Oh, I wouldn't touch Calf manna with a 10 foot pole, but is it trully contributing to bladder stones?
I did some digging! I love kidneys, so here we go.
(And I stand corrected)
In HUMANS, excess protein is associated with increased urinary calcium excretion. BUT you have increase the protein by ALOT to make a difference. Which is so weird, because if you don't consume enough protein you won't absorb enough calcium - very counterintuitive.
Also, animal protein causes more of an increase in calcium excretion than plant protein does (which it looks like calf-manna is plant proteins).
BUT no one knows how much protein in the diet is required by chinchillas, so honestly who knows if the protein in calf-manna would really cause a problem (it isn't THAT much higher than normal diets).
Also, researchers are thinking that the calcium absorption may not be affected at the intestine level, but that it is being pulled from the bones. So maybe THIS is the real reason to not feed calf manna, IF in fact the protein level is high enough to alter calcium absorption. I'll have to do some more digging.