Public radio has run good coverage of grass-fed beef and the farms producing it — worth a listen if you are weighing where your beef comes from.
One figure from that reporting stays with us: by one widely cited estimate, it takes roughly 250 gallons of oil to bring a feedlot animal to slaughter weight. Grass grows on sunlight and rain. Moving cattle from paddock to paddock, and letting the land rest between rotations, is the older arithmetic — and still the better one.