A good resource for such things is always the state Extension Service agent. Or just hike and look at what the area ranchers do.

Here is a PDF with lots of good info. <https://www.uidaho.edu/~/media/Files/Extension/Beef/Over%20the%20Wire%20Newsletters/June%202011%20cattle%20e-letter.ashx>

Building a perimeter fence on 260 acres is a lot of fence: 40 acres is 1,320 feet on a side (if it is square). So that is a mile of fence. It is also more than 500 t-posts plus wooden corner posts and line posts every 100 feet.

If the springs are your primary concern, focus your energy there.

I suggest exploring electric fence. Solar chargers work great. It is impressive how we'll a 2-wire fence works. Even a 1-wire keeps cows under control. My cows will see a new wire for rotational grazing and immediately turn 90 degrees. The calves only have to touch it once. Installation is work but not nearly as hard as 5-wire barbed.