Does a Calf Need Grain to Survive?

Adult cattle thrive on a diet of grass alone. However, for a variety of reasons, many farmers find it cost effective to feed cows grain as well. Calves are born with only two of their four stomachs fully functional, and a diet that includes some grain, such as corn or oats, may help speed up the development of the rumen, the stomach that digests grass. Calves can survive on only milk and hay, but a small amount of grain may help develop their stomach for its adult function of digesting grass.

  1. Cow Digestion

    • Cows have four stomachs: the rumen, reticulum, omasum and abomasum. At birth, only two are developed and functional. The main stomach at birth is the abomasum, which can digest milk but not fiber, like grass. Like a human stomach, the abomasum uses enzymes to digest food. The rumen is the stomach that digests grass and other fibers. This stomach uses bacteria and a fermentation process to convert food to energy. The stomach begins to develop shortly after birth and must be fully functional before the calf is ready to be weaned.

    Development of the Rumen

    • At birth, the rumen is small and nonfunctional. It begins to develop as the calf eats solid foods in addition to milk, along with plenty of water. Milk bypasses the rumen and goes directly to the abomasum, where it is digested. An adult cow's rumen functions best on a diet of grass. However, according to an article published by Heifer Max, an international farm advisory service, a calf's rumen will develop more efficiently on a diet that includes grains. A study by Penn State University shows that the rumen of a young calf eating some grain is larger than that of a calf eating only water, grass and milk, and it has a darker color, indicating a greater blood flow.

    Weaning

    • If a calf's rumen is underdeveloped at weaning, the calf may begin to lose weight and develop some health problems when it stops drinking milk. This is why it is important to start calves on solid food -- grass or hay and possibly some grain as well -- only a few days after birth. Calves are usually weaned between three and nine months, although some farmers wean as early as six weeks. A calf must consume 1.3 percent to 1.5 percent of its body weight in dry feed to maintain its weight and continue growing without milk, so they cannot be weaned until they are eating significant amounts of solid food.

    Grass-Fed Beef

    • In America, most beef and dairy cattle are fed a diet including significant amounts of corn and other grains, especially when they are weaned and shortly before slaughter. In other countries, notably Argentina, cattle are raised on a diet exclusively of milk, grass and hay. Many small, organic farmers in America are also following this model of raising cattle. However, grass that is too young or too old does not contain the right balance of proteins and fiber to keep cattle healthy. Farmers who raise and finish cattle on grass generally use rotational grazing practices to allow the grass to develop until it contains both protein and fiber.