Imagine a shrimp farm thriving without harmful ammonia or nitrite, teeming with diverse plankton, and producing healthy, fast-growing Pacific white shrimp (Penaeus vannamei). This is not a fantasy but the reality of the symbiotic system, a revolutionary approach harnessing the power of fermentation and microbial respiration.
Symbiotic systems offer a promising solution by utilizing probiotic-treated plant bran as a source of organic carbon.
A team of scientists from the Institute of Oceanography at the Federal University of Rio Grande conducted a study to evaluate the effect of fermentation (F; an anaerobic phase) and respiration (R; an aerobic phase) processes, as well as different processing times of the symbiotic system fertilizer, on nitrification processes, plankton composition, and Penaeus vannamei growth during the nursery phase, comparing it with a biofloc system.
What is the Symbiotic System?
Traditional shrimp farming often struggles with high levels of toxic nitrogen compounds like ammonia and nitrite, produced by shrimp waste and unconsumed feed. These compounds can harm shrimp health and hinder their growth.
The Symbiotic system introduces bran, such as wheat or rice bran, as a source of organic carbon. This carbon fuels beneficial bacteria that convert harmful nitrogen compounds into harmless forms, creating a cleaner and healthier environment for shrimp.
But the bran needs some preparation before it can work its magic. This is where fermentation and microbial respiration come into play.
Think of it as a pre-digestion process. Probiotic microorganisms like Bacillus and yeasts break down the complex components of the bran into simpler forms, making it easier for other bacteria to use. This also enhances the nutritional value of the bran for the shrimp themselves.
Here, the bran undergoes an energy-generating process. Microorganisms “breathe” oxygen and break down the bran, producing even more readily available nutrients for other bacteria and shrimp.
Previous studies comparing fermentation and respiration in rice bran processing highlight impressive results:
- Increased protein and lipid content: Up to 14.79% more proteins and 10.54% more lipids were observed in processed bran compared to raw bran.
- Improved shrimp performance: Studies using fermented bran for shrimp feeding reported positive results in terms of growth, survival, and nitrogen control.
- Process optimization: Finding the ideal point
While previous research confirms the benefits, there is no one-size-fits-all approach. The key lies in optimizing the fermentation and respiration phases and processing times.
Revealing the best combination
The research aimed to answer the crucial question: What combination of fermentation (F), respiration (R), and processing times produces the best results? They investigated:
- Impact on nitrification process: How well does processed bran control harmful nitrogen compounds?
- Plankton composition: Does processing affect the types and abundance of plankton, a food source for shrimp?
- Shrimp growth: How does processed bran influence the health and growth of Penaeus vannamei during the nursery phase?
The scientists compared different processing times of the symbiotic fertilizer and their impact on shrimp growth, water quality, and plankton composition. They tested various combinations of fermentation and respiration durations against a traditional “clean water” system and a biofloc system (another popular method).
How long should each process last to achieve optimal results?
The scientists compared the effects of different fermentation and respiration durations (12 and 24 hours) in the symbiotic system. They analyzed:
- Nitrification: The efficiency with which the system converted ammonia and nitrite into harmless forms.
- Plankton composition: The diversity and abundance of plankton, a vital food source for shrimp.
- Shrimp growth: Survival rate, weight gain, and overall shrimp health.
The main findings of the study were:
- Faster nutrient management: Treatments with fermentation and respiration (F12+R12 and R24) showed faster control of ammonia, a harmful shrimp waste product.
- Diverse and healthy plankton: Symbiotic treatments fostered a more diverse plankton community, including beneficial amoebas and ciliates, which provide food for shrimp and help maintain water quality.
- Improved shrimp performance: Treatments with shorter fermentation times (F12, F12+R12, F24) resulted in lower feed conversion ratios (FCR), meaning less feed was needed for growth. Additionally, these treatments produced more shrimp compared to the control group.
Comparison with Biofloc
The researchers also compared the Symbiotic system (F12+R12) with a traditional biofloc system. The symbiotic system outperformed biofloc in terms of nitrification efficiency and plankton diversity, leading to better shrimp growth.
“Processing rice bran through a combination of fermentation (anaerobic phase) and respiration (aerobic phase) did not negatively affect shrimp growth and survival,” the scientists concluded.
Symbiotic fertilizers, particularly when processed with fermentation and respiration phases (F12 + R12), have immense potential for shrimp producers. They can improve water quality, enhance plankton composition for better shrimp nutrition, and ultimately increase growth and yield, leading to greater profitability for your shrimp farm.
Thus, the study highlights the potential of symbiotic fertilization, particularly with optimized processing times, to enhance shrimp aquaculture. By utilizing natural processes like fermentation and respiration, shrimp farmers can achieve better shrimp growth, reduce waste, and create a more balanced ecosystem in their ponds.
The study was funded by the Foundation for Research Support of the State of Rio Grande do Sul – FAPERGS, Coordination for the Improvement of Higher-Level Personnel (CAPES), and National Council for Scientific and Technological Development (CNPq).
Wilson Wasielesky Jr
Estação Marinha de Aquacultura, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil
Otávio Augusto Lacerda Ferreira Pimentel, Wilson Wasielesky, Luís Henrique Poersch, Dariano Krummenauer. 2024. Effect of different synbiotic fertilizer processing strategies in Penaeus vannamei intensive nurseries, Aquaculture, 2024, 740667, ISSN 0044-8486, https://doi.org/10.1016/j.aquaculture.2024.740667.