Although traditionally associated with sleep, melatonin is becoming a powerful tool in aquaculture, particularly for stimulating the growth and metabolism of aquatic animals.
Research published by scientists from East China Normal University and the Chinese Academy of Fisheries Sciences aimed to investigate the impact of melatonin (MT) in the diet on the growth physiology and lipid metabolism of white shrimp (Penaeus vannamei).
Why is melatonin important for shrimp?
Scientific studies have shown that including melatonin in the diet of various aquatic species, including crustaceans, can significantly improve their growth, survival, and overall health.
In this way, supplementing shrimp feed with melatonin can generate a cascade of positive effects, from improved survival rates and increased appetite to better immune function and optimized lipid metabolism.
Shrimp, like all living organisms, depend on a delicate balance of internal processes to thrive. A crucial aspect is lipid metabolism, how shrimp handle fats to obtain energy and form tissues. This intricate dance involves enzymes such as lipases, carnitine palmitoyltransferase 1 (CPT-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). When this interaction fails, growth stops, and shrimp become vulnerable to stress and diseases.
Melatonin to the rescue
Research suggests that melatonin acts as a metabolic regulator, adjusting the activity of these key enzymes. By gently pushing the system toward a more efficient use of fats, melatonin promotes optimal growth and development. Studies have shown that aquatic animals fed with melatonin-enriched diets exhibit:
- Increased weight and body size: Melatonin appears to stimulate appetite and improve food utilization, leading to faster growth and larger shrimp.
- Improved lipid metabolism: Melatonin seems to optimize the activity of enzymes involved in the breakdown and utilization of fats, turning food into fuel more efficiently.
- Enhanced stress resistance: The antioxidant and immune-boosting properties of melatonin help shrimp cope better with environmental stressors, further promoting healthy growth.
Study results
To understand how melatonin acts, researchers delve into the intricate world of shrimp physiology. By measuring enzyme activity, analyzing tissue composition, and monitoring biochemical markers, they solve the puzzle of how this seemingly sleepy hormone drives accelerated growth.
The study focused on Pacific white shrimp (Penaeus vannamei), a commercially important species. Researchers divided the shrimp into six groups and fed them diets with different levels of melatonin. They then monitored their growth rate, survival, and key metabolic markers.
Study results indicate that shrimp fed diets supplemented with melatonin showed:
- Significant growth boost: Shrimp fed the optimal dose of melatonin (82.7 mg/kg) grew faster and larger than their counterparts without melatonin.
- Improved survival: Melatonin’s immune system enhancement properties led to higher survival rates.
- Enhanced lipid metabolism: Melatonin optimizes the digestion and utilization of fats, leading to more efficient energy production.
- Increased omega-3 levels: Shrimp treated with melatonin also had higher levels of DHA and ARA, essential omega-3 fatty acids known for their health benefits.
The research suggests an optimal melatonin concentration of 59.59 to 71.97 mg/kg for P. vannamei, below which offers minimal benefits, while above may be harmful.
Application in shrimp farming
With its promise to produce healthier and faster-growing shrimp, melatonin has the potential to revolutionize the shrimp farming industry. By incorporating this readily available and relatively inexpensive additive into shrimp feed, aquaculturists could:
- Increase production: More shrimp, in less time, translates to better yields and greater profitability.
- Improve nutritional value: Shrimp fed with melatonin may exhibit higher protein content and healthier fat profiles, making them a more nutritious food source.
- Promote sustainability: Efficient growth and increased stress resistance can lead to reduced waste and a more sustainable aquaculture approach.
Research on the benefits of melatonin for shrimp is still evolving, but the results are promising. As scientists continue to unravel the mechanisms behind its effects, we can expect even more efficient and sustainable methods for shrimp farming.
Conclusion
“We evaluated the effects of different concentrations of melatonin on the growth physiology and indicators related to the lipid metabolism of P. vannamei. The dashed line model based on MT level in the diet versus WGR, SGR, and FCR suggested that MT supplementation in the diet in the range of 59.59 to 71.97 mg/kg is suitable for P. vannamei,” concluded the researchers.
The study adds to the growing body of evidence highlighting the potential of melatonin as a valuable tool in shrimp aquaculture. By incorporating melatonin into food formulations, shrimp farmers can enhance growth performance, improve stress resistance, and optimize lipid metabolism in their shrimp, leading to a more sustainable and profitable industry.
While more research is needed to optimize melatonin use and fully understand its mechanisms, early results are promising.
The study was funded by the Agriculture Research System of Shanghai, China, and the Young Elite Scientists Sponsorship Program by CAST.
Contact
Y. Li
Fishery Machinery and Instrument Research Institute
Chinese Academy of Fisheries Sciences
63 Chifeng Rd., Shanghai 200092, China.
Email: liyiming@fmiri.ac.cn
Y. Zhao
School of Life Science
East China Normal University
500 Dongchuan Road, Shanghai, China.
Email: ylzhao426@163.com
Reference
Ye, Y., Li, S., Zhu, B., Yang, Y., Du, X., Li, Y., & Zhao, Y. (2024). Effects of dietary melatonin on growth performance, nutrient composition, and lipid metabolism of Pacific white shrimp (Penaeus vannamei). Aquaculture, 578, 740095.
