I have got a small lake but the trough would be very unstable, plus kids are about so that's a no no.
The chick idea is a good one, especially for larger chicks (turkeys etc) that ideally need a bit more room than our brooder offers.
BUT
The tap idea is genious (why didn't I think of that). I want the top at ground level so if I dig the trough into the side of a slope the tap will remain accessable so I can clean it out, and as it's auto fill I can link it up to the well pump so it will never run dry (for those concerned I will put slabs of granite in so frogs etc can get out again if they take a midnight dip).
And I'll use the drained off goo to water the fruit trees so they'll get a feed as well.
Sorted. Cheers for that!