Excisting pasture fence and had surveyed and line is 10ft off border

Their fence is 10' over your property line, and they are the ones with a pasture?
What country, state?
Have you told them yet?
"Good fences make good neighbors."
If you want, you can take it down. But of course that would be foolish, because your neighbor will be upset, and because surveys can be wrong.
So go talk to them!