In the wild they forage for leaves, inner bark of some trees,fruits, nuts, seeds, tubers & roots, insects and eggs. I don't believe that eating a dry pellet can encompass all of that variety or satisfy that food search need. Greys are flexible and do well on most balanced diets, as with anything you can have a bird that has food sensitivities you may need to avoid. Pellets have found to be the cause of over vitaminization issues such a Kidney damage and neurological symptoms like toe tapping so in my opinion moderation in all things and a great variety of foods is closer to their natural diet in the wild. Fortunately we have much more knowledge easily available to us now with the internet and sites like this sharing what we experience than anyone with parrots has ever had before. So do as much research as you like then feed what works best for your flock and your food stuff availability and keep that mind open to new information as it becomes available. No dog chow is not a substitute for pelleted bird food, the balance of nutrition is all wrong and some ingredients are suspect.