Hello. I have found that there are two 'bites', one for communication and one for defense/attack. If your piggie isn't upset or rumbling or lunging at you but simply nipping you then this is a form of communication as far as the piggie is concerned.
Communication works if the desired outcome happens. If he wanted you to leave his food alone and nipped you to say so and you did leave his food alone - then in his mind the communication worked and a nip from now on means 'get off my food'. Then he nipped you while you were cleaning up poos, was this further 'talking' to you? Did he want you to leave it all alone and did you? If so, then this is now an established way for him to 'talk' to you and you will have to make efforts to show him that it's wrong.
Piggies are sound sensitive, they are also logical. If saying 'no' doesn't work then try doing something he doesn't want every time he nips, so that the nip means the wrong thing. This will confuse him terribly at first - I have seen it in my own pigs - but it will eventually work.
For example, when very small, Columbine started to nip at skin just to communicate...I think she was just saying hello to the big person holding her. So, every time she nipped, she was immediately and with stern words, put straight back in the run - end of cuddle. She stopped nipping.
Second example, Magenta got into the habit of nipping quite hard when she wanted to be put back - because she nipped a couple of times and we did put her back! So we taught her that one. The way to stop her was to simply turn her upside down (carefully) which she didn't like every time she nipped. After a few times, she stopped.
So the only biting I have come across doesn't break the skin, isn't born of fear and is simply a way for my piggies to 'talk' to me and let me know something. You have to train them out of it.
I wish you luck, especially in realising what it is the piggie is saying when they nip!
Sarah x
