Vitamin
They are complex organic components that the animal needs in small quantities. Although they are needed in small amounts, they are essential for good health and correct functioning of the animal's body. Each vitamin has a different function.
Vitamins should be supplemented in the diet, because most of them can not be synthesized in the body. Both vitamin deficiency (avitaminosis) and excess (hypervitaminosis) can be pathological.
They are classified by their solubility: B and C are soluble in water and A, D, E and K in lipid.