Interesting range of comments. I've looked at milling my own feed, have an old relic of a hammer mill that would happy do small batches, but knowing how time consuming and unenviable the task is I've put that plan on hold.
I get a feed wagon to come fortnightly, mix and blow it into a bin/feed trailer. If you were at that level of feed consumption rate and had the facilities to deal with it, this works to reduce costs.
Last winter l out wintered my breedings sows and others on stubble turnips which seemed a positive success. Equally would consider kale