You get stock fencing that has smaller spaces at the bottom, that graduate up to big ones at the top (hope I've explained that right
) This should be fine for your little pigs, it keeps our Kunekunes in from a week old
You might want to think about putting something on and below your gate though - it's a potential escape route
We run a strand of barbed wire around the bottom of the fence (attach it to your stock fencing or they'll try and squeeze through the gap) but electric would work too
To train the pig to the fence you can either;
1) Hold the piglet and touch it's nose to the wire (you'll get a shock too though
) or,
2) Make a small run of about 6ft x 6ft it will be ample for the first couple of days til they get the hang of it. Make it with solid sides (old pallets', doors, corrugated tin - it's only temporary) line the inside with electric tape around 6 inches up from the ground (maybe lower if your pigs are teeny tiny) and leave them to it, they'll get the idea really quick and
should remember and respect the fence from then on.
HTH
Karen