I don't know whether it is in the countryside code or kennel club guidance but it says not to enter a field of cows before working out how you would get out if they did approach you. Dogs should be on a short lead within the field but to let them go if cattle behave aggressively.
I think all farm animals are clever really. When you see how they behave with their young, it is enough to put you off eating meat really.
Early reading v continental custom - teachers’ thoughts sought




