We have New Zealand fencing (posts with high-tension wires strung between) on our ranch for a couple reasons. First it is quite cheap compared to woven-wire fences and easy to install. Second, it was recommended to us by a large alpaca ranch. It can be electrified and is quite adequate for animals like alpacas which don't challenge fencing. It does come with a couple risks, however.
First, it is not for horses because they can get tangled in the wires, freak out, and do serious damage to themselves.
Second, alpacas can escape.
We have seen this escape three times, but I am convinced all three were accidental, and none of the alpacas involved actually know what happened. This is what I think has happened: The alpacas love to roll in the dirt (or mud, whatever), and in their vigorous rolling, they get their feet, then their heads outside of the fence so that when they stand, they are on the other side! They always seem as surprised as the rest of us when this happens.
Our biggest alpaca, Cabernet, has done this twice, and both times I'm sure it was accidental. The most recent escape was on SuperBowl Sunday, when Charles, my mother and I went outside during a commercial to put the alpacas to bed quickly. Naturally, that was when we discovered Cabernet on the wrong side of the fence, very much wanting to go into the barn to get her treats. We are fortunate that alpacas are very herd-oriented because I have no idea how long Cabernet had been outside the fence before we found her. If she were a horse, she could have been miles away by the time we noticed.
We finally caught her and put her away after only about ten minutes of chasing. Thank goodness we took the time to halter-train her!
We had heard stories about cria accidentally rolling out of New Zealand fencing, so our maternity pasture has 2x4 woven wire fencing. But we never thought a big alpaca could pull the same stunt!
This probably won't be a problem once we get the fence electrified. I suspect it will only take a couple zaps before all the alpacas avoid the fence completely. But take it from me, New Zealand fencing is not secure for alpacas. They can get out, and I wouldn't put it past a smart one to figure out how to do it if it happens to him once or twice.