Lallemand Animal Nutrition 2nd Aquaculture Technical Meeting, hosted in Chennai, India, in March 2016 and dedicated to shrimp farming. More than 250 participants from Europe, Latin America, Middle East and South East Asia attended this event. The meeting offered an overview of the latest findings in shrimps ponds and digestive microbial ecosystems, and international speakers discussed the importance of managing these ecosystems to address some of today’s challenges of shrimp production: novel pathogens (EMS, EHP…), water quality and sustainability. Microbial based approaches such as bioremediation, probiotic and selected microbial derivatives emerged as profitable and sustainable solutions. This was demonstrated along the day through experts’ testimonials and many production and research trials results showing benefits on performance and disease prevention. This event was also the opportunity to reward leading aquafeed manufacturer Avanti Feeds Ltd, for its long-term cooperation.
From pond to gut, the importance of managing microbial ecosystems
From pond water to shrimp gut, microorganisms are present everywhere and microbial ecosystems play a key role in maintaining shrimp health and performance. As Dr Mathieu Castex, Scientific Director at Lallemand Animal Nutrition, explains, the pond is a complex ecosystem, involved in organic matter treatment and nutrients recycling or removal, especially nitrogen. Together with phytoplankton, bacteria are dominating this ecosystem. The pond microbial communities are part of the food chain, contribute to biological processes and play a key role in sanitary conditions: the positive flora help keep pathogens under control. However, a shift in this ecosystem balance can lead to the over-development of undesired microorganisms, including potential pathogens, or affect nitrogen cycle and organic matter removal, with impact on health and performance.
Dr Castex also discussed the latest findings about the shrimp digestive microflora. Today, little is known about the role of this microflora in shrimp, but current findings support a fundamental role in mediating shrimp health. In particular, various publications show that probiotics in feed have the ability to modulate shrimp intestinal microbiota. For instance, several studies have revealed that Pediococcus acidilactici MA 18 5 M (BACTOCELL®) has a positive impact on oxidative stress reduction, which in case of pathogenic infection, can lead to improve survival.
Controlling new shrimp diseases
Dr. L. Tran, from Aqua Mekong Laboratory, Vietnam, discussed the latest understanding on novel diseases in shrimp, such as EMS/AHPND, white feces disease and EHP/ microsporidia. As EMS, white feces disease affects shrimps gut and thus performance and survival.
Dr Tran reminded that shrimp diseases were transmitted through water, feed, cannibalism, fecal matter, biofilm…According to him, prevention is the keyword. He shared some practical management approaches for white feces and EMS diseases prevention.
Today, Dr Tran and his team are busy working on new strategies to control these bacterial infections. In particular, probiotics gave some very good increase in survival in a challenge model. He concluded that there is still a lot to do to know more about EMS and White feces diseases in order to design proper efficient strategies to decrease their impact. According to him, there is no single solution and a holistic approach is probably the way forward.
EHP stands for Enterocytozoon hepatopenaei, a microsporidian parasite. Qualified by Dr Tran “the hidden killer”, this new disease infects young shrimp in particular. The infection spreads through the feed and the water especially via the fecal matters. To date, the mechanisms of this infection are still poorly understood. However, Dr Tran suggests some environmental measures and practical solutions in hatcheries to decrease the impact of EHP and improve the environment quality.
The control and management of microbial ecosystems, from pond to gut, appear as an interesting approach to limit the development and spreading of pathogenic bacteria. Some recent developments in this direction were provided along the meeting.
New bioremediation solutions
The bioremediation concept has been applied to aquaculture for decades with the aim to facilitate the management of organic matter accumulation and nitrogen compounds in the culture systems (water and pond bottom quality). Dr Castex described some research work ongoing at the Lallemand AquaPharm research platform, in Scotland, aimed at selecting specific heterotrophic bacteria strain for bioremediation. Selection criteria are based on selecting competitive bacteria, well adapted to various environments (salinity, low oxygen etc.), safety (absence of antibiotic resistance and toxin genes, etc.), vibrio antagonism activity and organic matter and nitrogen removal.
Stéphane Ralite, Aquaculture Product Manager at Lallemand Animal Nutrition gave a concrete example with the methodology applied to develop novel bioremediation solution. Thousands of bacteria strains were screened from the AquaPharm collection in order to select the best candidates with regards to the criteria listed above. The selected bacteria association (LALSEA® Biorem), was validated through in vitro and in vivo trials, especially in controlling organic matter degradation, nitrogen removal and sludge quality.
Pond microbial management involves both biological tools such as bioremediation bacteria but also practical management tools. A successful example was provided by Werner Jost, from Camanor, in Brazil. Following White Spot disease outbreak in Brazil, this innovative shrimp farm developed an original water recirculated system called “AquaScience”. This 100% recirculation system is a unique and advanced way to produce shrimps at a density of 250 shrimps/m², without water exchange or sludge release in the environment in a chemical-free environment. Camanor is using bioremediation and probiotic solutions (including Pediococcus acidilactici MA 18 5 M) to help balance microbial ecosystems and control water quality.
Managing gut microbial ecosystems
The digestive tract of shrimp is the target for major diseases. At a time when the use of antibiotics must be dramatically controlled, the management of gut microbial ecosystems in a positive way, through probiotics in feed, is a promising approach. As an example, Henrik Aarestrup, from Biomar, in Denmark, presented the company’s functional feed concept. H. Aarestrup shared his experience of using probiotic in fish feed and in shrimp larvae range. Results showed that BACTOCELL® contributes to reduce deformities in fish, reduce dependence upon live feed, improve survival, and improve farm profitability.
S. Ralite also described the development of new solutions to target vibrio in shrimps. Using AquaPharm screening platform, researchers screened the best candidates for vibrio antagonism. More than 300 bacteria strains were tested and four were shortlisted and transferred to in vivo testing. Finally, BACTOCELL prove the most effective antagonist effect on vibrio control in vivo and at farm level. In addition, scientists at Lallemand used a different screening approach, based on the in-depth characterization of yeast fractions and in particular their binding and immune modulation properties, to develop a synergistic alliance of specific strains of inactivated yeast. Called YANG®, this new solution was shown to contribute to improving binding capacities, immune modulation and mucus production in fish. Regarding shrimps, scientists conducted in vivo trials in Vietnam and tested a combination of YANG with two bacteria from Aquapharm or YANG alone during an EMS challenge. In both cases, shrimp survival was significantly improved.
In conclusion, shrimp farming today is challenged by new pathologies while environmental pressure and food demand are increasing. The various testimonials and trial results shared indicate that the use of specific microbial solutions in feed, together with a control of the environment through management practices and microbial control of the water and pond bottom, can participate to optimize shrimp performance and health through microbial ecosystems managements, in a holistic and sustainable way.
For more information about the presentations and trials data presented contact Stéphane Ralite, Aquaculture Product Manager, Lallemand ANimal Nutrition.