Why 'Grass/Forage' and not just 'Grass'?
We add the term 'forage' finished instead of just using 'grass' finished. They both mean approximately the same thing, but when some say 'grass', they mean 'grass', despite most 'grass finished' animals being fed on a more diverse pasture.
Native prairie grassland ecosystems tend to be about 90% grasses plus a diverse mixture of sedges, legumes, forbes, shrubs and trees. Bison living in this environment will eat around 95% grasses, and 5% all the others.
However, most grasslands ecosystems are mixed ecosystems like the northern Parkland ecosystem we live in. In these systems, grasses are still the primary binder of topsoil, but there is a much higher percentage of the other plant categories. In Parkland regions, for example, Aspen Poplar dominates the wooded areas, with regions of other tree species. When the trees are cleared, the grasses dominate, but with a higher percentage of shrubs, legumes and forbes than in prairie regions.
Our pastures are a mix of tame and native Parkland pasture. Our tame pastures are fairly old and have a fairly high infiltration of native species, particularly shrubs and legumes.
In our environment, we've noticed that Bison will browse (eat from woody species, rather than grazing grasses) much more than in prairie areas.
So, our bison eat 'forage', not just 'grass'. However, it's all natural and they graze or browse it.
Prairie Grassland in summer.
Aspen Parkland in summer.