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Vitamin D Deficiency

Hypovitaminosis D

Vitamin D Deficiency Overview

Vitamin D3 is an important nutrient for chickens, especially for growing chicks and laying hens. In young chicks, a vitamin D deficiency can cause rickets, resulting in leg and beak deformities. In hens, a vitamin D deficiency adversely affects egg production and can cause calcium deficiency.
Vitamin D3
In order for absorption of calcium (Ca) and phosphorus (P), adequate levels of vitamin D3 must be present. Chickens can get vitamin D3 in their bodies through two different routes---by ingestion of it in feed or by exposure to sunlight.

Make sure not to go overboard with the Vitamin D3
When chickens receive too much vitamin D3 it can result in excess calcium in the blood which is referred to medically as hypercalcemia. This is a serious condition which can lead to gout, heart problems, and liver damage. A clinical sign of too much vitamin D3 in the diet of laying hens is the production of eggs with calcium pimples on the eggshells. When the pimples are scraped off they will leave tiny holes in the shell.

Clinical Signs

Penguin-like (weak) stance prior to laying an egg
Decreased egg production
Thin or soft-shelled eggs
Small eggs
Calcium pimples on eggshells
Stunted growth
Softening of beak, feet, and keel
Poor hatchability
Bent or malformation of beak
Bowing of legs


  • History
  • Clinical signs
  • Diet analysis


Increase access to sunlight
Cod liver oilAdd to feed ration at a rate of 2 tablespoons per 5 pounds (65 mL per 5 kg)G Damerow, 2015
For young chicksProvide full-spectrum fluorescent lighting for part of the day


Scientific References

Risk Factors

  • Keeping chickens indoors, with little to minimal access to natural sunlight.
  • Keeping chickens in an outdoor enclosure that doesn't get much sunlight, and is mostly shaded.
  • Egg laying hens