We moved our 20yo+ herd in 1999 from a place that had thin electric fence wire on top of wood fencing. It's probably the only thing worse than barbed wire bc the owner was eratic about the power to it, and one time I came out to find my 30yo horse with fencing wire wrapped around his back pastern!!!=0
We had 4/5 acres in old, properly put up cattle fencing with 2 strands of barbed wire on top. My old herd never got hurt on it. I imagine very young horses might have hurt themselves on it, so I do NOT recommend putting up brand new cattle fencing to enclose your pastures. Now that I've had the new fencing for a few years I STILL find pieces of rusty barbed wire. **sigh**
Where I used to keep my horses was the location of the family dump at one time. I spent all 14 years picking up garbage, putting in my pockets and throwing away in the garbage can I kept out there. I developed an eye for little pieces of glass and pottery. Fortunately there hasn't been much on my new place, which was a farmily farm some 100 years ago.
Personally, IMHO, I really like wood on the top of any fencing. =D