Jerry yes trees are likely to play many roles in grazing situations for soil, animals,
water, nutrient cycling and more reasons. Important for animals, reducing frosting of grass, shading and cooling water, etc
In the case of small
land units, agro-forestry cropping and pastures planting trees can make a lot of sense and fall within the holistic context so essential to ensuring all such management is not addressing symptoms and is likely to be truly sustained without any damaging consequences.
Managing larger land units I have never yet found it necessary to plant trees because as we put things right using livestock properly managed everything we find begins growing better - forbs, shrubs, trees and grass. I know a lot of people are planting trees to try to stop desertification but that poses the question why are they not establishing themselves.
Where we could not provide water in very hot climates under trees we reverted to artificial shade - even a thatched roof over the main water trough and that helped animals significantly drinking cooler water.