Spirited Away has a bath house full of spirits who serve and feed their spirit visitors. And one of the sources of their food are the pigs they keep in pig pens. We know that those pigs are edible, because Yubaba at some point implies that Chihiro's parents (turned into pigs) may be ready to eat. Moreover, Chihiro's parents are not spirits, and are therefore not spirit pigs. And they are kept in the same place as other more-or-less identical pigs - which makes me suspect that, in that world, pigs are not spirits, but are animals raised for consumption.
My question is: do we know where those pigs come from? Are they pigs that belong only on that world, or is there some basic back-and-forth between the spirit world and ours that results in meat animals making their way there? Has Studio Ghibli ever shed light on what seemingly ordinary pigs are doing in the spirit world? Or does animism have something to do with this?
It may also be that this is just one of those things intentionally given to us as a mystery, to be accepted and not deconstructed. So if there isn't any solid info given to us on this, I would consider that valuable information in itself.