content: Logically, it can't possibly be less efficient than the entire life cycle costs of a cow, plus whatever portion of the life cost of its mother (I dunno how many babies can a female cow produce until its spent, so this is a variable, maybe 8 or 12 or 15 or 20) so each kg of beef will be whatever that cow required, plus a percentage of what its mum required as well. Some say it takes 100,000 litres of water per kg of beef. This guy says it takes ZERO -- cause, rain and cows piss on the grass. But even this farmer, who just happens to grow cattle in what must be the perfect spot on Earth for it, admits that this ideal environment doesn't exist everywhere on Earth.