In nature NO herbivores eat grain.
Green material (forages) is extremely high in B vitamins which nutritional researchers have linked to curing everything from insomnia to nervousness to epilepsy.
A few extra dollars spent on protein coming from a regenerative farm contribute to mitigating climate change by drawing carbon out of the atmosphere and putting carbon back in the soil.
Livestock raised on healthy soils and that are managed correctly in fact are more nutrient dense.