I can't tell what they are full of, but have pine chips as bedding. I just picked up one of my brahma chicks that will be 2 weeks tomorrow to take pictures for my green chick question. She was very skinny? At first I thought maybe I needed to put a second feeder in,butt have one of those long ones. Then I noticed her crop is full?? Im thinking pine chips? I just don't know? Then I picked up a different one a RIR and she was thin too ? They are same age, what can I do to help. Oh RIR crop was not over full? Im putting clean food in now to see if they eat.