I'd be curious about your research program. I've been feed large numbers of cats and dogs ordinary Purina dog and cat chow for fifty years and never seen any health problems. I have switched to lamb and rice for the dogs. Consider you and your pets lucky. May I ask how long most of them lived and what they died of? No skin, eye, ear problems? I have spent countless hours researching, reading books, and talking to others. I have also had friends switch their animals from the poorer foods and have witnessed the results.
Most of my pets have lived past 15. I don't count cats that play in traffic. About 20 years ago I lost all my cats to feline lukemia. I don't count that either. The dogs are mostly getting better food now, but the cats still live on Purina.
I agree that cheap beef containing dog foods seem to cause skin problems. I don't know about corn. That's new to me.