just one ofmine has a little bald patch on her nose, presumed she rubbed it on the hay rack, it hasn't got any bigger over the winter, in fact seem to be going.
Electric fence - I run a single wire about 12-18 round the inside of the stock fencing, once they've touched it ( the cry they give out is quite heartbreaking, but at least my girls actually ran back to me,) - they are unlikely to go near it or the stock fence again, well for quite a while anyway.
I wouldn't use electric netting, esp if they have horns.