In the last four years, we have gone from 2 fainting goats, to currently 16. I've become a bit of an expert on fencing. The first pen was about 40x100. Now we have five sections varying from 15x30 for kidding to a few acres. All of our fence is the sheep/goat fence from TSC. Round, treated posts at 50' apart and t-stakes between at 10' apart. "H" braces or "L" braces at corners or the beginning/end of rolls (330' rolls). The key to this type of fence is getting it TIGHT. I concrete all of the wood posts to allow me to pull the fence tight. I use a couple 2x4s bolted together to sandwich the fence and pull with a come-a-long attached to a skid steer to get it tight. When the machine starts dragging in the dirt, it's tight. Round posts make wrapping the ends and turning corners easier. I built a 75x200 pig pen with square posts and "field" fence and found it much more difficult to work with. Hog panels are for hogs. You can't follow the contour of the ground with them (if you have any), and the larger squares at the top make it easy for horns to get stuck (our goats are not dis-budded). Build it bigger than you think you need. If you can't do that, consider how you might be able to expand later. Have a place to put a goat by itself if needed. Think about the weather. If you build in the summer, where will the snow drift in winter? Be ready to make changes/improvements. Make it easy for you and comfortable for your animals. It will be worth it in the long run.