When people talk about grain fed, I think they really mean corn fed. There is a difference in grass fed vs corn fed. Corn fed is actually less healthy for the cow because they are not supposed to eat corn, they can have bacteria in their body and that bacteria gets on the meat during slaughter/butchering. This is why some livestock gets antibiotics, to counteract the bacteria. So they say grass fed is better, but there is a change in the way fat is stored / distributed in the body when they eat corn vs grass, and this has an impact on how the food tastes / the cut of meat.