Nutritional composition of black soldier fly larvae feeding on agro‐industrial by‐products

What is it about?

Black soldier fly (BSF) larvae, Hermetia illucens L. (Diptera: Stratiomyidae), bio‐convert organic side streams into high‐quality biomass, the composition of which largely depends on the side stream used. In the present study, BSF larvae were reared on feed substrates composed of dried brewers’ spent grains, each supplemented with either water, waste brewer’s yeast, or a mixture of waste brewer’s yeast and cane molasses to obtain 12 different substrates: barley/water, barley/yeast, barley/yeast/molasses, malted barley/water, malted barley/yeast, malted barley/yeast/molasses, malted corn/water, malted corn/yeast, malted corn/yeast/molasses, sorghum‐barley/water, sorghum‐barley/yeast, and sorghum‐barley/yeast/molasses. The crude protein, fat, ash, and mineral contents of the BSF larvae fed each feed substrate were quantified by chemical analyses. The effect of substrate, supplementation, and their interaction on crude protein, fat, and ash contents of BSF larval body composition was significant. Calcium, phosphorus, and potassium were the most abundant macrominerals in the larvae and their concentrations differed significantly among substrates. These findings provide important information to support the use of BSF larval meal as potential new source of nutrient‐rich and sustainable animal feed ingredients to substitute expensive and scarce protein sources such as fishmeal and soya bean meal.

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Why is it important?

Our findings show that BSF larvae may be mass‐produced on these substrates for animal feed, providing an alternative strategy for managing agro‐industrial side streams, when the conventional uses of these substrates such as direct feeding to livestock are not sufficient.