Vitamin D's role in livestock health.

Vitamin D's role in livestock health.Vitamin D plays a significant role in bone metabolism, controlling how much calcium and phosphorus are released or absorbed from bones.Vitamin D may be described as the sunlight vitamin because it is formed naturally in the skin of animals exposed to ultraviolet light. In most cases, with enough sunlight, animals can cover their full needs in vitamin D only by biosynthesis. However, this is not always the case because natural biosynthesis is ineffective and variable as it depends on a great number of conditions. It is also a very slow process, which is one of nature’s ways to protect animals living outdoors from vitamin D toxicity. Biosynthesis of vitamin D is greatly dependent on the duration of exposure to sunlight. Its intensity and quality is also very important as is the age of the animal. For example, in northern climates like Germany, during the winter months there is practically no ultraviolet sunlight. This means there is very little if any biosynthesis of vitamin D, and supplementation is required even for animals raised outdoors. In contrast, it is evident that in Spain, for example, there is little need for vitamin D supplementation for animals raised totally outdoors, especially during the summer months of intense sunlight. The picture is quite different for animals raised indoors. Even though some facilities might have windows, these are invariably either too small or too dirty to allow sufficient sunlight to reach all animals housed in the building. This means biosynthesis of vitamin D will be inadequate and highly variable. As such, the feed of all animals raised indoors should always be supplemented with enough vitamin D to fully cover their needs, disregarding natural biosynthesis. This supplementation is usually provided through the vitamin premix. more