Cows produce milk for the same reason that humans do—to nourish their young—but calves on dairy farms are taken away from their mothers when they are just 1 day old. They are fed milk replacers (including cattle blood) so that their mothers’ milk can be sold to humans.(1,2) Female cows are artificially inseminated shortly after their first birthdays.(3) After giving birth, they lactate for 10 months and are then inseminated again, continuing the cycle. Some spend their entire lives standing on concrete floors; others are confined to massive, crowded lots, where they are forced to live amid their own waste. Cows have a natural lifespan of about 20 years and can produce milk for eight or nine years.(4) However, the stress caused by the conditions on factory farms leads to disease, lameness, and reproductive problems that render cows worthless to the dairy industry by the time that they’re 4 or 5 years old, at which time they are sent to be slaughtered.(5,6) On any given day, there are more than 9 million cows on U.S. dairy farms—about 13 million fewer than there were in 1950. Yet milk production has continued to increase, from 116 billion pounds of milk per year in 1950 to 185 billion pounds in 2007.(7,8) Normally, these animals would produce only enough milk to meet the needs of their calves (around 16 pounds per day), but genetic manipulation—and, in some cases, antibiotics and hormones—is used to cause each cow to produce more than 20,000 pounds of milk each year.(9,10) Cows are also fed unnatural, high-protein diets—which include dead chickens, pigs, and other animals—because their natural diet of grass would not provide the nutrients that they need to produce such massive amounts of milk.