I read about it in Mother Earth News and then I asked the attendant at the store and he confirmed it for me. I don't like it either wih is why give them extra vitamins in the fruit and veggies.
Well you don't want to have too big of eggs but some protein won't hurt them. I mix mine with some protein and scratch so they get both.
Plus I give them kitchen veggie and fruit leftovers corn cob and they love it. They give flavorful eggs.