An essentially dry powdered preparation containing a calcium source for the prevention and treatment of calcium deficiency conditions in mammals, e.g. dairy cows, is enclosed in a substantially water soluble, dispersible or disintegrable casing mainly composed of a cellulose material such as e.g. paperboard, cardboard, millboard, or pasteboard, or a gelatinized starch material. The calcium source is preferably a mixture of calcium chloride and calcium propionate enclosed in a cylindrical paperboard or cardboard tube or a gelatinized starch shell closed at both ends, which is administered to an animal with a bolus or bullet gun. The administration is safe and clean and the powdered mixture is quickly released in the stomach or rumen without causing erosion, irritation or inflammation of the mucosa.