Instead of periodically offering protein sources, I would switch the flock over to something with 18-20% protein like a good chick starter, Flock Raiser or All Flock. Put a couple of container of oyster shell on the side for active layers.
Can you provide pictures of your setup?
Yes, you can correct bad behavior if you address the cause(s).
Lack of protein. What exactly are you feeding them?
Lack of space. How much space do they have in the coop and the run in sq ft? Can you post pictures?
Lack of stimulation. What is in their environment? Again... pictures.
I would...