Been there. Had a canopy smashed and a parachute (used as a
wing tip weight pulled) while I was in the pub waiting for crew.

No, I didn't abandon the glider when there were cows in the field,
or even the next field, it's just that all the gates were open. Lesson
learned.......

You can chase cows away from a glider by just waving your arms
and running at them, but the problem is they can approach from all
sides. It's also clear from the way they react to you they know
you are from the city, and take the p***.

One more tip- when you come to de-rig and have crew available
push the glider into a corner so it's easy to defend, also park the
car where it blocks and distract them. They'll lick the paintwork
and it will smell a bit afterwards but you can clean it up.