I adhere to the last words uttered by Q to James Bond on screen: "always have an escape plan"
In practice this means sticking close to a wall, fence or river that you can use if you have to. Used to live on a farm and the farmer's advice on being charged was to side-step at the last minute and 'find something sharp and go for the eyes'.
Not sure about this last bit though. Fellrunners seem to divide opinion enough without indulging in a spot of casual bullfighting...
Behaving like a farmer often helps, ie shouting at them to shift and gesturing towards them to show them where you want them. Most important is to be confident, run away from them and they'll follow to see what you're up to (hence the feeling of being chased). In most cases they're more likely to tread on your foot or knock you over by accident whilst being nosy rather than deliberately trample you. Behave like you're the boss and they'll respond accordingly, providing you're not threatening a calf
I once had to lead agroup of ladies on a charity walk along Hadrians Wall when we came to a field full of quite aggressive Highland cattle on the path. I had to exude confidence and keep the group together whilst I was not a little nervous inside...
Another one! This time at our local Farm Shop....
http://www.bbc.co.uk/news/uk-england-leeds-18459937
Working with farmers nowadays I discuss this one quite a bit with them. All farmers I have spoken to say that they wouldn't go into a field of cows without a big stick to control the cows and whack the cows with if need be.
As to the comment about cows not deliberately being agressive that is misleading. Yes a lot dairy cows tend to be just inquisitive because they are used to being handled twice a day but cows with calves and bullocks can and will be be aggressive even if you're doing everything right. The less they are used to being handled the more likely they are to be aggressive. Just showing confidence can be a start but even farmers have their cattle turn on them sometimes. Hence the stick!!
I don't disagree, but I usually find cattle are harmless. Very occasionally you get an aggressive herd or a bull, but generally, being confident and shouting them out of the way will be fine. If they do turn, it's always wise to have a plan b (as in any situation) such as a handy escape route.
I worked for several years in "trauma theatres". In that time I saw 4 cow "incidents". One was a farmer that was in the wrong place when one of his cows decided to back up. The other 3 were all dog walkers that had walked into a field with cows with young. 2 of the 4 sadly, didn't get past resus. I really don't know about the confidence as I don't have any where cows are concerned. I've been know to do a few miles detour rather than go through a cow field (with or without young) if I don't have at least 3 escape options.
Think its safe to say I'm a right scaredy cat.