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Vitamin E Deficiency

Avian Encephalomalacia, Crazy Chick Disease, Hypovitaminosis E

Vitamin E is a fat-soluble vitamin and antioxidant. Naturally occurring vitamin E includes eight fat-soluble isoforms: α-, β-, γ-, and δ-tocopherol and α-, β-, γ-, and δ-tocotrienol. Vitamin E has been shown to be essential for integrity and optimum function of reproductive, muscular, circulatory, nervous, and immune systems. Vitamin E is stored throughout all body tissues, with highest storage in the liver. Vitamin E an essential nutrient for chickens of all ages, and its deficiency causes several disorders.
  • Encephalomalacia: Encephalomalacia is a serious disorder that causes permanent tissue damage to the chicken's brain, as a result of localized softening of the cerebral. This form of vitamin E deficiency occurs most often in chickens that are getting fed a diet containing high levels of polyunsaturated fatty acids of the linoleic acid series (such as that found in many cooking oils) and low levels of vitamin E. Dilauryl succinate has also been documented to induce encephalomalacia in chickens.
  • Exudative diathesis (ED): ED occurs as a result of selenium deficiency in chickens, and it primarily affects the capillary walls. Clinical signs observed include greenish-blue discoloration of the skin in localized areas of the chick's body, along with edema and hemorrhages, often resulting in bow-legged posture and pendulous (loosely hanging) crop in the throat latch area.
  • Nutritional muscular dystrophy: Nutritional muscular dystrophy, also known as white muscle disease or nutritional myopathy, is a disease that primarily affects the chicken's striated muscles. It involves progressive weakness and degeneration of the muscles that control movement. Affected chicks are often unable to stand or walk, and are seen on the ground with their legs spread laterally.

Nutritional Recommendations for Vitamin E in Chickens

Vitamin E levels recommended in the Nutrient Requirements of Poultry (NRC, 1994) are extremely low and were determined solely based on enhancing productivity traits of broilers and laying hens, and not in relation to immune enhancement and long term health and well-being. Based on latest research studies, vitamin E requirements recommended for chickens at various stages of growth include:
Vitamin E Recommendations for Chickens
Age/Life StageIU/kg
Newly Hatched Chicks (0 - 10 wks)50-100
Young & Growing (10 - 20 wks)30-35
Laying hens (Actively laying eggs)20-30
Breeders (20 wks & older)*50-100
Broiler/'Meat' Breed Chicks (0-18 wks)80-100
Broiler/'Meat' Breeds* (19 wks & older)100-150
*Includes roosters

Clinical Signs

Muscle spasms
Greenish-blue skin discoloration
Loosely hanging crop
Inability to stand or walk
Bow-legged posture
Outstretched legs
"cycling" with legs
Reduced egg production
Poor egg quality
Reduced fertility


  • History
  • Clinical signs
  • Blood test - Serum Vitamin E levels


Vitamin ESelenium/Vitamin E injections
Supportive care



  • Feed a balanced diet with proper dietary supplements with vitamin E and inorganic selenium.
  • Use only fresh feed that has been stored properly in an air-tight container, and not more than 2 weeks old
  • Don't feed vitamins that have passed their expiration date
  • Provide chickens intended for breeding a breeder feed and/or additional vitamin supplements.


Good if treated during the early stages.

Scientific References

Age Range

Signs tend to develop in young chicks between 2-6 weeks old.

Risk Factors

  • Feeding chicks starter feed that is more than 2 weeks old
  • Improperly storing feed
  • Purchasing poor quality feed
  • Feeding breeding chickens laying hen feed, without providing additional vitamins and minerals needed for breeding
  • Feeding vitamins that are past their expiration date
  • Feeding chicks a diet high in rancid fat
  • Diet lacking antioxidants