Biofeed Technology
health-and-nutrition3

Selenium

Why Selenium is required in the animal diet?
As all livestock the higher animals cannot synthesize selenium, virtually all of it must be obtained from the diet. Grains and feed crops are the main nutritional of selenium. But unfortunately, due to the uneven distribution of selenium on the earth’s crust (selenium constitutes about 0.09ppm of the earth’s crust), the selenium content of most major grains and food crops are highly variable and often exceedingly low. Even if elemental selenium may be adequately present in soils, but factors which include acidic pH, heavy cropping soil leaching, porous and sandy soil texture, incomplete aeration due to water-logging can promote the formation of insoluble complexes of elemental selenium and sodium selenite with iron hydroxide which inhibits uptake by plants.
The Soil selenium level in United States are generally low soil selenium levels and therefore suggests that selenium levels in pastures and grains will also be low.
Forages and crops cultivated east of the Mississippi, in the Gulf State, North Western, North Eastern and the Great Lakes regions are relatively low in selenium content.

Physiological Roles of Selenium in Animal Nutrition:
1- Improves antioxidant status:
Selenium acts as a cellular antioxidant and inhibits the oxidation of lipids. Selenium protects tissues and cell membranes by preventing the formation of free radicals that cause cellular damage. Selenium as a component of the powerful antioxidant enzyme glutathionine peroxidise (GSH-Px, each molecule contains four selenium atoms), acting to destroy harmful hydrogen peroxide in the body and converts it into water before they can attack the cell membrane. The enzyme glutathionine peroxidise regulates biosynthesis of chemical messengers including leukotrienes and prostaglandins involved in the immune response.
Selenium is one of the key antioxidants to fight oxidative stress, which results from the cellular process of converting feed to energy, oxidative stress is prevalent in today’s high producing herds, and is associated with high energy rations, heat-treated feed stuffs and diets high in aflatoxins.
An enhanced antioxidant defense system prevents opportunistic diseases from developing and improves growth performance. 
2- Immune Response:
Improve antioxidant status results in better immune function, increasing immunoglobulins concentrations, reducing oxidative stress and improving antibody titers.
3- Regulates the effects of thyroid hormones:
Selenium plays a vital role in regulating the effects of thyroid hormone on fat metabolism and other related effects on growth development and thermal control. The thyroid hormone iodothyronine 5’-edeiodinase (a seleno-protein) is essential to keep calves warm when born in cold weather as the hormone stimulates heat production in the brown adipose tissues.
4- Reproduction:
Selenium acts as an essential part of biologically active seleno-protin involved in sperm structure. A healthy selenium status will promote reproduction performance, as well as better transfer of selenium to the developing embryo and fetus, which leads to improved disease resistance in early life.

Advantages of L(+)Selenomethionine as a Superior Source of Selenium:
1- Selenium from Bioseleno in the form of L(+)Selenomethionine is exactly the same as those found in all natural foods and feeds consumed by mammals. L(+)Selenomethionine is a molecularly integrated single chemical entity, containing selenium in place of sulfer in the molecule of the essential amino acid methionine. This compound is directly incorporated into the body proteins (muscle tissues, milk and egg) by metabolic pathways similar to those of methionine.
2- Selenomethionine is 100% bioavailable for absorption and does not require digestion process. It is a “ready-to-use” from and is highly retained for a longer period in the animal body.
3- Selenomethionine is not only stable in the intestine environment, but also in the volatile rumen environment. The microbes in the rumen will convert the inorganic selenium salt back to elemental selenium and when excreted it causes pollution to the environment. The selenomethionine is protected from reduction and antagonism during digestion for both monogastric and ruminant animals.
4- Retention of selenomethionine in animal tissues is longer than any other seleno-amino acids like selenocysteine or selenomethylcysteine. In times of oxidative stress, the stored selenium in selenometheionine can be degraded rapidly providing fast synthesis of the selenium –dependant glutathionine peroxidise. This enzyme is pivotal in maintaining selenium homeostasis and many antioxidant metabolism.

The Disadvantages of Inorganic Selenium e.g. sodium selenite and sodium selenate as sources of selenium.
• Unnatural nutritional forms of selenium, less absorbed, poorly retained, less metabolized and toxic.
• Inorganic selenium absorption is via simple diffusion, while selenomethionine absorption occurs as an active transportation through the amino acid pathways. Poorer absorption means less utilization.
• More antagonisms between minerals and interfere with absorption by forming unavailable complexes.
• Pro-oxidant properties lower animal performance.