If you've ever seen a deer jump a barbwire fence, you'll see it is no problem at all, effortless for a grown deer to jump an average fence. Also be aware that a fence might not be a problem to trespassers too. It can cost alot of time and money to build a good, long lasting fence. Just don't expect to never have another trespasser ever again, becuase it probably wont happen.

Oh- I just read your other post. Do you own this land or lease it or what? If your having that much trouble and you've tried reporting them and putting up signs and what not, and you lease it, I'd find another lease. But, obviously if you own it, you have to pretty much find a way to deal with it. I'd never put up barb wire or spikes to hurt someone, you easily accidently kill someone doing that, trespassing isn't punishable by death. Not to mention, you could have someone get lost (not trespassing, honestly lost) and stumble upon a spike and fall on it or anything, you just don't know.

Well good luck to you and I hope your situation gets better.