That's very interesting, as I have noticed that my guys poo will turn white if left out for a day, sometimes less. I always thought it had to do with the amount of bone (calcium) they had to eat. I learn something new everyday :)
I am sure that there is an element of bone, but from my understanding that is not the main reason why the poops turn white more quickly with raw diets. I don't know how old you are but I remember 40 odd years ago you would see white poops everywhere. A lot of this was due to more people feeding raw meat and bones.
"Bones" I think is the key