Overview of Vitamin E Deficiency in Poultry
Three distinct disorders related to or caused by vitamin E deficiency have been recognized in poultry. Each disorder usually occurs alone, although there are occasional overlaps. Deficiency occurs in birds raised in confinement i.e., birds compiled to eat only what is offered to them. Most outbreaks occur in birds fed on rations high in polyunsaturated fats that oxidize and become rancid (6). Some nutritional deficiency is due to hatchability, and some embryonic pathological changes due to deficiency in layer stock.
Role of Vitamin E in Poultry Nutrition
Fats help in the absorption of fat-soluble vitamins A, D, and E. Vitamins may be destroyed due to improper storage, and they get destroyed by oxidation. Vitamin E has antioxidant properties, and it helps preserve other vitamins like A, D, and fatty acids (1). It has a complementary relationship with selenium and cysteine. Vitamin E has preventative effects against the degenerative changes of muscles and exudative diathesis. Vitamin E deficiency in hens causes embryo mortality on the 4th day of incubation due to defective blood vessel formation. Symptoms in the vitamin E-deficient embryo include cloudy spots in the eyes, blindness, abnormal vascular system, hemorrhages, and stunting (2).
Vitamin E protects unsaturated fatty acids, essential fatty acids, and vitamins. Diets with high levels of unstabilized polyunsaturated fatty acids become depleted of vitamin E. Excess of vitamin E in diet interferes with vitamin A absorption and metabolism. Giving vitamin E after vaccination increases the antibody titers (1). Moderate deficiency of vitamin E impacts the reproductive i.e., decreased fertility of males and egg production in hen and immunology processes. Low levels of dietary selenium and vice versa exacerbate vitamin E deficiency. Meat and eggs from vitamin E deficiency birds have increased susceptibility to oxidative rancidity during processing and storage (5).
Etiology of Vitamin E Deficiency
Vitamin E and the selenium-containing enzyme glutathione peroxidase prevent cell membrane destruction caused by peroxides and other powerful oxidants produced as metabolic by-products. There is evidence that vitamin E, selenium, and sulfur-containing amino acids perform separate functions but still act together to prevent the accumulation of harmful peroxides in tissue. Peroxides are derived, in part, from polyunsaturated acids in feeds (6).
The following facts are of interest in considering etiology:
- Encephalomalacia
- Exudative diathesis
- Muscular dystrophy
Disorders Caused by Vitamin E Deficiency
1. Avian encephalomalacia
The disease is commonly seen in 2 to 6-week-old birds. It is a nervous syndrome characterized by ataxia, sudden prostration with legs outstretched and toe flexed, lack of coordination in movement, disequilibrium, lateral twisting of the head with paralysis, and falling on the back (3).
Symptoms
- Affected birds push their head beneath its breast
- Paralysis of the legs
- Degenerative changes in the germinal epithelium of the testes
2. Exudative diathesis
Under this condition, edema of the subcutaneous tissue which later turns green due to the lysis of blood. Birds develop moderate anemia and hemorrhages in the breast, thigh, intestines, and gizzard. The lesions may be seen in association with muscular degeneration. The chicks stand with legs apart (2). Edematous subcutaneous tissue contains hyaline vascular lesions and hemorrhages. In laying hens, the thigh muscle is more susceptible to deficiency lesions than the breast muscle and shows degenerative muscle fibers, including calcium deposits, vascular lesions, and hemorrhages. Distension of the pericardium and sudden death have been noted. Vitamin E deficiency in the presence of adequate dietary selenium does not result in severe signs of exudative diathesis (5).
3. Muscular dystrophy
When a sulfur amino acid deficiency accompanies vitamin E deficiency, chicks show signs of nutritional myopathy, particularly of the breast muscle. The disease is common in 4 and 8-week-old birds. White, necrotic areas of muscle are seen in the breast muscle with white streaks in normal-colored muscle. The condition affects all body muscles, including the gizzard and heart muscle.
Histopathological lesions include:
- Hyaline degeneration
- Mitochondrion undergoes swelling, coalesces, and forms intracytoplasmic globules.
- Muscle fibers and disrupted transversely
- Demyelination
- Neuronal degeneration
- Marked hyperemia of meningeal
- Cerebral and cerebellar vessels associated with ischemic necrosis (4).
Necropsy
- Softening and swelling of the cerebellum
- Hemorrhages are seen in the cerebellum and medulla oblongata
- Necrosis and edema with hemorrhages at the periphery
Recommended level of vitamin E (3)
- Chicks, growers, and hen 10-15 IU
- Turkeys all age 10 IU
The requirements of vitamin E will vary depending on the type and level of fat in the diet and the level of selenium (3).
Control and Prevention of Vitamin E Deficiency
- Mix new batches of feed at frequent intervals. Use only high-quality ingredients. Avoid storing mixed feeds for periods longer than 4 weeks. If prolonged storage is necessary, add chemical antioxidants.
- Use only stabilized fats in the feed.
- Store feeds in a cool, dry place to reduce vitamin and other quality losses.
- Avoid improperly compounded rations.
Treatment for Vitamin E Deficiency
Recommended vitamin E levels are 30 to 150 mg/kg in the diet. Be sure an antioxidant (0,25kg of BHT or santoquin per 1000kg of feed) is in the feed if storage is long or environmental temperatures high. However, the newest forms of vitamins are enveloped, hence more resistant to heat treatments, humidity, and storage. A dose of 0.3 ppm of selenium is recommended in broiler chicken and turkey diets. Zero to 3-week-old chicks and 0 to 6-week-old turkeys should receive half of this selenium in an organic form, which is more readily available to the bird (6).
References
- Poultry international 1999 (38-46)
- H V S Chauhan Poultry diseases, diagnosis and treatment 4th edition 9:179-181
- Ravindra N. sharma avian pathology 6:245-247
- Cheryl B. Greenancre, backyard poultry medicine and surgery 2nd edition 234:256-257
- David E. Swayne diseases of poultry 14th edition 29:1266-1267
- M. Boulianne Avian disease manual 7th edition 179:185-186
- diseases of poultry colour atlas (161)
- Avian Disease Manual 7th Edition.