Dairy

One of the main differences between mammals and other living creatures is that mammals produce milk for the sole purpose of nourishing their young. Milk is a nutrient-filled liquid that helps young mammals adapt to life outside the womb. Humans, however, have developed a liking and a dependence on milk that goes beyond infancy, and in many cultures today, milk is considered an essential part of a balanced diet.

The main source of milk for human consumption is the cow. The most common dairy-producing breed in North America is the Holstein, which has been bred specifically for the dairy market. The Holstein reaches maturity earlier than other breeds and has a longer milk-producing life. It also produces more milk in proportion to the amount of food ingested than other breeds. Other common breeds of dairy cows are Jerseys, Guernseys, and Brown Swiss.