Staying on the sidetrack, that’s now two animals whose young eat adult feces in order to create a bacteria culture capable of digesting their normal diets: the kangaroo (mentioned by reprise) and the koala (mentioned by Mangetout). Any more? All marsupials, perhaps, or just cute Australian ones?
I know rabbits eat their own feces too, but that may be primarily to reclaim more nutrients on the second pass, rather than to acquire gut bacteria.
Wombats certainly eat adult faeces to acquire gut bacteria. The wildlife rescue services make such a big deal of it that I assumed it applies to all marsupials.