for another month or so and germination is normally good. I'll also throw out some winter wheat, which will be grazed and not head up, then will die out in Spring. It's an hr or so every couple days for the horses, to give them something green.
The concentration in the small area was amazingly productive and while there was only a small area of the milo, it just forms a tassle head at the top, which can be cut and tossed in a bucket to dry and use. I look for what can be easily hand harvested. Once heads are cut the goats love the leaves. It looks like corn coming up but get about 3' then heads. plants close together and 1/4 acre could be very helpful for feed. Small flock you could feed with the various milo, dried corn, etc.