I know nothing about this level of discussion around pet food so I have nothing to add but I'll share a related story about cat food and feline communication.
One of my wife's now deceased cats was on store bought cat food and we decided to upgrade him to a better food as we were told the old may be contributing to his urinary tract infection. The cat went a couple of days without eating a thing. I figured, 'Pfftt, if he gets hungry enough, he will eat it.
On day three, we returned home to work to discover that he had crapped in his food dish. He had never missed his litter box before and it would have been a bit of an effort for him to pull this off as the dish was on a raised wooden platform in the shape of a cat that her brother had made for my wife as a gift. He would have had to maneuver his rear end up onto this platform and ... well, you already know the rest.
People say animals don't truly communicate? I say they do just fine.
