Often animals were assumed to be herbivores but the amount of invertebrate protein they were getting was WAAYYY underestimated. Here is an article I wrote about apes a while back...
Thanks everyone for the responses, that's a exactly what I needed to know. I'll definitely look into Flock Raiser, it sounds like what I've been looking for. I can't tell you how great it is to hear this information from people who actually use those types of feed instead of reading facts from textbooks and trying to guess....
Wifezilla, that's very fascinating information about the zoos!