From a nutritional perspective, the Vitamin A is one of the most likely of the vitamins which can cause a deficiency in birds in captivity. Vitamin A (retinol) is a fat soluble vitamin, and occurs in small amounts in the diet.
Vitamin A provides good resistance. Many eye problems stem from a lack of vitamin A. In addition, a deficiency can cause a dull plumage.

Vitamin A is important for birds recessive white canaries, blue goulds have added vitamin A needed. Vitamin A is also called the anti-infection vitamin. A deficiency can cause damage to the skin (epithelium), mucous membranes of the beak, pharynx, esophagus and respiratory tract.

Also in rearing by parents is the vitamin A is essential. A cause of death of young after 7 days is often a result of E. coli or a lack of vitamin A. The above symptoms can counteract by structural features of vitamin A. birds

Vitamin A can be mixed either with the feed as well as by the drinking water.
It is advisable to dissolve in 1 liter of water to 1 scoop of vitamin A or by mixing a kilo soft food.