Hilyses®: a source of nucleotides and digestible nutrients for shrimp nutrition

For a long time, the most common method for dealing with the occurrence of bacterial infections in aquaculture was the administration of antibiotics. However, aquaculture faces serious problems due to various adverse effects of these drugs such as accumulation in the tissue, environmental microbial flora. In the other hand, to use antibiotic or vaccine for fish is expensive and in many farms unavailable (Yousefian and Amiri, 2009), however, the use of substances or nutrients incorporated into the feed to improve the survival rate, disease resistance, and growth of shrimp has been used more and more and successfully.

Hilyses®, produced by ICC Brazil, contains hydrolyzed RNA from Saccharomyces cerevisiae yeast. Special enzymes are used in order the digest the RNA into smaller fractions, for some specific enzymes, resulting in free nucleotides and nucleosides. Hilyses® is also composed of the yeast cell wall that has a high β-glucans amount, which is an immunostimulant to activate the T cells present in the intestine, triggering an activation of the innate immune system. Shrimp are apparently entirely dependent on a non-specific immune mechanism to resist infections (Hertrampf and Mishra, 2006). This stimulation of the immune system can leave it better prepared to face possible infections by pathogens. The cell wall also contains mannan oligosaccharides (MOS) which it will prevent pathogen colonization in the gut as it offers a binding site to harmful bacteria that possess type 1 fimbriae present in the intestinal tract.

Another benefit of Hilyses® is that the intracellular content is fully available, i.e., offers high amounts of small chain polypeptides and free amino acids. These nutrients are readily available for absorption in the gut and metabolism utilization. Among these amino acids, there are high levels of glutamic acid (glutamine and glutamate), which gives large support to gut (as amino acid and energy source) and also has excellent palatability, leading to an increase in feed intake. The nucleosides guanosine monophosphate (GMP) and inosine monophosphate (IMP) also contribute to improving the palatability. If the feed intake is stimulated, there is consequently a better resistance to the challenges and also a higher growth rate.

The free nucleotides from Hilyses® can be used by the salvage pathway in cells. By this metabolic pathway the body can synthesize nucleotides with less energy cost as a result of the recycling of free bases and nucleotides from metabolic degradation of nucleic acid from dead cells and/or from the diet, especially in tissues with high cell turnover and limited capacity for synthesis of purine and pyrimidine by via de novo (such as intestinal epithelial cells, hepatopancreas cells, hemolymph cells and immune system), where the requirement of these bases is high. When endogenous supply is insufficient for normal function, nucleotides become semi-essential nutrients or “conditionally essential” (Carver and Walker, 1995). This is especially the case in certain disease states, periods of limited nutrient intake or rapid growth (juvenile stages). Also, dietary nucleotides appear to be important to support optimal growth and metabolically functions, such as lymphocytes and macrophages.

Nucleotides can combine nutritional as well as sanitary benefits when added to feeds. The quality of the product, the proper mixture and administration will determinate the results. All Hilyses® components result in a synergistic effect improving the gut integrity and health, higher cell proliferation and strengthening the immune system; which is a powerful ally in improving productivity in shrimp farming.

Carver, J.D, and Walker, W.A. (1995). The role of nucleotides in human nutrition. Nutritional Biochemistry. Vol. 6, pp. 58-72.

Hertrampf, J.W. and Mishra, S.K. (2006). Benefits of nucleotides in shrimp farming. Feed Tech. Vol. 10.9, pp. 27-30. www.AllAboutFeed.net

Yousefian, M. and Amiri, M.S. (2009). A review of the use of prebiotic in aquaculture for fish and shrimp. African Journal of Biotechnology. Vol. 8 (25), pp. 7313-7318.