It's probably reasonably high, anecdotally every time I got out walking in the hills in most parts of the UK there are large numbers of sheep and cattle grazing

It's probably reasonably high, anecdotally every time I got out walking in the hills in most parts of the UK there are large numbers of sheep and cattle grazing on basically unusable wilderness, often which is part of a national park so can't be built on much anyway. They seem to be pretty self sufficient eating grass unless there is a heavy snowfall, which is quite rare in England, farmers would then supplement with feed crops like turnips etc.