black soldier fly larvae meal

As the global population continues to grow, food demand continues to rise. Aquaculture, as an important food production sector, plays a key role in meeting people's demand for animal protein. However, aquaculture faces many challenges, among which the high cost of feed and the scarcity of feed raw materials are particularly prominent. Take Cameroon as an example. This country has abundant water resources and many fish species, but due to feed problems, its fish production is far below potential production capacity, and it suffers huge economic losses every year.

In aquatic feed, fish meal has always been a popular source of protein because it contains rich protein and fatty acids, has a balanced amino acid composition, is easy to digest and has good palatability. However, overfishing of wild fish used to produce fish meal has brought great pressure to the ecological environment. At the same time, the continuous rise in fish meal prices has also squeezed the profit margins of aquaculture and even triggered competition for resources between aquaculture and human consumption. Therefore, finding a nutritious and sustainable fish meal substitute has become an urgent problem to be solved in the field of aquaculture.

In this context, insects have gradually attracted attention as feed ingredients, among which black soldier fly larvae (BSFL) have become a potential substitute for fishmeal due to their rich nutrition, rapid growth, low ecological impact and high consumer acceptance. However, there are still some obstacles to the application of black soldier fly larvae in aquatic feed, such as palatability, digestibility, chitin content, and different processing methods may also affect their quality.

In order to solve these problems, researchers from the Faculty of Agriculture and Agricultural Sciences of the University of Yaounde in Cameroon and other institutions conducted an in-depth study. Their research results were published in the journal Discover Animals, bringing new hope for the sustainable development of aquaculture.

Research Methods

The researchers conducted a 120-day feeding experiment in the aquaculture facilities of the Faculty of Agriculture and Agricultural Sciences of the University of Yaounde in Cameroon. The black soldier fly larvae used in the experiment came from a pre-established black soldier fly population, and the larvae fed on a mixture of fruit waste and cow dung. The researchers used three different processing methods (boiling, baking and sand baking) to treat the larvae, and the chemical composition and microbiological analysis of the treated larvae were performed.

In terms of feed formulation, the researchers prepared a control feed with fish meal (FM) as the main protein source, and also prepared different experimental feeds with black soldier fly larvae meal (BSFLM) replacing 50%, 75% and 100% of the fish meal respectively. These feeds are isonitrogenous (400g/kg crude protein) and isocaloric (3000kcal/kg metabolizable energy). The experiment selected African catfish (Clarias gariepinus) juveniles and randomly assigned them to different plastic aquaculture tanks, with 8 fish in each tank. During the experiment, the researchers monitored the water temperature and pH value every day, cleaned the tanks regularly and changed the water to avoid contamination. The fish were weighed and counted weekly, and their growth performance indicators, including survival rate, weight gain, specific growth rate, feed conversion rate, etc., were calculated. After the experiment, the visceral-somatic index (VSI), hepato-somatic index (HSI) and meat quality of the fish were also evaluated, while the fish meat was sensory evaluated, and an economic analysis and sustainability assessment were conducted.

Research Results

· Effects of processing methods on black soldier fly larvae: Different processing methods had significant effects on the nutritional composition and microbial composition of black soldier fly larvae. Boiling significantly increased the dry matter and organic matter content of the larvae, but reduced the crude protein and fat content; baking resulted in the highest protein content. In terms of mineral content, sand-baked larvae had the highest calcium content, boiled larvae had the highest iron content, and baked larvae had the highest potassium, sodium and phosphorus contents. Microbial analysis showed that Enterobacter and Salmonella were not detected in the larvae treated with baking and sand-baking, the highest content of Escherichia coli was found in sand-baked larvae, and lactic acid bacteria were only detected in boiled larvae.

· Effect of black soldier fly larvae meal on growth of African catfish: In the feeding experiment, catfish fed with standard commercial diet (CD), BSFLM75 and BSFLM100 did not die during the experiment, while catfish fed with local diet (BSFLM0) had the lowest survival rate. Although the commercial diet gave the best performance in terms of weight gain, specific growth rate and body length of catfish, these indicators were significantly improved at higher BSFLM replacement levels (75% - 100%) compared with the local control diet (BSFLM0). In addition, catfish feed intake and feed conversion rate also improved with increasing BSFLM replacement levels.

· Effect on body index and meat quality of catfish: Catfish in the BSFLM50 diet group had the highest visceral body index (VSI), while catfish in the commercial diet group had the highest hepatosomatic index (HSI). In terms of meat quality, most consumers found the catfish fed different diets to have a good taste, except for the BSFLM75 group, where only 49% of tasters found the fish meat to have a pleasant taste. Most consumers found the fish meat to be juicy and predominantly white in color. Overall, catfish acceptance was high in all diet groups, with the BSFLM75 group having the highest acceptance.

· Economic feasibility and sustainability: Economic analysis showed that the addition of BSFLM to feed reduced catfish production costs and improved profitability. The BSFLM75 and BSFLM100 diet groups had lower feed costs and feed intake and the highest profitability. At the same time, the fish feed input-output ratio (FIFO) of fish decreased linearly with increasing levels of BSFLM in the feed, indicating that the use of BSFLM improved the sustainability of the culture system.

Conclusions and Significance of the Study

This study showed that black soldier fly larvae meal (BSFLM) is a suitable protein source for fishmeal replacement, especially at higher replacement levels (75% - 100%), which can significantly improve the growth performance, feed conversion rate and survival rate of African catfish, while reducing production costs, improving profitability and sustainability. Different larval processing methods affect the nutritional content and microbiological quality of black soldier fly larvae, so standardized production processes are needed to fully realize their potential in aquaculture. In addition, the study also found that BSFLM has a positive effect on the meat quality and sensory characteristics of catfish, which can help improve consumer acceptance.

However, the study also has some limitations, such as the results may not be applicable to all farming conditions, the limited number of experimental animals may affect the accuracy of the results, the long-term effects on health and reproduction have not been explored, and farmers' willingness to accept insect-based feeds also needs further study. Nevertheless, this study provides a new sustainable development direction for aquaculture, which is expected to reduce dependence on wild-caught fish and promote the sustainable development of aquaculture. In the future, more research is needed to address these issues and promote the widespread application of black soldier fly larvae powder in aquaculture.