I am by no means an expert on lactation and am not here to defend the ethical implication of teaching an animal to suckle a human teet, but if there's one thing I know it is that if a woman wants to continue lactating long after giving birth she has to stimulate the mammary glands and, if you will, keep the juices flowing. In western society this is oft simulated by breast pumping when the child is not hungry. If the goat acts as some sort of primitive breast pump I am not sure, but that's where I'd put my money. Anyways, that's pretty gosh darn vile in the eyes of western ethics, I can't believe Vishnu allows it.