Question

Why is it that when a newborn animal is abandoned or orphaned, people will try and find another animal mommy to nurse it? I have seen so many cute photos of animals of different species nursing little babies; the latest being a tiny pig being raised by a dachshund. Companies do make formula for puppies and kittens; why would anyone choose to forgo using them in favor of finding a nursing mother? Could it have anything to do with health? Could it relate to the benefits of feeding from a warm, mammalian mother rather than a rubber and plastic bottle? It strikes me that if a person believes his/her baby pig would be better off being nursed by a dog than fed from a bottle of lab-created formula, we should look more closely at the "choice" between formula and breastmilk in humans. Are we truly telling mothers to use synthetics to fed their infants when we don't even want to use them on our pets?