Feeds and Ingredients

Posted in: Feeds and Ingredients
Selenium and Vitamin E
By Ron Meyer, Senior Ration Analyst
Feb 23, 2009 - 6:11:14 PM

Ron Meyer, Senior Ration Analyst

The role of selenium in animal nutrition has changed dramatically. Sixty years ago it was considered a toxic element, causing lameness and death in grazing animals in certain parts of the Great Plains. Since then, selenium has been determined to be an essential nutrient for nearly all classes of livestock.

Many of the functions of selenium in the body can also be covered by vitamin E. Because of the close relationship between these two nutrients, they are often discussed together. One of the chief functions of both selenium and vitamin E is that of an antioxidant. They serve to protect the integrity of cell walls from the harmful and destructive effects of free radicals, which are produced during energy metabolism. This is crucial for the proper functioning of healthy epithelial tissue, such as the reproductive tract and mammary system.

Selenium and vitamin E are also very important in the functioning of the immune system. Symptoms of selenium and vitamin E deficiency include: white muscle disease (muscular dystrophy) in calves, lambs, and piglets; mulberry heart disease in pigs; retained placenta and slower uterine involution after calving in cattle; poor semen quality; oxidized flavor in milk; and poor growth rates. Many studies have been done over the years to demonstrate the effect of selenium and vitamin E in reducing the incidence of retained placenta in dairy herds. More recently, there has been an increase in interest in the role of vitamin E and selenium in reducing clinical and sub-clinical mastitis. One study showed a 30% reduction in clinical mastitis when 1000 International Units (IU) of vitamin E were supplemented daily during the dry period.

Another study indicated that vitamin E and selenium supplementation reduced the number of cows with somatic cell counts over 200,000 by 70%. These studies have led to the recommendation of adding 1000 IU's of vitamin E per head per day during the dry period, 500-1000 IU's during lactation, and 0.3 ppm selenium to the diet at all times. The addition of selenium to livestock feeds is strictly regulated by the Food and Drug Administration, and 0.3 ppm is the maximum amount allowed.

Feedstuffs are highly variable in their selenium content. Feeds that are relatively high in natural selenium are brewer’s grains and linseed meal. Crops grown in parts of the western U.S. can be high in natural selenium, while crops grown in the central and eastern U.S. are normally low in selenium. This makes it very important to supplement rations with selenium. The ANC nutrition program provides selenium to meet the maximum allowable recommendation. Fresh, green forages generally are good sources of natural vitamin E. But as soon as they are cut and stored, the vitamin content drops rapidly, so that hays and silages can be low in vitamin E content.

It is important to supply all of the recommended vitamin E from supplemental sources when feeding stored forages, as the naturally occurring vitamin E can be extremely variable and quite low. The natural form of vitamin E is very unstable, whereas the synthetically produced vitamin E is not. Companies advertising the use of natural vitamin E do so more for sales and marketing, and may not be doing their customers a favor.

The ANC dry cow program supplies 1000 IU's of supplemental vitamin E per head per day. Prefresh rations are set to include 1250 IU's of vitamin E. The ANC program for lactating cows supplies 600 IU's of vitamin E to cows averaging 60 pounds of milk and up to 1000 IU's or more to high producing cows. Most high producing herds on our program include over 1000 IU's of vitamin E to milking cows.

Selenium supplementation as a feed ingredient is in the form of sodium selenite. For on the farm use, this is purchased as premixes that contain either 0.02% selenium or 0.06% selenium. ANC uses much more concentrated forms (1%) in the manufacturing of our vitamin and trace mineral products.

The availability of this selenium as sodium selenite is very good. Organic selenium sources (chelates, proteinates) have been available overseas for years, but have only recently been FDA approved for use in the U.S. At this time their use is very questionable, and our suppliers have not recommended blanket inclusions into our products. This consideration is not made on cost (cost is quite high), but more on its performance in dairy cattle. There may be more research in the future that proves or disproves the use of chelated selenium. Stay tuned for new developments as more research is done!