This does look like deer damage back from autumn when bucks were rubbing antlers on young trees, but nothing can be done to remedy such damage once it occurs. No coating on the exposed wood should be used, and whether or not the tree seals-over the wound only time will tell. If too much cambium (the live sapwood just under bark) was damaged, the part of the tree's canopy that tissue fed may die. For future plantings, trunks can be protected until the tree gets older with a barrier to antler rubbing (anything sturdy that allows for airflow and expansion of the trunk as the wood thickens with age...several materials are sold as trunk guards).

If trees have enough root energy stores and a main trunk has been too badly damaged and dies back, the tree may produce suckers (new sprouts) arising from the trunk base or root system, in which case they can be allowed to mature into new trunks, which will regenerate the tree after several years of catch-up growth.

Miri