" When we use animals to convert crops into meat, eggs, or milk, the animals use most of the food value to keep warm and develop bones and other parts we can’t eat. Most of the food value of the crops we have grown is wasted—in the case of cattle, we get back only 1 pound of beef for every 13 pounds of grain we feed them. With pigs the ratio is 6 pounds of grain to 1 pound of pork. And even these figures underestimate the waste, because meat has a higher water content than grain.30 The world is not running out of food. The problem is that we—the relatively affluent—have found a way to consume four or five times as much food as would be possible, if we were to eat the crops we grow directly. "

― Peter Singer , The Life You Can Save: How to Do Your Part to End World Poverty