Except that they don't. Again, old school dairy farm experience here. The cows were confined to the barn all winter. When we first let them out in the spring

Except that they don't. Again, old school dairy farm experience here. The cows were confined to the barn all winter. When we first let them out in the spring, they went for a stampede around the field. This was a bit risky, because if a fence wasn't clearly visible enough they might trample it and hurt themselves on the barbed wire. In practice, the stampede only lasted for a few minutes, then they settled down and grazed. And that was that; for the rest of the season even the barely visible temporary electric fences (just wooden poles and a wire) would contain them fine. They would graze under the fence, they knew exactly how far they could go without the wire contacting them and giving them a shock. And they certainly didn't jump over anything.