Silkworm pupae meal, a long_standing co_product of sericulture, is increasingly recognized as a valuable insect_ derived protein source for aquafeeds. Its favorable amino acid composition, lipid profile, and generally stable nutrient characteristics make it suitable for reducing dependence on traditional marine proteins. However, protein digestibility remains lower. In this study, a process to enhance the protein and digestibility of silkworm pupae was developed and evaluated for its effectiveness for inclusion in aquafeed as a source of protein replacing animal protein sources such as fish meal. Being derived from a waste by-product, this provides for a sustainable source of protein for aquaculture reducing FIFO ratios.
A controlled 4_ week feeding study was conducted with juvenile Atlantic salmon (Salmo salar) reared in standardized freshwater systems. Diets were produced using a twin_screw extruder with pre_conditioning: a control diet containing 20% fishmeal, and a test diet in which fishmeal was reduced to 15% by incorporating 5% silkworm protein, equivalent to a 25% replacement within the fishmeal fraction. Fish were monitored daily to ensure stable environmental and health conditions throughout the study.
Process development has substantially improved the quality of silkworm protein, enhancing the protein content by 7.8%, digestibility by 10.6%, and reducing the fiber content by 0.7%. Across the 28_ day feeding period, salmon offered the silkworm protein diet showed growth performance equivalent to the control group. Final body weight, specific growth rate and eFCR did not differ significantly between the groups (p>0.05). The proximate composition of the silkworm protein diet remained well balanced, with crude protein around 53.3% and lipid near 18.8%.
These results demonstrate that silkworm protein enables a meaningful reduction in fish meal usage without compromising growth. The findings also emphasize the potential of silkworm protein within circular and resource_efficient feed strategies by converting sericulture byproducts into nutritionally relevant aquafeed ingredients.
Further studies over longer production periods and under health_challenge conditions are recommended to evaluate long_term impacts on growth, and potential health benefits.
Keywords: silkworm protein; insect protein; Atlantic salmon; digestibility; sustainability