Hard to get past barb when you have cattle 
this. And ditto half-tonne Fell Ponies who love to lean.

I have found a bottom strand of barbed to be a good deterrent to pigs who are just rootling and happen to arrive at the fence line. If they get to the point where they're determined to escape, having eaten everything where they are, then maybe it isn't so good.
The bottom strand of electric only works if you can go round and check it all daily, removing the heaped up earth that pigs make - it is exactly that, an earth, and will render the electrified strand just a plain strand - not much of a deterrent.

Similarly, if the grass - or weeds - grows up and over the wire, then the current is reduced and so is the deterrent effect.