Selsaf®: natural source of selenocysteine and selenomethionine to manage oxidative stress in animal production
Modern farming practices, characterized by high stocking densities, highly productive genetics, early weaning and uncontrolled high or low temperatures, impose a cumulative stress on the animal. The resulting high concentrations of oxidative stressors in animal cells can compromise the animal performances with significant economic effects. Supplementing animal feed with organic selenium, containing selenocysteine (SeCys) and selenomethione (SeMet), helps to reduce the negative impact of oxidative stress on animal performance and quality of end-products.
Many stressors, such as heat, diet and transportation can disturb the balance between the pro-oxidant and anti-oxidant systems (Estévez, 2015) (Fig. 1). This phenomenon known as oxidative stress may interfere with physiological processes and eventually causing for example a loss of appetite or muscle degeneration, reducing animal performance. (Lykkesfeldt and Svendsen, 2006).
Today's highly demanding and quality-oriented animal production practices require exogenous supplementation with antioxidants to maintain the balance of the oxidant system and reduce the negative impact of oxidative stress on animal health and end-product quality. Adequate dietary uptake of selenium (Se) is therefore essential.
Selenium plays an essential role for the resistance to oxidative stress on farms. Indeed, the cell defenses are ensured by selenoenzymes, such as the gluthatione peroxydase, whose activities need to increase during stress in order to neutralize free radicals. Within the different available sources of organic selenium, Selsaf®, the premium yeast enriched in selenium, distinguishes itself by its natural origin, its maximum bioavailability, its content with both selenocysteine (SeCys) and selenemethionine (SeMet), and its constant composition.
Selsaf® is obtained from a specific proprietary yeast strain of Saccharomyces cerevisiae, cultivated on medium enriched with sodium selenite which is bio-transformed into organic form by yeast cells. Selsaf® is an excellent source of selenomethionine, which is incorporated in the body proteins (muscles, milk, etc.) thanks to its structure similarities with methionine, and constitutes then a selenium pool.
Selsaf® also brings a source of selenocysteine, which is available for a de novo synthesis of selenocysteine in the animal metabolism, and a quick effect in case of stress. It is indeed necessary for the active site of a major antioxidant enzyme the glutathione peroxidase.
Thanks to its dual mode of action, Selsaf® supports the antioxidant defenses on a quick and long-term basis.
Selsaf® assimilation (Fig. 2)
A) Active absorption:
Bioavailability of Selsaf® active seleno-compounds added to animal feed will first be determined by their absorption in the animal's gut. Once ingested, Selsaf® compounds will be actively absorbed in the small intestine by transporter systems which are shared with amino acids. Their absorption is, therefore, much more efficient than that of sodium selenite, which is transported passively, and sodium selenate, which uses a sodium-mediated carrier mechanism which it shares with sulfur.
B) Muscle storage:
SeMet is also incorporated and stored in the muscles where it can be mobilized during stress (Fig. 3). Under stress conditions, SeMet can be released from this reserve pool in the muscles by catabolism, and can be converted to H2Se for the construction of animal SeCys in the seleno-enzymes (Schrauzer, 2000).
C) Antioxidant defense:
Selsaf® contains a directly available source of active seleno-compounds which can be immediately converted to H2Se, and subsequently used to form seleno-enzymes like GPx. This reduces muscle catabolism under stress conditions, and therefore reduces the effect of stress on farm animal performance. By bringing SeCyst, Selsaf® can enhance the activity of the selenoenzyme GPx, and therefore the antioxidant defense, while reducing the degree of oxidative damage in the animal.
Selsaf® absorption into the blood and assimilation into animal proteins
Selsaf® main benefit is a significant improvement of animal performance. Recent trials comparing the performance of sodium selenite with different organic selenium sources have shown that Selsaf®, in laying hens, improves the survival rate (Fig. 4), and allows a better growth in broiler (Fig. 5).
Recent publications have confirmed the double enhancement of the nutritional and organoleptic quality of food. The supplementation with Selsaf® enriches eggs, milk and meat in selenium, and improves the tenderness (Fig. 6) and the visual quality of meat. Finally, the protection against oxidation does not only apply to the animals. Selsaf® eggs show a reduced lipid oxidation, which offers to the consumer a greater freshness from laying and a better conservation.