Calves are born about once a year. It is very important that they can drink breast milk within the first few hours. This milk is a special, yellow liquid, also called colostrum, which we do not like. Colostrum contains numerous antibodies that protect the calves against diseases. After about five days, the calf has ingested enough colostrum and continues to drink regular cow's milk for another ten months until it can eat grass and other plants.