So what if they fart? As do all ruminants, they produce methane, which adds to greenhouse gases. But consider -- if grasslands are not grazed, there will be vast prairie fires, like those after the buffalo herds were killed off. You may ban feedlots; please do. Instead, crossbreed cattle with buffalo and steak can be fattened on grass alone. As for dairy cattle, methane can be lessened by feeding seaweed, and manure can have methane removed to use for fuel while the remainder is fertilizer.