Ah, Ground Unicorn Chow, as we call it at the shelter, since it sure is pricey. But most cats who stay on it usually do very well as long as they're willing to eat it.
I have been "promoted" at the shelter to the Cat Enrichment Team, which means I spend a lot more time with the least social cats in the shelter attempting to convince them that humans are okay creatures and perhaps they'd like to go live with some of them eventually. There is one cat that I've been attempting to work with for a month now that I have never actually seen since someone put his carrier right into the cage and he stays in there if he hears a human coming. For the first two weeks I wasn't sure if there was a cat in there at all. The pace is glacial with a lot of them, but we have seen some good progress with a few in the last week. I've now been hissed at so many times that I think I'm starting to learn how to curse at someone in Feline.