Not sure what small tree can handle heavy munching. Maybe willows but they are not small. They grow fast though and can handle lots of abuse. Mullberries perhaps. They also grow fast and provide fruit for animals and humans in spring and summer.

Nut trees like oaks and chestnuts will provide winter feed also but take many years to grow. People are reluctant to plant trees in their pasture for fear of losing grass. That is a mistake. You plant production trees in clusters and leave space in between for pasture. Now you have multilevels of production on the land where you only had one level before.

Animals need diversity especially goats and sheep they will browse but even cows browse. You can seed grass that does well in shade. Also bushes like elderberry for medicine and hazel nuts more winter feed. You have to protrct the young trees though till they get big enough or the animal wil kill them.

My plan is to plant mullberries as they grow fast and provide shade and fruit. While my nut trees are coming up. I planted about 80 trees last year but lost over half due to unusual heat. I did not have drips set up as i thought they would have enough moisture. This year i will set up drips i can charge from the pond with a gas pump. All trees are production. I have oaks, black walnuts (stock can eat them, good winter feed too) american chestnuts, mullberry., sugar maple, black cherry, pinion pine (nuts), native blue elderberry, red elderberry. I'll be adding hazel nuts, almonds, etc. For humans i have apples , cherries, figs, grapes, apricots, and will be adding various others. Although apples are good for stock too.