I mark the ones I want to keep for my laying/breeding flock and mark differently the ones I don't want to keep for my laying/breeding flock. For example, after a couple of months, I finally figured out which pullet was consistently laying a thin shelled egg. All the others were laying eggs with nice shells so it was not a calcium feeding problems but probably something genetic with that specific pullet. She was marked for the "Do not let reproduce" group.
For the chicks you saw, my guess is that the blue tag meant, these are the ones I want to sell. Many different things could lead the seller to that decision.
For the chicks you saw, my guess is that the blue tag meant, these are the ones I want to sell. Many different things could lead the seller to that decision.
