I was considering a frog pond on the edge of a chicken run.
A light above it to attract insects and algae to feed the frogs. As they matured, roughly half would hop into the gaping maws of ravenous chickens.
Sound worth trying?
Frogs really don't breed quickly enough to produce that many tadpoles for several chickens. As a quicker high-protein chicken feed that does well in ponds, how about propagating duckweed? Unfortunately it won't be self harvesting, and the chickens will have to be taught to eat it, as it won't trigger the same instinct moving insects or frogs do. On the plus side, it can double in mass in under 2 days.
On the other hand, if you want something self-harvesting, what about black soldier fly larvae? If you have a source of manure that doesn't come from the same species you're feeding the larvae to, they will breed fairly quickly.
So I left, I came home, and I ate some pie. And then I read this tiny ad: