Vitamins are required for normal metabolism in physiological functions such as growth, development, maintenance, and reproduction. Some vitamins are produced by the pig in sufficient quantities to meet its needs and others are present in adequate amounts in feed ingredients commonly used in swine diets. However, several vitamins need to be added to swine diets in the form of a vitamin premix to avoid deficiency and obtain optimal performance.
The vitamins regularly added to a swine premix are distinguished based on solubility as fat-soluble and water-soluble vitamins. Vitamins A, D, E, and K are fat-soluble vitamins and are mainly involved in tissue development, calcium and phosphorus metabolism, antioxidant defense, and blood coagulation, respectively. The B-complex vitamins are water-soluble vitamins and are required as co-enzymes in several metabolic processes. The B vitamins most commonly added in swine diets are riboflavin, niacin, pantothenic acid, and vitamin B12. Thiamin is sometimes supplemented, but the amounts in feed ingredients is sufficient to meet the requirements. In addition, folic acid, pyridoxine, choline, and biotin are included in sow diets due to the influence of these vitamins on reproductive performance. Carnitine, a vitamin-like compound involved in energy metabolism, can also be added to sow diets to improve reproduction. The maintenance of vitamin potency in the premix mainly relies on providing reliable vitamin sources and ensuring vitamin stability.