Application of synbiotics in shrimp culture

Synbiotics is a mixture of probiotics and prebiotics which beneficially affects the host by improving the survival and implantation of useful live microbiota in the gastrointestinal tract and improves digestion and absorption of the host.

Dr. Amit Ranjan
Assistant Professor
Tamil Nadu Dr. J. Jayalalithaa Fisheries University (TNJFU)
Thangaraju Thiruvasagam, Ph.D.
Research Scholar
Tamil Nadu Dr. J. Jayalalithaa Fisheries University (TNJFU)

Aquaculture is one of the fastest-growing animal food production sectors worldwide. Outbreak of several diseases hindering the expansion and development of aquaculture. Traditionally, antibiotics have been supplemented in aquafeeds for prevention and/or treatment of bacterial disease of aquatic animals but antibiotics have been suspended from usage in the aquaculture industry since 2004. Therefore, during farming operations, preventing pathogen propagation and enhancing aquatic animal immunity without chemotherapeutic interventions are primary concerns.

SYNBIOTICS
Synbiotics is a mixture of probiotics and prebiotics that beneficially affects the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract, by selectively stimulating the growth and/or by activating the metabolism of one or a limited number of health-promoting bacteria, and thus improving host welfare. Although, synbiotics concepts appeared early, the first introduction of a synbiotic was reported in L. vannamei in 2009. As probiotics alone does not survive well in the GIT without its prebiotic, it has been suggested that the combination of probiotic and prebiotic as synbiotics might be more effective than either a probiotic or prebiotic alone. In synbiotics, the prebiotic compound selectively favours the growth of probiotics and their metabolite production and it can be the safest and most effective solution for combating the colonization and infection with enteric pathogens particularly bacterial pathogens. Synbiotics provide more additive benefits in growth performance, feed conversion ratio, hematological and biochemical parameters than probiotic and prebiotic individual use of these additives. Moreover, synbiotic could increase the digestibility and availability of many nutrient elements such as vitamins, mineral elements, and proteins. The major purpose of using synbiotic is to maintain a favourable relationship between beneficial and pathogenic microorganisms that constitutes the flora of the intestine and skin of aquatic animals. Therefore, a synbiotic is expected to have a few specific properties to impart a beneficial effect. These properties include a) Competitive exclusion b) Antagonism to pathogens c) Adhesion and d) Immunity stimulation. Synbiotics are designed to beneficially affect the host such as Improving survival and implantation of probiotics in the colon, selectively stimulating the growth or activating the metabolism of health-promoting bacteria (probiotics) in the colon and improving the microbial composition of the GI tract.

COMPARATIVE OVERVIEW OF PROBIOTIC, PREBIOTIC AND SYNBIOTICS
Unlike probiotics, prebiotics do not add to an existing colony of bacteria, rather they provide nourishment for existing flora, allowing the colony to grow naturally and flourish. During synbiotic dietary treatment, prebiotics in the form of synbiotics are hydrolysed to their respective sugars in the intestinal tract of the host and are subsequently utilized as a source of carbon to increase the biomass of bacteria. As probiotic is principally active in the small intestine and prebiotic is only effective in the large intestine, the combination of the two may give a synergistic influence. Probiotic is a live microbial food ingredient which is beneficial to host while prebiotic is a non-digestible food ingredient which beneficially affects the host by selectively stimulating the growth and activity of one or a limited number of microorganisms in the colon having the potential to improve host well-being nevertheless, synbiotic is a mixture of probiotic and prebiotic which beneficially affect the host and thus improving host health.

Effects of synbiotics application in shrimp culture:
• Synbiotics beneficially affects the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract and improves digestion and absorption of the host.
• Synbiotics serve as a source of exoenzymes which induces the hosts’ digestive enzymes and improves the absorptive ability of the host.
• Synbiotics produces substances that stimulate the immune systems, thus enhancing the host protection against infection. Synbiotics stimulate the immunity of organisms in two ways. The flora from synbiotic migrates throughout the gut wall and multiplies to a limited extent and when they die, they release antigens which when absorbed stimulate the immune system.
• Synbiotics can trigger encapsulation and phagocytosis processes in shrimp.
• Synbiotics were found to be useful not only as food but also as biological controllers of fish disease and activators of nutrient regeneration.
• Deterioration of soil and water quality in aquaculture systems is often associated with the decomposition of organic matter over time. The use of synbiotics can enhance the rate of degradation of organic matter, increase the level of dissolved oxygen, eliminate undesirable waste products (nitrite ammonia, carbon dioxide, and sulfide), reduce the proportion of blue-green algae and increase aquatics production.
• The application of synbiotics have proven to be effective in shrimp hatcheries by outcompeting pathogenic bacteria for nutrients and other resources, thus reducing the risk of disease and improving larval growth.

DOSAGES OF SYNBIOTICS IN SHRIMP FARMING
The dosage of synbiotics varies depending on the specific products available from different companies, as well as the particular diseases affecting the cultured system. For instance, a product called “Gut Health” from Charoen Pokphand Foods (CPF) functions as a synbiotic, comprising beta-glucan as a prebiotic along with various bacterial strains as probiotics. Typically, the recommended dosage of “Gut Health” for regular usage in a standard pond environment range from 5 to 10 grams per kilogram of feed per meal per day. However, in cases where the pond is afflicted with white gut and white faecal infections, the recommended dosage increases to about 10 to 15 grams per kilogram of feed per two meals per day.

PROBLEMS AND CHALLENGES
Although the use of synbiotics presents enormous benefits to the aquaculture industry, its application is equally presented with problems and challenges. The use of synbiotics in aquaculture comes with extra costs to aquaculture farms. This is primarily due to the necessity of carefully assessing and evaluating new strains for both safety and efficacy before incorporating them into products. In addition, companies that produce these products need to ensure modern techniques are used in their production for safe and quality products. Another challenge in the use of synbiotics in shrimp farming is their preparation and storage. Variations in size, age, and stage of shrimp culture further complicate the selection process, necessitating careful consideration to optimize the benefits of synbiotic supplementation in shrimp farming.

CONCLUSION
The synbiotic has the ability to regulate the composition of the microbiota by prebiotic and probiotic microorganisms is an interesting approach in the control and treatment of some major diseases in shrimp farming owing to its beneficial effect on the host organism. However, its use in the commercial shrimp culture has yet to be realized in its full strength.

References:
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About Thangaraju Thiruvasagam
Thangaraju Thiruvasagam, is a Ph.D. research scholar in the Department of Fish Nutrition and Feed Technology at Institute of Fisheries Post Graduate Studies of Tamil Nadu Dr. J. Jayalalithaa Fisheries University (TNJFU), India.

About Dr. Amit Ranjan
Dr. Amit Ranjan is an Assistant Professor in the Department of Fish Nutrition & Feed Technology at the Institute of Fisheries Post Graduate Studies of Tamil Nadu Dr. J. Jayalalithaa Fisheries University (TNJFU), India. His research focus is on fish and shrimp nutrition, where he conducts both strategic and applied research. With his extensive experience in commercial culture of shrimp and freshwater fish, he has published several research papers in international peer-reviewed journals and serves as a reviewer for over 50 international peer-reviewed journals.