Yes you don't wont to turn your back on them!
I was photographing some plants a couple of years ago while being surrounded by the herd. I happened to put my sunglasses down for a moment to look in the viewfinder, and promply forgot about them. After shooing my way out of the gathered audience, I continued on my way, but a hundred yards away, rememberd I forgot my glasses. I went back only to find them covered in goo after a couple of the cows took an interest in them by mouthing them.....yuk!
Whether they were trying put them on I don't know, but they did seem very cool cows
