you might want to check out Sepp holzers recipe for what he called bone sauce.
It is supposed to keep the goats from eating the tree bark, and it is said to last for ever. I dont know if it works personally but sepp holzer seems to know what he is doing.
I found it in an old post here about a year ago and thought I would share it because I have always thought it could be of good use. you might want to give it a shot on any of the trees you want to keep from being eaten. that way you could use selectively cut new growth for fodder, and save the bark of the trees.
heres the original post.
https://permies.com/permaculture-forums/1805_0/permaculture/sepp-holzers-recipe-to-keep-animals-off-of-trees good luck
