I wish I could help. Mine eats grass, dead bugs, deer poop, sand, rocks...I swear I'm going to need to muzzle him. He also pooped 2 plastic red holly berries that has fallen off my wreath this winter. 

 Luckily he seems to have a cast iron stomach and hasn't gotten sick from it...yet. I have to constantly watch him and pry his mouth open, it's so frustrating. I wish I had an answer