For most of human history, cattle, sheep and goats grazed on land that wasn't suitable for ploughing, and in doing so they converted inedible grass into edible meat and milk.

在人类的大部分历史时期，人们在不适合耕种的土地上放牧牛羊，这样它们就把不能食用的草转变成了肉和奶。