Vitamin A plays an important role in the protection of the epithelial tissues (including retina and skin) and the mucous membranes and therefore as a protection against general infections.

• Vitamin A plays an important role in the protection of the epithelial tissues (including retina and skin) and the mucous membranes and therefore as a protection against general infections.
• Vitamin D3 takes care of the regular process of the calcium-phosphorous metabolism. It also plays a role in increasing the rate of Ca++- absorption and transport from the intestine and so promoting calcification of bone.
• Vitamin E has an anti-oxidant action.
• This action links vitamin E with vitamin A metabolism (it is used for the stabilizing of vitamin A in foodstuffs), and with the unsaturated fatty acids.
• Vitamin AD3E Oral is indicated for treatment and prevention of deficiencies of the vitamins A, D3 and/or E, in connection with general bacterial infections, improvement of rearing results, growth disturbances, non-infectious reproductive and sight disturbances, enteritis, convalescence and skin problems.
• Prophylactic treatment during strong labour and stressful situations.

Vitamin A

• Vitamin A is necessary for support of growth, health and life of major animal species.
• In the absence of vitamin A, animals will cease to grow and eventually die.
• As a fat-soluble vitamin, vitamin A can be efficiently stored in the liver and yolk of birds, and it plays a role in both the biology of the adult bird and embryo development

Functions of vitamin A:

1. Formation and maintenance of teeth, bones, soft tissue, white blood cells, the immune system and mucus membranes.
2. Retinol not only creates the pigments in the retina of the eye, according to, but also is integral for good vision, especially night vision, and overall eye health.
3. Vitamin A also promotes antibody responses to T-cell–dependent antigens and increases protective antitumor immunity through mechanisms such as induction of cell differentiation and enhancement of migration to lymph nodes.
4. Beta-carotene also acts as an antioxidant, protecting cells from free radical damage.
5. Vitamin A also helps feather grow .
6. Improves egg production and hatchability.

Vitamin D3

• The primary function of vitamin D is to elevate plasma
• calcium and phosphorus to a level that will support normal
• mineralization of bone as well as other body functions.

1. Intestinal effects :

• It is well known that vitamin D stimulates active transport of calcium and phosphorus across intestinal epithelium
• In the intestine, 1,25-(OH)2D promotes synthesis of calbindin (calcium-binding protein) and other proteins and stimulates calcium and phosphorus absorption.
• Calbindin is not present in the intestine of rachitic chicks but appears following vitamin D supplementation.
• Vitamin D has also been reported to influence magnesium (Mg) absorption

2.Kidney effects:

• improving renal reabsorption of calcium.

3.Bone effects:

• The active metabolite, 1,25-(OH)2D, brings about mineralization of the bone matrix.
• During bone formation in young animals, minerals are deposited on the protein matrix.
• This is accompanied by an invasion of blood vessels that gives rise to trabecular bone.
• This process causes bones to elongate.
• During a vitamin D deficiency, this organic matrix fails to mineralize, causing rickets in the young and Osteomalacia in adults.

4.Functions beyond bone mineralization:

• Vitamin D has also been shown to be required for embryonic development of the chick.
• Vitamin D treatment stimulated yolk calcium mobilization and the vitamin D-dependent Ca2+-binding protein, calbindin, is present in the yolk sac
• 1,25-(OH)2D is also essential for the transport of eggshell calcium to the embryo across the chorioallantois membrane.
• The actions of 1,25-(OH)2D involved in regulation of the growth and differentiation of a variety of cell types, including those of hematopoietic and immune systems.

VITAMIN E

• • Vitamin E has been shown to be essential for
  • integrity and optimum function of reproductive,
  • muscular, circulatory, nervous and immune systems .
  • It is well established that some functions of vitamin E, however, can be fulfilled in part or entirely by traces of selenium .

FUNCTIONS OF VITAMIN E:
1.Vitamin E as a Biological Antioxidant:

• the most important functions is its role as an intercellular and intracellular antioxidant.
• Therefore, antioxidants are very important to immune defense and health of humans and animals.
• Vitamin E is part of the body’s intracellular defense against the adverse effects of reactive oxygen and free radicals that initiate oxidation of unsaturated phospholipids.
• Vitamin E functions as a membrane-bound antioxidant, trapping lipid peroxyl free radicals produced from unsaturated fatty acids under conditions of “oxidative stress.”

Mechanism of action:
by neutralizing free radicals and preventing oxidation of lipids within membranes.
So, interrupt production of free radicals at the initial stage.

2.Membrane Structure and Prostaglandin Synthesis

• Alpha-tocopherol may be involved in the formation of structural components of biological membranes, thus exerting a unique influence on architecture of membrane phospholipids
• It is reported that alpha-tocopherol stimulated the incorporation of 14C from linoleic acid into arachidonic acid in fibroblast phospholipids.
• Also, it was found that alpha-tocopherol exerted a pronounced stimulatory influence on formation of prostaglandin E from arachidonic acid.
• vitamin E supplementation of diets increased intracellular kill of Staphylococcus aureus and Escherichia coli by neutrophils.

3.Disease Resistance:

• vitamin E is an essential nutrient for the normal function of the immune system.
• vitamin E and selenium play role in protecting leukocytes and macrophages during phagocytosis, the mechanism whereby animals immunologically kill invading bacteria.
• Both vitamin E and selenium may help these cells survive the toxic products that are produced in order to effectively kill ingested bacteria.
• Macrophages and neutrophils from vitamin E-deficient animals have decreased phagocytic activity.
• The protective effects of vitamin E on animal health may be involved with its role in reduction of glucocorticoids, which are known to be immunosuppressive.

deficiency symptoms

• Vitamin A deficiency symptoms are hyperkeratosis of the skin, xerophthalmia, blindness, nervous symptoms, decreased growth rates and lower fertility.
• Vitamin D3 deficiency symptoms are rickets in young animals and Osteomalacia in adults.
• vitamin E (deficiency symptoms are muscular disorders, e.g. White Muscle Disease, Stiff Lamb Disease).