Moose are not a grazing animal. Mostly trees and swap foods. I found this below.
In general, preferred trees and shrubs include willows (Salix), trembling aspen (Populus tremuloides), redosier dogwood (Comus stolonifera), red maple (Acer rubrum), striped maple (Acer pennsylvanicum), white birch (Betula papyrifera), beaked hazelnut (Corylus rostrata), pin cherry (Prunus pennsylvanica) and, primarily in winter, balsam fir (Abies balsamea). Aquatic plants, particularly water shield (Brasenia schreberi), yellow pond lily (Nuphar sp.) and pondweed (Potamogeton sp.),constitute a preferred and important part of the moose's diet in summer.