With the FDA approval of organic selenium in the recent past there has been a lot of attention devoted to this trace mineral. Selenium is a very interesting nutritional element in that it is a required nutrient as well as being potentially toxic and carcinogenic. It is also the only nutrient whose concentration in the diet is dictated by federal law.

Selenium, as with most other mineral elements, is contained in soils at varying concentrations. Selenium concentration in soils along with soil pH determine plant concentrations. In those parts of the country, and world, that have high soil selenium concentration and soil pH above 7, selenium toxicity problems have been reported. The central plains of the US and Canada are considered high selenium areas. As a matter of fact, selenium toxicity in his horses may have contributed to "Custer's Stand" being his "Last" one. Soils in the Midwest and the eastern and western US and Canada contain selenium at much lower levels and, consequently, plant levels are quite low.

Selenium is a required nutrient due to its role as an antioxidant and involvement in several enzyme systems. The selenium we supplement is incorporated into a number of selenoproteins that have functions throughout the body. When selenium status is adequate some of the benefits that have been reported include reduced incidence of retained placenta, metritis and cystic ovaries, reduced severity and prevalence of clinical mastitis, reduced somatic cell count, improved calf immunity and survival along with several others. This all sounds great! Why not just increase the amounts being fed? One reason is the above mentioned federal law restricting the concentration allowed in the diet. Another issue is the bioavailability of the form of selenium used.

Sodium selenite is the inorganic form of selenium used in supplementation. According to research by Gerloff, as the concentration of sodium selenite is increased in the diet, selenium levels in blood plasma and milk show a corresponding increase, only to a point. As diet concentration is increased above 0.3 ppm/lb of dry matter there is little increase in plasma or milk levels which may indicate that additional selenium absorption is low. The new organic selenium products on the market have demonstrated that they are more bioavailable, and hence more readily absorbed into the body than sodium selenite. The enhanced bioavailability of organic selenium derives from the fact that the selenium is incorporated into a molecule of the amino acid methionine in a fermentation process to make selenium yeast. The resulting yeast contains high concentrations of the amino acid selenomethionine, which is actively absorbed by the animal. Selenomethionine is then incorporated into various proteins within the body which acts as a ready pool of selenium for the body to draw from during times of stress.

The manufacturers of the various organic selenium yeasts have demonstrated that their products have greater bioavailability and have proven they can generate higher blood, milk, and tissue selenium levels with supplementation rates comparable to sodium selenite. These are certainly considerations favorable to use of the organic selenium products. As ANC evaluates possible use of these ingredients in our product line, however, we keep in mind that dairy producers do not get paid any more if their cows have higher blood, milk and tissue selenium levels. The organic selenium products are also more costly than sodium selenite. We also keep in mind that additional ingredient cost must be economically justifiable based on health or product benefits.

The advantages of selenium supplementation noted earlier relate to a relatively short time in the dry period on through to freshening and early lactation. For that reason ANC has chosen to make a change in our DAIRY DC and PREFRESH BASE products, substituting organic selenium in place of sodium selenite. These products are used during the time periods in which most of the problems noted above are likely to occur. Retained placenta, metritis and cystic ovaries are related to freshening problems; the highest incidence of mastitis occurs at dry off and freshening and increased calf immunity due to improved selenium status will be built up late in gestation.

We are still waiting for some good research demonstrating economically significant improvements in performance in lactating cows receiving organic selenium versus sodium selenite. The most typical benefit related in lactating cows is reduction in somatic cell count. High somatic cell count is an economically significant problem in many, but not all, dairy herds. Same is true with mastitis and the other problems noted above. For ANC to make the change from sodium selenite to organic selenium in RATION-ALL BASE or DAIRY BASE we are incurring additional cost for all of our customers.

At this time ANC is staying with sodium selenite as the selenium source in our milking cow products. Our recommendation is to use additional organic selenium in lactating cows in herds experiencing some of the problems noted above rather than increasing the level of sodium selenite. In these cases we recommend adding a source of organic selenium to the grain, protein, or mineral mix. All brands seem to be equally favorable to us at this point.

We will continue to monitor the research on organic selenium. Inclusion of selenium yeast in ANC products for milk cows depends on further research and economic benefits. We strongly encourage all our customers to work closely with your ANC consultant to address the underlying causes for these problems.

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