Black soldier fly (BSF) larvae meal is widely regarded for its high protein content (>55%), which supports the growth and metabolism of aquatic species.
BSF meal has a well-balanced amino acid profile, similar to high-grade fishmeal, and its protein molecular weight distribution is dominated by free amino acids and di-/tripeptides, making it highly digestible. Additionally, with an average of 13% fat content, including the medium chain lauric acid, BSF meal enhances energy supply, improves palatability, and provides antibacterial properties in aquafeed formulations. Shrimp species and fish like pangasius, tilapia, rainbow trout, and Atlantic salmon are commonly fed with diets containing BSF meal, demonstrating successful outcomes.
An essential but underexposed component of BSF meal is chitin, a compound found in the exoskeleton of the larvae. Studies have suggested that chitin can promote gut health, enhance microbiota, and boost the immune function in fish and shrimp, leading to an improvement of overall health and performance.
For producers like Entobel, who specialize in BSF larvae meal, it is essential to understand the balance between the benefits and potential drawbacks of chitin to ensure its proper use in aquaculture feed formulations. The advantages, such as its prebiotic effects and immune-boosting properties are outlined below. However, excessive amounts of chitin can reduce nutrient digestibility, leading to lower performance outcomes.
Currently, there are no established species-specific guidelines for maximum chitin inclusion levels in aquaculture diets. For now, we rely on existing studies to provide an indication of safe limits. For example, diets for Whiteleg shrimp and Atlantic cod can tolerate up to 5% chitin without negative effect on growth (Rimoldi et al., 2019), while rainbow trout show good performance with up to 3% chitin, but growth is impaired when levels exceed 4.5% (Pascon et al., 2024).
To contextualize, at a 20% inclusion rate of H-Meal, Entobel’s BSF meal, the chitin content is typically 1% in the feed formulation, remaining well within the safe range indication found by available research, thus avoiding the adverse effects of higher chitin levels.
An essential but underexposed component of BSF meal is chitin, a compound found in the exoskeleton of the larvae.
Studies have suggested that chitin can promote gut health, enhance microbiota, and boost the immune function in fish and shrimp, leading to an improvement of overall health and performance.
For producers like Entobel, who specialize in BSF larvae meal, it is essential to understand the balance between the benefits and potential drawbacks of chitin to ensure its proper use in aquaculture feed formulations. The advantages, such as its prebiotic effects and immune-boosting properties are outlined below. However, excessive amounts of chitin can reduce nutrient digestibility, leading to lower performance outcomes.
Gut Health and Microbiota Modulation
The ideal gut microbiota for aquatic species is not definitively established, as it varies across species. However, research shows a strong correlation between gut microbiota composition and gastrointestinal health, with a consensus that a diverse microbial community fosters a healthy gut.
Chitin has a potential prebiotic effect when it can be broken down by chitinolytic activity in the stomach or the intestinal tract. Enzymes such as chitinase and chitobiase, as well as certain bacterial species in the gut, vary in their ability to degrade chitin, depending on the species (Ringo, 2012). The breakdown of chitin results in the production of di-and trisaccharides including chitosan and fermentation products such as propionate and butyrate, short chain fatty acids, which have their beneficial effect on the intestinal lining. Chitin is also being reported to have a bacteriostatic effect on several pathogenic gram-negative bacteria (Pascon et al., 2024), which also helps to modulate the gut microbiota towards preferential bacteria.
Studies have shown that species such as Whiteleg shrimp, Atlantic cod and salmon, red seabream, and Japanese flounder a.o. exhibit this chitinolytic activity, leading to fermentation products that contribute to chitin’s prebiotic effects (Ringo et al., 2016).
The inclusion of 1% of dietary chitin in the diet of Atlantic salmon has led to an increase in beneficial bacteria like Lactobacillus and Carnobacterium, which can enhance digestion and nutrient absorption, while reducing harmful bacteria like Vibrio and Aeromonas (Askarian et al., 2012).
Other species where a rise of beneficial bacterial diversity was observed were Whiteleg shrimp, rainbow trout, tilapia, Japanese seabass (Ringo et al., 2011). These shifts in gut flora enhance immune responses and strengthen the intestinal barrier, leading to greater protection against infections (Zhou et al., 2014).
Immunomodulatory Effects and Disease Resistance
A moderate amount of chitin in the diet is recognized for its immunostimulatory properties in aquatic species. It triggers immune responses by interacting with immune receptors or through its degradation products, which mimic pathogen-associated patterns (Komi et al., 2017). Studies indicate that chitin can enhance both non-specific immune responses and disease resistance in various species.
Chitin promotes the production of cytokines and activates the innate immune system by stimulating macrophages and natural killer cells, aiding aquatic species in fighting off infections (Esteban et al., 2001; Ringo et al., 2012).
Today, for example, chitin has been successfully used as an immunostimulant in shrimp aquaculture to prevent diseases. A study from Wang & Chen in 2005, shows an improved immune function of Whiteleg shrimp, resulting in better survival rates against Vibrio Alginolyticus.
Also in fish, yellowtail for instance, chitin injections increased protection against P. piscicida (Kawakami et al., 1998). Another study involving common carp revealed that chitin enhanced immune responses such as lysozyme and phagocytic activity and respiratory rates (Gopalakannan & Arul, 2006). In rainbow trout, dietary chitin supplementation has been shown protection against Vibrio anguillarum (Sakai et al., 1992).
Discussion
According to available research, chitin, a key component of Black Soldier Fly larvae meal, may offer promising benefits in aquaculture, particularly in enhancing gut health, modulating microbiota and boosting the immune system of fish and shrimp.
However, potential drawbacks, including reduced nutrient digestibility, underscore the importance of managing the chitin inclusion in feed formulations. While existing research indicates that moderate amounts of chitin can be safely utilized, there is a need for species-specific guidelines to fully harness its benefits without compromising growth and performance. Consequently, further scientific research is essential to explore the dose-response relationship as well as to substantiate the potential benefits. Studies that focus on chitin from insect sources, compared with chitin derived from crustaceans is also needed to fully explore its unique properties. By backing up the potential of insect-derived chitin with solid scientific evidence, we can unlock new opportunities for sustainable and effective aquaculture practices.
Written by Gil De Clercq – Entobel International Sales Manager
Published in Aquafeed Magazine Vol 16 Edition 4 2024
