The Roles of Different Vitamins in Poultry Production

Chickens have very low requirements for most vitamins, but since most of them cannot be synthesized in the body or are synthesized only in trace amounts, they must be supplied through the diet. Under normal conditions, the vitamins most prone to deficiency are vitamin A, vitamin D, vitamin B1, vitamin B2, as well as vitamins E and K. Chickens are highly sensitive to vitamin deficiencies. When these vitamins are lacking in the feed, the synthesis of essential enzymes is impaired, normal physiological functions are disrupted, metabolism becomes dysregulated, nutrient absorption declines, health deteriorates rapidly, and a range of diseases may develop, potentially leading to death.

1. Vitamin A

Vitamin A, also known as the “anti‑xerophthalmia vitamin,” serves as a regulatory factor during the differentiation of epithelial and skeletal cells in chickens and is a constituent of the photoreceptor cells (rhodopsin) in the retina. In chicks, vitamin A deficiency leads to reddened eyelids and the formation of a white, curd‑like membrane lining the inner surface of the eyelids; in severe cases, night blindness develops, often accompanied by paralysis. In adult chickens, vitamin A deficiency results in impaired vision, reduced egg production, lower hatchability of hatching eggs, and an increased susceptibility to various infectious diseases. Vitamin A is abundant in green forages and carrots. Chickens can convert carotene into vitamin A and store it in the liver. Prevention and treatment of vitamin A deficiency primarily involve improving the composition of the diet. During winter and spring, when fresh green forage is scarce, chickens should be fed diets rich in carotene, such as carrots and yellow corn; for growing chicks, supplemental doses of vitamin A–rich preparations, such as fish liver oil, may be administered.

II Vitamin B1

Vitamin B1, also known as thiamine, can lead to polyneuritis in chickens when deficient. The primary symptoms include impaired motor coordination, resulting in a staggering gait, circling movements, and paralysis. Feed ingredients such as rice bran, wheat bran, soybeans, and yeast are all rich in vitamin B1.

3. Vitamin B2

Vitamin B2, also known as riboflavin, is found in foods such as millet, soybeans, yeast, green leafy vegetables, hay powder, and fermented feed. When chickens are deficient in vitamin B2, the primary symptoms include skin cracking, peeling, feather loss, reduced egg production, and a marked decline in hatchability; moreover, embryo mortality is highest during the mid‑incubation period. During short‑term germination of cereals—before sprouting—the riboflavin content can increase severalfold, making the feeding of germinated grains the most effective way to supplement riboflavin in poultry diets.

4. Vitamin D

Vitamin D, also known as the “anti‑rickets vitamin,” promotes the absorption of calcium and phosphorus in the intestine, facilitates the conversion of organic phosphorus to inorganic phosphorus in the blood, and enhances the deposition of calcium salts in bone tissue; thus, it is directly involved in bone calcification. Chicken skin contains 7‑dehydrocholesterol, and exposure to sunlight is the simplest way to synthesize vitamin D. When vitamin D is deficient and calcium–phosphorus metabolism is impaired, incomplete bone calcification can lead to nutritional rickets. In affected young chickens, the skeleton—particularly the limbs, vertebrae, and sternum—typically exhibits deformities and a fragile texture. In adult birds, in addition to rickets, neurological dysfunction may also occur; in laying hens, vitamin D deficiency reduces egg production, increases the incidence of soft‑shelled eggs, and deteriorates hatchability, resulting in a marked decline in hatch rates. Therefore, chickens should be given ample access to sunlight, and their diets should be supplemented with calcium‑rich feeds. Calcium‑rich sources include lime, eggshells, and bone meal.

5. Vitamin E

Vitamin E, also known as tocopherol, is widely found in cereals and green forages, with particularly high concentrations in wheat germ. A deficiency of vitamin E can lead to muscle atrophy, disruption of nervous system function, and motor paralysis or ataxia in chickens. Moreover, when such eggs are incubated, the embryo mortality rate is very high. Therefore, in poultry farming, it is important to ensure a balanced diet and avoid feeding a single type of feed.

VI. Vitamin K

Vitamin K, also known as the “coagulation vitamin,” is widely found in green plants. A deficiency of vitamin K disrupts blood clotting in chickens; when injured, they may experience severe hemorrhaging, along with internal bleeding and blood in the feces. In chicks, vitamin K deficiency leads to stunted growth, emaciation, and internal hemorrhages; administration of an appropriate dose of vitamin K can restore health.

7. Bile Salts

A deficiency of choline in the diet can lead to fatty degeneration of the chicken liver and disrupt normal hepatic function and metabolic processes. Legumes, yeast, dairy products, liver, and fish are all rich in choline.

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