Vitamins are essential organic compounds to promote protein, carbohydrate and fat metabolism, and to maintain healthy, normal growth and reproduction of pigs. Divided into fat-soluble vitamins and water-soluble vitamins. Fat-soluble vitamins include A, D, E and K, while water-soluble vitamins include B vitamins and vitamin C. Lack of vitamins in diet will cause abnormal development, slow growth, weakened disease resistance and decreased reproductive performance of pigs.