Even if you miss the blighters, cattle will also after the initial surprise make every attempt to use your aircraft as a salt-lick and scratching post. If it's fabric covered, you're almost certainly in for some very expensive repairs.
If forced into a field with cattle, either have a couple of people guarding the aircraft, push it immediately out of the field through a gate - anything to keep the sandpaper tongues away from your aeroplane.
Sheep aren't too much of a problem so long as you can find a line between them.
G