In fowls, vitamin D is responsible for normal growth, egg production, shell quality, and reproduction. Vitamin D 3 (1,25dihydroxycholecalciferol) is involved in Ca and P absorption in the gut, bone mineralization (bone formation) and demineralization (bone mobilization); Ca and phosphate reabsorption by the kidneys.
Commercial layers are usually maintained indoors, and do not receive enough sunlight to convert 7-dihydrocholesterolin sufficient levels to supply their vitamin D 3 requirements. This is why vitamin D is routinely added to layer feeds, which is essential for the maintenance of egg production, eggshell formation, and calcium homeostasis.
Deficiency Diseases of Vitamin D in Birds
The two most prominent forms of vitamin D are ergocalciferol (vitamin D 2 ) and cholecalciferol (vitamin D 3 ). Vitamin D 3 is an important nutrient for chickens, especially for growing chicks and laying hens.
The inadequacy of vitamin D in birds results in rickets, retarded growth, soft and rubbery beak, hypocalcemia, parathyroid hyperplasia, elevated serum alkaline phosphatase, a marked expansion of epiphyseal growth plates including cartilage hypertrophy, failure of calcification of cartilage and osteoid, and fibrous osteodystrophy.
In hens, a vitamin D deficiency adversely affects egg production and causes calcium deficiency. The need for vitamin D depends to a large extent on the ratio of calcium to phosphorus. The vitamin D needs of poultry are increased several folds by inadequate levels of calcium and (or) phosphorus or by improper ratios of these minerals in the diet.
Vitamin D Metabolism in the Body
Cholecalciferol (D 3 ) 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)D 3 ). 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 D 3 ). Vitamin D has been shown to stimulate the synthesis of a calcium binding protein in the intestine.
It is an extract of Solanum plant species (Natural absorbance enhancers). It
increases the absorption efficiency of liposoluble vitamin D 3 present in the feed of birds. It maintains homeostasis of Ca:P in body, improves bone density, increases egg shell thickness and vitamin D levels of eggs.
Layers – 250-500 g/tonne of feed
Broiler – 250-500 g/tonne of feed
Breeder – 500 g/tonne of feed OR as directed by Veterinarian/Nutritionist