Even USA herds mostly feed on grass or hay. Animals only go to the feedlots for a few months before slaughter. They do add a lot of mass in that period. Anyway,

Even USA herds mostly feed on grass or hay. Animals only go to the feedlots for a few months before slaughter. They do add a lot of mass in that period. Anyway, beef consumers can certainly vote on this topic. If you prefer the taste or morality of grass-fed beef, it's available for purchase.