All the answers to this have been very interesting, thank you. But may I also say, in my opinion there is no such thing as a "silly question" - if there's something we don't know, there are enough people in this wonderful Forum that one or more of them can provide the answer, and every one of us has had to start out somewhere. I knew nothing at all about piggies when I first adopted mine, and have learned so very much - so ask away, yes, but never consider those questions as silly.