18 - Vitamin bioavailability

Abstract

The available literature on vitamin bioavailability in feed ingredients is very limited. Crystalline thiamin is available to the food and feed industries as thiamin-HCl (89% thiamin) or thiamin-NO 3 (92% thiamin). Crystalline riboflavin is available for addition to feeds or premixes and is considered quite stable, although it is easily destroyed by UV light when in solution. The term “niacin” is the generic descriptive term for pyridine 3-carboxylic acid and other derivatives delivering nicotinamide activity. This B vitamin consists of pantoic acid joined with B-alanine by an amide bond. It is generally sold in crystalline form as either D- or DL-calcium PA, and only the D-isomer has bioactivity. Plant foodstuffs are devoid of B 12 . Microorganisms are the sole source of B 12 in nature and these account for the B 12 activity in animal and fermentation by-products. In animal nutrition, chlorine remains in the B vitamin category, even though the quantity required far exceeds the “trace organic nutrient” definition of a vitamin. Commercial D-biotin is a sulfur-containing imidazole derivative that has no specific unit of activity. This B vitamin consists of three closely related naturally occurring pyridine derivatives: pyridoxine, pyridoxal, and pyridoxamine. The term “folacin” is the accepted generic term for folic acid and related compounds exhibiting “folacin” activity. Ascorbic acid is a water-soluble vitamin that is oxidized easily in air to dehydroascorbate. Water-soluble forms of menadione are used, primarily, to supplement animal diets. All three forms of vitamin K are biologically active.