Vitamin D3, Alpha Vitamin for Poultry in its Most Active Form

Vitamin D, also known as calciferol, is the inactive form of vitamin D that can be ingested through diet or be generated endogenously in the skin when exposed to UV light. Vitamin D is converted into its active form 1, 25-dihydroxycholecalciferol (1,25-(OH)2 D3), following a two-step hydroxylation process mediated by two key enzymes, 25-hydroxylase and 1α-hydroxylase. The first hydroxylation occurs in the liver, which converts cholecalciferol at the 25-C position to form 25-hydroxycholecalciferol (25(OH)D). The subsequent hydroxylation of 25-hydroxycholecalciferol occurs at the 1-C position and is mediated by 1α-hydroxylase in the kidneys to produce 1,25-(OH)2 D3, the active form of vitamin D (Alexandra and Barbara, 2013).

Vitamin D is a fat-soluble vitamin essential for the proper metabolism of calcium (Ca) and phosphorus (P), and the maintenance of normal skeletal integrity (Bikle, 1994). Vitamin D also plays a role in Ca and P absorption, regulation of parathyroid hormone, bone mineralization and mobilization, and it controls the incidence of bone disorders (Garcia et al., 2013). In fowls, vitamin D is responsible for normal growth, egg production, shell quality, and reproduction.

Layers are usually maintained indoors, and do not receive enough sunlight to convert 7-dihydrocholesterolin sufficient levels to supply their vitamin D requirements. This is why vitamin D is routinely added to layer feeds, which is essential for the maintenance of egg production, hatchability, eggshell formation, and calcium homeostasis.

Cholecalciferol is the most common form of vitamin D added to feeds. After absorption by the intestinal mucosa, it is transported to the liver, where it is hydroxylated in the position 25, resulting in 25-hydroxycholecalciferol (25(OH) cholecalciferol). This metabolite is directed to the kidneys and hydroxylated at carbon 1, originating the active metabolite of vitamin D, 1,25-dihydroxycholecalciferol (1,25(OH)2 cholecalciferol). Vitamin D has been shown to stimulate the synthesis of a calcium binding protein in the intestine.

It is a blend of Phytoconstituents (Natural absorbance enhancers), contains hydroxylated metabolites of vitamin D₃ (Calcitriol) and some amount of free and conjugated forms as glycosides from plant origin.