I have not done chickens, but assuming they work like everything else, then
- they don't need food. Food may heal them if injured (I think it does, but usually if something gets hit its dead so I don't recall). Food lets them breed (here, I guess, lay eggs?)
- you can throw in a stack, they will use it slowly.
- the lox and boar I had ate as much or more often than my character does, so every 10 min or so they would take food. I don't know that they needed this much (again, its required to breed but not to exist).
there may not be any exact timers etc for this. That is the best I can offer.