Vitamin D? Vitamin D is vital for calcium homeostasis in animals and man. A deficiency may lead to bone deformities, commonly called rickets, resulting from decreased concentrations of calcium and phosphorus in cartilage and bone. The vitamin is found as vitamin D2 (Ergocalciferol) in plants and as vitamin D3 (Cholecalciferol) in feeds of animal origin, especially fish. The two forms, D2 and D3 have similar biological activity; 1 µg of D2 or D3 equals 40 international units (IU) vitamin D. During summer, exposure to sunlight leads to production of vitamin…