Vitamin Deficiency in Chickens

In practical terms, identifying any single nutrient as the cause of a particular deficiency is difficult because most nutrients have multiple functions, many nutrients interact with one another in complex ways, and most signs of a deficiency apply to more than one nutrient.

Further, a deficiency may not result from a lack of nutrients in the diet, but from a bird’s inability to metabolize existing nutrients; for example, because an intestinal disease is inhibiting nutrient absorption.

Most signs of vitamin deficiencies show up gradually over time. Unfortunately, by the time particular symptoms show up, it could be too late to improve the diet and make up for the deficit.

These are the 3 primary states of this progression:


  • Lack of energy
  • Loss of appetite
  • Weight loss in adult chickens
  • Reduced weight gain in chicks
  • Egg-production slows down
  • Unkept feathers
  • Eggs with a low hatchability


  • Chickens become disabled
  • Egg-production stops

Severe: Death

Vitamin A

Chickens that are fed stale commercial chicken feed or an incorrectly balanced homemade chicken feed without having access to a green pasture can suffer from a vitamin A deficiency.

Any medical problem, such as coccidiosis or worms, that prevents the body from absorbing nutrients may also be to blame.

Additionally, this kind of deficit makes chickens more vulnerable to coccidia and other intestinal parasites.

Signs of vitamin A deficiency include:

  • Chickens are thin or weak
  • Minimal growth in chicks
  • Poor vision
  • Reduced egg production
  • Eggs with a low hatchability
  • Increased blood spots in eggs
  • Respiratory distress


  • A lot of vitamin A can be found in green grass.
  • Another good source for confined chickens is cod liver oil, which can be added to the feed at a rate of 2 tbsp per 5 pounds lbs when used carefully.
  • A vitamin AD&E supplement, given as recommended on the label, is another excellent source of vitamin A.

Caution: When giving vitamin A supplements to your chickens, use caution not to overdo it. First, it can make eggs taste fishy.

Second, chickens can be poisoned by excess vitamin A. Ironically, the symptoms of excess vitamin A are the same as those of vitamin A deficiency.

Vitamin B

Vitamin B is a group of 8 water-soluble vitamins that play an important role in cell metabolism.

It’s found naturally in some foods, but it can also be taken as a dietary supplement.

Vitamin B helps the body produce energy from food, and it’s essential for healthy skin, feathers, eyes, claws, beaks, the liver, the brain, and the nervous system.

Vitamin B1 (Thiamin)

Signs of vitamin B1 deficiency include:

  • Nerve inflammation
  • Inability to eat
  • Death

Treatment: Legumes, sesame seeds, sunflower seeds, wheat bran

Vitamin B2 (Riboflavin)

Signs of vitamin B2 deficiency include:

  • Eating healthily yet still looking thin
  • Diarrhea
  • Curled-toe paralysis
  • Leg paralysis
  • Death


  • Soybeans
  • Milk products
  • Sesame seeds
  • Whole grains
  • Wheat germ

Vitamin B3 (Niacin)

Signs of vitamin B3 deficiency include:

  • Swollen hocks (the join in a chicken’s hind leg)
  • Bow legs (the legs curve outward at the knees)

Treatment: Fish meal, sunflower seeds

Vitamin B5 (Pantothenic Acid)

Signs of vitamin B5 deficiency include:

  • Foot and facial sores
  • Broken, rough feathers
  • Death


  • Sunflower seeds
  • Corn
  • Legumes
  • Wheat bran
  • Sweet potatoes
  • Whey

Vitamin B6 (Pyridoxine)

Signs of vitamin B6 deficiency include:

  • Weakened muscles
  • Death


  • Milk
  • Legumes
  • Sunflower seeds
  • Wheat germ

Vitamin B7 (Biotin)

Signs of vitamin B7 deficiency include:

  • Foot and facial sores
  • Slipped tendon


  • Legumes
  • Oats
  • Brewer’s yeast
  • Wheat germ

Vitamin B9 (Folate or Folic Acid)

Signs of vitamin B9 deficiency include:

  • Anemia
  • Slow growth
  • Incomplete feathering


  • Leafy dark greens
  • Milk
  • Legumes
  • Whole grains
  • Root vegetables
  • Wheat germ

Vitamin B12 (Cobalamin)

Signs of vitamin B12 deficiency include:

  • Slow growth
  • Small eggs with a low hatchability
  • Death


  • Milk
  • Fish meal

Vitamin D

To build strong bones, beaks, claws, and eggshells, vitamin D is required for the absorption of calcium.

Signs of vitamin D deficiency include:

  • Can cause rickets in young chickens (beak, claws, and keel will soften, may get deformities of the ribs and spine, bow legs)
  • Leg Weakness
  • Small, thin, soft-shell eggs
  • Eggs with a low hatchability

A pattern of normal egg production followed by the appearance of thin and soft-shelled eggs, followed by a decline in laying eggs, followed by a return to normal egg production is a classic indicator of vitamin D deficiency in chickens.

Before she lays an egg, a deficient hen could sit like a penguin due to weak legs.

Vitamin D requirements for chickens are closely related to calcium and phosphorus requirements. Any one of these 3 dietary deficiencies can result in egg eating as well as osteoporosis in older chickens.


  • A vitamin D deficiency can be corrected easily with access to sunlight.
  • Another good source for confined chickens is cod liver oil, which can be added to the feed at a rate of 2 tbsp per 5 pounds lbs when used carefully.
  • A vitamin AD&E supplement, given as recommended on the label, is another excellent source of vitamin A.
  • Full-spectrum fluorescent lighting for a portion of the day is the next best thing when growing chicks cannot have access to unfiltered sunlight.

Caution:Hypercalcemia, or an excess of calcium in the blood, can result from getting too much vitamin D.

In addition to harming the liver and other organs, too much calcium can cause the kidneys to calcify.

Calcium pimples on eggshells, which can be scraped off to reveal tiny holes in the shell, are one symptom of a hen’s diet being excessively high in vitamin D.

Vitamin E

The immune and reproductive systems require vitamin E in in order to function normally.

The most common cause of a vitamin E deficiency is feeding oil-rich chicken feed that has gone rancid, which can happen quickly in warm, humid environments.

Signs of vitamin E deficiency include:

  • Encephalomalacia (the softening or loss of brain tissue)
  • Decreased fertility in cocks
  • Eggs with a low hatchability
  • Potential encephalomalacia in chicks (a lethal nervous disorder that destroys the brain)

A vitamin E deficit in adult chickens does not exhibit any visible symptoms.


  • A vitamin AD&E supplement, given as recommended on the label, is another excellent source of vitamin A.
  • Cod liver oil
  • Soybean oil
  • Corn oil
  • Wheat germ oil

Please Note:The trace mineral selenium and vitamin E go hand in hand.

Lack of either vitamin can cause fluid to build up under the skin, a condition that is easily remedied (exudative diathesis). To avoid this, a sufficient amount of vitamin E in the diet allows the metabolism of enough selenium.

Vitamin K

Normal blood clotting requires vitamin K.

Signs of vitamin K deficiency include:

  • A lot of external or internal bleeding from a minor injury
  • Deaths of embryos during incubation that are very bloody

Treatment: Leafy dark greens and alfalfa are both excellent sources of vitamin K.