Baby Calves weigh approximately 60 to 100 pounds at birth. Within an hour of being born they are able to stand, walk and nurse. During the first 48 hours of a calf's life it is important that they stay with their mother to receive the rich milk filled with nutrients and antibodies. Calves will drink about one gallon of mile each day, until they are weaned at 6 to 10 months old. At that point they weigh 450 pounds or more.