Just to explain a couple things...veterinarians take wayyyy more than one introductory course in animal nutrition. Hell I only have a V.A. degree and I had to take 12 hours in animal nutrition. As far as what the vet said on some foods not having animal by-products (especially prescription foods) a couple things here...1. Prescription foods go by completely different standards anyways so that's not in the gammit here and 2. a lot of these natural and organic foods are sold by vets so remember they have quite a stake in the financial aspect of them. Many of these foods cannot get into mainstream stores therefore they rely on vet offices to be sold at which those vets do profit from. Just something to keep in mind. Let me explain what I mean when I say all foods have animal by-products...
As I said before the USDA sets protein requirements for companion animal foods regardless of being "regular", "natural" or "organic". The USDA states in their guidelines that allowable protein fillers include animal parts from any species of the bovine, goat, swine and poultry families. Most pet food brands use chicken and bovine meat and by-products as they come the cheapest from the rendering plants. What natural and organic food companies do is use animals that are a little more expensive such as turkey. However they still use the by-products of these animals as well. The only difference here is that your dog is eating a turkey beak versus a chicken beak. Another thing to keep in mind is one thing the USDA has screwed up on is labeling laws at the moment. The labeling of foods as "natural" and "organic" are very unregulated. For instance these companies will slip in the word nature versus natural and many customers will never notice it. Fortunately the USDA is working on better regulating the natura and organic food market (which means you might be loosing some of your brands soon). As stated above and as I said earlier dogs are omnivores and do require certain fiber fillers in their food. Feeding a dog a pure meat diet will cause your dogs kidneys to cease function in no time flat. It's good to know what by-products are as well. For instance it might seem gross to us for our dogs to eat cow organs and "goat" testicles but these are actually parts that are more nutritious than what we think of as "meat". I mean is that not why doctors tell pregnant women to eat liver because its one the most nutritious parts of the cow??? It's important not to project our own ideas of what's gross on our animals because in so doing we are denying them what their bodies need. Canine nutritional requirements are very different than human requirements.
As a previous post stated as well I really recommend Purina foods (especially Purina One) due to their nutritional benefits as well as the fact that you won't have to worry about the China/melamine aspect as well.
Sorry if I offended anyone and I guess as Kristy said I should have mentioned my background but I didn't really want to come off bragging especially since I am brand new to the site...I just thought I could be of some assistance in the pet department...
I think I'll stick to aviation stuff now!!