If everyone is doing fine, active and acting normal, nothing. You can make sure they're on a balanced diet and watch for any signs of lethargy or laying issues from a specific bird.
You can treat it, hopefully, with amoxicillin but you have to wait for signs of illness so you know who it is.
Provide constant access to their feed and stop all the treats. There's nothing wrong with them except they're spoiled.
Mealworms, seeds, grain, greens, fruit and vegetables are treats, and treats do not make a good diet that they will do well on.
Feed them their formulated feed and only give...
The nitrogen will burn the plants way before you have to worry about any type of 'contamination', chicken poop has to be composted for quite some time since it's so high in nitrogen .
He likely has internal injuries, if he doesn't improve by tomorrow, you'll want to put him down, I'm sorry
https://www.backyardchickens.com/articles/the-chicken-worlds-worst-chore-culling-the-injured-and-sick-babies.72140/
When I hatched silver double laced Barnevelders 2 years ago, I noticed that one of the chicks was noticeably lighter across most of the body, that chick ended up being a male.
Maybe it was just him but I wanted to test to see if there was anything to it.
This year I ordered 2 pullets and 3...