There's nothing special about the diet of these tamed creatures when compared to their wild counterparts. Part of that is the Beast Queen's doing, as she takes them on regular hunting excursions for training purposes.
Curiously, they never have to range too far. There is an abundance of prey nearby, despite the size of her pack. That this has held true regardless of her domesticated creature's remarkable birth and growth rates makes it even more unusual.
Oh, and I did finally get her name - Li Mei-Yin. She's gotten a little less glarey, too. In hindsight, maybe starting by studying her animals' feces just gave her the wrong impression...