Properties of Aquafeed Pellets Containing Black Soldier Fly Larvae

A lot has been discussed about the production of fish (aquaculture) when using feed derived from BSF. In fact, a recent article indicated Protix will be producing salmon (a traditional model for BSF) fed BSF feed. In fact, they are branding it due to its uniqueness (in a very good way) as related to production.

However, for most, the actual appropriate means for producing fishmeal either with complete or partial replacement by BSF meal is not known.

A study that was just published in the Journal of Insects as Food and Feed addressed this topic for feed produced with BSF as well as crickets. 

Physico-chemical properties of extruded aquafeed pellets containing black soldier fly (Hermetia illucens) larvae and adult cricket (Acheta domesticus) meals

What I found interesting about this paper is the authors focused on the actual production of the pellet to be fed to fish. They addressed some features that I believe many researchers historically have not considered.  

They examine:

1. Floatability
2. Expansion rate
3. Bulk density
4. Durability index
5. Water absorption index
6. Water solubility index
7. Water stability of extruded pellets

Why is this important? While BSF can be mass produced- how do we present them to fish or other mass produced species in aquaculture in order to maximize production, conversion, and production.
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What did they find (information verbatim from the abstract)?

• Pellet floatability was not influenced by the type of insect meal but the interaction between level of inclusion and moisture content of the feed at extrusion.
• Pellets with high floatability >90% were produced from all feed blends at 30 g/100 g moisture content.
• Expansion ratio, was not influenced by type of insect meal or the level of inclusion but by the moisture content whereby feed blends extruded at 30 g/100 g moisture gave pellets with high expansion ratio ~60%.
• Bulk density was influenced by the interaction of the three factors.
• Pellet durability and water absorption indices were not influenced by the investigated factors or their interactions.
• Processed pellets were generally highly durable (99%) out of water, but the stability in water was significantly influenced by the interaction of type of insect meal level of inclusion and moisture content at extrusion.
• Water solubility increased with increasing extrusion moisture. Overall, it was possible to process good quality extruded pellets with 75% BSFM or 75% ACM at 30 g/100 g feed moisture. 

What does it mean? From my perspective, it means several things;
1) Mechanization: industry needs to develop appropriate equipment for production of BSF meal for aquaculture (maybe equipment already exists-  but BSF companies will need to decide if they want to produce the meal or sell to another company for mass production.

2) Economics: Either decision listed in the first point impacts price of the product. What is optimal for the aquaculture industry still needs to be determined. Is BSF a higher quality product for aquaculture (rhetorical question)?  We also know this will be dependent on the species being mass-produced. Some are higher value per ton than others. 

3) Genetics & Nutrition: Does quality of the BSF produced impact all of the factors previously investigated for this sample of BSF? I suspect it does as the protein and fat content will vary across production lines (depending on genetics of population- shout out to my colleagues Christoph Sandrock and Christine Picard for their population genetics research with BSF) as well as what they are fed.

4) Durability: This is not with regards to durability of the pellet produced but more about shelf-life. How to produce this product and then store it prior to use. Are there conditions under which the feed will need to be stored in order to prevent nutrient or product degradation.

5) Volume: One thing everyone should always be thinking about- how much BSF do you need to produce in order to supply an aquaculture production facility?  The math is mind-boggling! 

These are a few potential items to consider with production... and I am sure there are many more. So, if you think of something... please reply and share with everyone.