To get extra protein you need to feed high protein foods such as scrambled cooked eggs, washed cottage cheese, meal worms, sunflower seeds, small amount of cat food or shredded cheese (be careful due to the salt content). You could also switch them to a starter or game bird feed, but be sure they have plenty of oyster shell for calcium, as well as grit. If they are pecking each other there may also be some overcrowding or boredom. If that is the case, you could do a search for "chicken toys" or "bored chickens". Do they get to free-range at all? Also, we're assuming these chickens are not new to each other--been together for longer than a month.