I have one RIR that consistently lays eggs that have thin shells or at least 1/2 of the shell is thin. I have fed her egg shells in their food and even cooked her eggs filled with oyster shells and fed back to her. This helps some of the times, but she continues to lay eggs with thin shells. Since the egg shells are thin, they get cracked or completely smashed in the nest from other birds going in and setting on it. I can't keep cleaning the nest of egg white and yolk in the straw. She will have to go if I can't get her better. Any suggestions would be greatly appreciated.