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Vitamin A Deficiency

Other Names: Roup, Hypovitaminosis A, Follicular Hypeerkeratosis, Phrynoderma, Squamous Cell Hyperplasia

Vitamin A deficiency is most likely to occur in chickens receiving an improper diet, heavily parasitized, or who are suffering from conditions that interfere with normal digestion. Also, vitamin A requirements are higher for chickens under stressful conditions such as abnormal temperatures or exposure to disease conditions.

Chickens with vitamin A deficiency have an increased risk of getting sick. The two main mechanisms involved in the prevention of disease are the effect of vitamin A on the immune system and on epithelial integrity. Vitamin A deficiency also impairs regeneration of normal mucosal epithelium damaged by infection or inflammation and thus can increase the severity of an infectious episode and/or prolong recovery from that episode.

Vitamin A deficiency presents as a number of different clinical manifestations, ranging from xerophthalmia (dry eye), uropygial gland infection, impaired growth, and increased susceptibility to severe infection. It affects ocular tissue in two ways: by slowing the regeneration of the visual pigments following exposure to bright light and by disrupting epithelial integrity.
Vitamin A nutrient interactions

Nutrition Requirements

Vitamin A Recommendations for Chickens
Age/Life StageIU/kg
Newly Hatched Chicks (0 - 10 wks)12,000-13,000
Young & Growing (10 - 20 wks)10,000-12,000
Laying hens (Actively laying eggs)8,000-12,000
Breeders (20 wks & older)*10,000-15,000
Broiler/'Meat' Breed Chicks (0-18 wks)10,000-12,000
Broiler/'Meat' Breeds* (19 wks & older)12,000-15,000
*Includes roosters

Clinical Signs

Rough, dry skin
Eye inflammation
Ruffled feathers
White-yellowish mouth sores
Pale comb and wattles
Decreased egg production
Blood spots in eggs


  • History
  • Clinical signs
  • Diet ration analysis
  • Histopathology - Presence of squamous metaplasia affecting the cuboidal and columnar epithelia of the mucosal glands of the digestive, respiratory, and urinary tracts and the eye.


Vitamin A20,000-33,000 U/kg IM q7dB Speers
Management changesIncrease access to green forage and scratching soils for insects, many of which contain high amounts of vitamin A. Purchase smaller quantities of feed so that your not feeding stale food to your flock.
Add vitamin A rich foods to rationsVitamin A food sources for chickens
Cod liver oilMixed within feed ration at the rate of 2 tablespoons per 5 lb (65 mL per 5 kg), however used sparingly.



  • Provide flock access to green forage
  • Make sure to properly store poultry feed in an air-tight container, free of moisture and exposure to sunlight.
  • Provide chickens fresh fruits and vegetables daily.

Scientific References

Risk Factors

  • Limited to no access to green forage
  • Feeding chickens poultry feed that has been stored for longer than 3 months.
  • Feeding chickens an improperly balanced home-mixed feed
  • Feeding chickens a seed-based diet.