Margaret A. Wissman, DVM
There is often a lot of talk about vitamins: vitamins added to seeds; vitamins in an extruded pelleted diet; vitamins that can be added to soft food or in the drinking water. But what are vitamins, anyway?
Vitamins are organic substances that are essential in minute quantities for the nutrition of most animals, including birds. They are present in natural foods and sometimes can be produced inside the body by vitamin precursors. Vitamins are involved in the regulation of many metabolic processes that go on inside the body, and can act as coenzymes and precursors of coenzymes, but they do not provide energy or serve as building units. Without vitamins, the body can’t work properly. Deficiencies can cause such varied clinical signs as the inability to clot blood properly, form normal blood cells, grow normal bones or even cause infertility.
Vitamin D is often called the sunshine vitamin, as most animals make vitamin D3 in the skin upon exposure of UVB light. Birds with an uropygial (preen) gland produce vitamin D precursors that are activated when spread on the feathers during preening after being exposed to ultraviolet light. Then when the bird preens again, it ingests the vitamin D3.
Vitamin D is another fat-soluble vitamin. There are two main forms; ergocalciferol (vitamin D2) a plant derivative, and cholecalciferol, vitamin D3, produced by an animal’s body. This vitamin is necessary for proper calcium and phosphorus levels in the body and is also involved in cell production and regulation of the immune system.
Deficiency is often associated with reproductive problems, especially in egg-laying hens, seizures (related to low blood-calcium levels) and muscle weakness, falling off the perch and other neurological signs. Treatment by the use of injections of vitamin D is controversial. Vitamin D3 should always be used, not the plant-derived vitamin D2.
Excerpt from BIRD TALK Magazine, November 2010 issue, with permission from its publisher, I-5 Publishing.
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