I tend to agree with the others - don't risk the nasty bacteria on the maggot thing. Bacteria can overwhelm even a tough digestive system, and what if it gets in their feathers and so on? Then it gets on you from handling them. I've read too many people warn against the maggot thing - though some say it's all right if you don't let the meat get "too rotten" - but that's work and still a risk.
If you're huntin critters - what the other person said might work better: feed that meat directly to the chickens. I'd cook it first (boil it outdoors, I suppose), but that's me. Grinding would be worth looking into.
I've worried about that with worms, too, that they just don't reproduce fast enough (our meal worm "farm" is a pain and not worth the effort). Well, if you had a really good, big compost pile and ignored it a while - you'd have a mess of worms. Just no idea if the work would be worth it as chicken feed.
Minnows reproduce and grow fast in good weather. They need no other predators in their pond. Do you fish? There's meat in fish heads, and if you fillet - there's meat that stays on the bones. Fish guts and even gills have protein. Trash fish that we don't like but that are plentiful - worth considering. Too much of strong, oily fish, they say, puts a bad fish taste in eggs - but a lower amount won't (many commercial chicken formulas have fish meal) - the worst fish tastes isn't caused by fish - it's that gene that some brown egg layers has that causes them to make fishy eggs when fed soy or flax or stuff like that (or so they say).
I'm in So Cal and have had veggie waste on top of my compost pile for months - yet to see one BSF (but haven't checked in a while).
A lot of people I've talked to, especially people from not-so-rich countries, have told me they made their chickens get by on scraps and foraging. They say it worked fine. They never bought chicken feed, ever. It made no sense (or cents)!