Whether in its – formulation, purity, stability, bioavailability, reliability, safety or benefits – Selisseo® never compromises to achieve excellence. Make a definitive choice on selenium supplementation for your herd – choose Selisseo® for no compromise on performance!

The importance of selenium supplementation for ruminants

The mineral selenium is essential for a wide range of biological processes in cattle including; growth, milk production, immunity and reproduction. Any deficiency has a negative effect on the health and performance of cows due to a decline in antioxidant defences – often combined with stress. Cows can’t make selenium; it must come from their diet. The form supplemented determines how much selenium is available to act as an antioxidant.

Selisseo® is a 100% pure source of hydroxy-selenomethionine, with a high level of bioavailability, backed up by science.

The effects of stress on cattle

Cattle are subject to a variety of physiological, sanitary, environmental, technological and nutritional stresses. Stress increases free radical production, resulting in oxidative stress. This imbalance damages animals’ tissues, negatively effecting production and reproductive performance. Providing organic selenium to cattle helps build their reserves, so that during periods of stress, they can combat oxidative stress. As well as ensuring the effectiveness of the antioxidant system, it supports immunity and fertility. Adequate selenium status is essential to maintain animal performance.



Antioxidant function of selenium

Without natural antioxidants living organisms would not be able to survive in our oxygen-rich environment. The players in the antioxidant system are fat-soluble antioxidants (e.g. vitamin E), water-soluble antioxidants (e.g. vitamin C), antioxidant enzymes (e.g. GSH-Px) and the thioredoxin system. Together they work as a team to protect the body, with selenium as the chief executive. Selenocysteine is the active form of selenium the body uses to synthesise many important selenoproteins. Glutathione peroxidase (GSH-Px), is an important antioxidant enzyme. Whilst other selenoproteins are responsible for many different physiological and biochemical processes.



The importance of selenium source

Selisseo® is a 100% pure source of hydroxy-selenomethionine (OH-SeMet). SeMet is the natural storage form of selenium that is actively transported through the intestinal membranes. It is incorporated into proteins by the rumen microorganisms, before accumulating in tissues such as the liver and muscle. These selenium reserves are then available to ensure adequate levels in blood, milk and colostrum.


Conversely, inorganic Se is transformed in elemental selenium in the rumen, which is an insoluble form and unavailable to the animal. Experiments have shown that feeding OH-SeMet results in higher levels of selenium in plasma, milk etc.; than sodium selenite. The amount of SeMet in selenium yeasts content is highly variable, from 15 to 70% maximum, which limits their effect on selenium status.



Selenium deficiency

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The level of selenium in soil varies widely between regions. Plants absorb Se from the soil and their ability to do so is dependent on; mineral composition, pH, rainfall etc. If levels in soil are low, levels in plants will also be low – leading to a poorer selenium status in cattle that consume them.

For instance, in Europe there are many regions where the levels of selenium in soil are very low; and sub-optimal levels of selenium in both animals and humans are reported. Higher levels of rainfall and lower soil pH, are predicted due to climate change, increasing the likelihood of poor selenium status in cattle. In dairy cows this would mean:

  • Poor fertility
  • Longer service to calving interval
  • Less transfer of selenium via colostrum to calves
  • Reduced calf growth and health
  • Increased susceptibility to mastitis
  • Higher somatic cell counts
  • Poorer immune status

Selisseo – No compromise on feature


Selisseo® is the only
OH-SeMet on the market.
There are 3 patents on the molecule and its synthesis.


Selisseo contains 100% OH-SeMet – a well-defined molecule.


Selenomethionine is
the natural storage form
of selenium within tissues.



provides 100%
OH-SeMet in every batch.


Selisseo® can withstand extreme feed processing conditions, including high temperatures and pressures.
Selisseo® is stable in premixes, mineral supplements and within the rumen.


Selisseo® has a uniform and dust free consistency, for effective mixing within feed.

Selisseo – No compromise on performance

Supplementation with Selisseo® increases the selenium status of cattle and provides optimal antioxidant protection. This ensures the performance of dairy cows, calves, particularly during times of stress.

Organic selenium supplementation in beef cattle has been shown to improve meat quality. Under challenging conditions, Selisseo® maintains a higher level of both milk yield and quality. With optimum immunity, cattle receiving Selisseo® have lower; metritis, somatic cell counts, incidences of subclinical mastitis; as well as improved fertility. When a cow has greater selenium body reserves, she is be able to pass more on to her calf; both through placental transfer and via milk and colostrum. This improves calves’ immunity, helping them face challenges and supporting growth. Helping all cattle reach their full potential.



Backed up by science

The science starts at manufacture – when a stable, safe, reliable and consistent product is produced. Its ability to improve the health and production of cattle has been demonstrated in over 20 published papers and over 50 scientific communications.

Research has shown that OH-SeMet is highly bioavailable, helping animals fight oxidative stress and supporting performance under challenging conditions.

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