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Vitamin A Deficiency

Roup, Hypovitaminosis A, Follicular Hypeerkeratosis, Phrynoderma, Squamous Cell Hyperplasia

Vitamin A is a generic term that encompasses a number of related compounds that are essential fat-soluble molecules predominantly stored in the liver. Vitamin A comes from two sources. One group, called retinoids, comes from animal sources and includes retinol. The other group, called carotenoids, comes from plants and includes beta-carotene. Vitamin A is involved in vision, immunity, embryogenesis, maintenance of epithelial cells, growth, reproduction, and membrane integrity. It is important for keeping the eyes, skin and inner linings of the bird's body healthy and resistant to infection.

Vitamin A Deficiency in Chickens

Vitamin A deficiency signs may present as issues with vision, skin dermatitis, reproductive defects, and increased susceptibility to infections. This is because a diet deficient in vitamin A causes disturbances to the protective mucus lining surrounding the outer layers of the chicken's esophagus (throat), oropharynx (oral cavity), paraocular glands (involving the eyes), sinuses (nasal cavity), proventriculus (stomach), and bursa of Fabricius.

Risk Factors for Vitamin A Deficiency

  • Malnourished or starved chickens.
  • Feeding chickens feed which has been stored for longer than 60 days.
  • Lack of access to fresh forage.
  • The chicken has an underlying condition that is causing an impairment in vitamin A absorption or storage.
  • Vitamin imbalances
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

Ruffled feathers
White-yellowish mouth sores
Runny eyes and nose
Eyelids stuck together
Pale comb and wattles
Decreased egg production
Blood spots in eggs
Swollen sinuses
Difficulty breathing
Decreased egg hatchability
Dry, flaky feet


  • 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.


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
  • Throw away any chicken feed that is still present after a month. If needed, purchase in smaller quantities or split feed with another flock owner.
  • Make sure to properly store feed in an air-tight container, free of moisture and exposure to sunlight: This is because vitamin A content is dramatically reduced with contact to ultraviolet light.
  • Feed supplemental A vitamins or Vitamin-A rich food sources

Scientific References


Risk Factors

  • Limited or no access to green forage
  • Chickens that are fed stale commercial feed
  • Improperly balanced home-mixed feed
  • Illness which interferes with absorption of nutrients, such as coccidiosis.
  • Internal parasites
  • Chicks hatched from vitamin A-deficient breeders.