I can see a puppy tearing up a drywall wall, but chickens??? We moved the flock out to their coop last Saturday and in less than a week, they have put several almost-holes in the drywall, torn the paper off around the bottom, and pecked one real hole of considerable size. Uh...do your chickens love drywall as much as ours?
I knew better than to use drywall but they also love insulation, both foam AND fiberglass. Never let any foam insulation show, they seem to have a fascination for it. They will also pick at and eat pink fiberglass insulation.
When I was very small my parents took a 2 week Spanish immersion course in Mexico city. They rented a very small apartment that had once been used to house chickens. All the plaster was missing from the walls up to about 2 feet. In light of the recent news about Chinese drywall products, I don't think I would use it in any chicken coop. It almost sounds as if they use it to get rid of toxic waste!
Ours don't have access to drywall, but they just love Styrofoam. (Seriously, they'd eat it all the time if they could)