Xen- (prefix): Foreign or other. As in: 1  Xenoantigen -- An antigen that is found in more than one species.  Xenograft -- A surgical graft of tissue from one species to an unlike species, genus or family.
Diet. Snow Geese feed almost exclusively on plant material. During the breeding season, they eat many seeds, leaves, and roots of aquatic vegetation. The very young birds feed on invertebrates. Berries become more important in the fall. In winter, waste grain from agricultural fields has become a primary food source.
By the time the birds are 5-6 weeks old, a good share of their feed can be from forage. Geese can be very selective and tend to pick out the palatable forages. They will reject alfalfa and narrow-leaved tough grasses and select more succulent clovers, bluegrass, orchard grass, timothy, and bromegrass.