Vitamin A: Recommended daily allowances 
Min: 2500.00 IU/kg     Recommended: 5000.00 IU/KG*
Vitamin A: 20-100 times required amount
Weight loss
Decreased food intake
Swelling and/or crusting eyelids
Inflammation of the mouth
Inflammation of the nares
Decreased bone strength
Dermatitis
Hepatopathy (excess storage in the liver)
Hemorrhaging

Vitamin D3: Recommended daily allowances
Min: 500.00 IU/kg      Recommended: 1000.00 IU/kg*
Vitamin D3: 4-10 times the required amount
Increased calcium absorption
Increased bone resorption
Hypercalcemia
Decreased PTH
Mineralization of soft tissue
Nephrocalcemia (excess calcium to the kidneys)
Polyuria

Vitamin E: Recommended daily allowances
Min: 15.00 IU/kg       Recommended: 20.00*
Vitamin E:  100 times required
Decreased growth
Anemia
Increased prothrombin time (increased time for blood to coagulate)
Decreased bone mineralization
Decreased liver storage of vitamin A

Vitamin K: Recommended daily allowances
Min: 0.80 ppm     Recommended: 1.00 ppm
Vitamin K: 1000 times required amount
High mortality
Anemia
Hyperbilirubinemia

Niacin: Recommended daily allowances
Min: 40.00 ppm     Recommended: 75.00 ppm
Niacin: 10 times required amount
Flushing – vasodilation
Pruritus
Gastroenteritis

Pyridoxine: Recommended daily allowances
Min: 4.00 ppm       Recommended: 10.00 ppm
Pyridoxine: 50 times the required amount
Decreased egg production
Infertility

Choline Chloride: Recommended daily allowances
Min: 750.00 ppm     Recommended: 1000.00 ppm
Choline Chloride: 2 times required amount
Increased mortality
Decreased use of Vitamin B6

Calcium: Recommended daily allowances
Min: 0.30 %     Recommended: 0.50%*
Calcium: 2.5% in excess of diet
Nephrosis
Visceral gout
Renal gout
Hypercalcemia
Hypophosphotemia
Decreased food intake

Magnesium: Recommended daily allowances
Min: 5000.00 ppm      Recommended: 600.00 ppm
Magnesium: 20 times the required amount
Decreased growth
Decreased egg production
Decreased egg quality

Manganese: Recommended daily allowances
Min: 60.00 ppm     Recommended: 75.00 ppm
Manganese: 20-50 times required amount
Iron deficiency

Selenium: Recommended daily allowances
Min: 0.10 ppm    Recommended: 0.10 ppm
Selenium: 50 times the required amount
Decreased weight gain
Weight loss
100 times required amount
Decreased egg weight
Decreased hatchability
Dermatitis
Severe Excess
Blind staggers
Pulmonary congestion/edema
Liver cirrhosis

Copper: Recommended daily allowances
Min: 6.00 ppm    Recommended: 8.00 ppm
Copper: 50 times required
Decreased growth
Hepatopathy
Accumulates in liver
Death

Zinc: Recommended daily allowances
Min: 40ppm       Recommended: 50 ppm
Zinc: 10-20 times the required amount
Gastroenteritis
Decreased food intake
Anemia
Decreased bone mineralization
Depression

NOTE: * Increased levels are suggested for growth/breeding diets due primarily to the high requirements for adequate chick growth as opposed to increased demands for low-level breeding.*

NOTE: Not included in this list are phosphorus, potassium, sodium, chloride, iron and iodine.  
NOTE: Toxicity unlikely because the following are water soluble nutrients and not stored in the body.
Thiamine (rapidly excreted by kidneys)
Riboflavin (rapidly excreted by kidneys0
Pantothenic acid
Folic Acid
Cyanocobalamin
Vitamin C

Vitamin C:  A healthy bird is able to synthesize (manufacture) its own vitamin C.  When there is hepatic (liver) damage there is a need for increased Vit. C to compensate for the lowered synthesizing of this nutrient in the body.

Vitamin D: Disease that affects the liver and kidneys, the enzymes required to produce the metabolically active form of vitamin D3 are impaired, thus the bird would benefit from FSL (Full Spectrum) therapy.

Vitamin K:  Vitamin K is synthesized from the intestinal flora in the intestinal tract. Antibiotic treatments can interfere with this so it may be necessary to provide vitamin K.

Vitamin B Complex: In the case of a bird that is anorectic may be beneficial to provide additional B vitamins, especially thiamine.  Other water soluble vitamins such as riboflavin, pyndoxine and folic acid are important for protein and energy metabolism, therefore these vitamins have increased importance in a disease state.

Zinc: If the bird is nutrient deficient zinc will improve healing and is an important component in protein synthesis.  

Copper enhances the development of red and white blood cells. Deficiency reduces the maturation of lymphocytes. Magnesium is crucial for lymphocyte growth. Deficiency reduces the levels of immunoglobulin and antibody forming cells and promotes production of free radicals and lipid peroxidation.

Some Common Terms:
Hypovitaminosis means deficiency of one or more essential vitamins.

Hypervitaminosis means a condition produced by ingestion of excessive amounts of vitamins. There are 2 categories of vitamins: 
Fat-soluble vitamins, which are: A, D, E, and K. Fat-soluble vitamins are stored in the body, and build up in the liver and fatty tissues.

In either case this can cause an intense itch under the skin which results in plucking to relieve the itch. Also some foods that have corn can cause allergic reactions that contribute to plucking.  If plucking is around the flank of the bird this could indicate an irritation to the kidneys. 

Water-soluble vitamin/nutrients are: The B family (B1, B2, B3, B5, B6, B12) Biotin, Choline, Folic acid, Insotol, PABA, C, P (bioflavonoids). Water-soluble nutrients are NOT stored in the body. They are excreted daily, thus they need to be constantly replenished during times of stress, molting, etc, and the best way to supplement is with Brewers Yeast.

The labeling can give a clue to distinguish between natural and synthetic forms. If the ingredient is prefixed with a d-, this would be natural. If it is prefixed with either a dl- OR an l- this is a synthetic (chemical) component.EX: d-alpha-tocopherol = natural E dl-alfa-tocopherol = synthetic E

The natural form is identical to what the body makes and what is found in food, thus the body absorbs it better, and it stays in the system longer.