Aquaculture is expanding rapidly to meet global protein demands, but current feed ingredients like fish meal and soybean concentrate have severe environmental impacts. Therefore, identifying sustainable alternative protein sources is essential. This study investigated whether white protein (WP) concentrate extracted from alfalfa (Medicago sativa) could serve as a viable substitute.
Results showed that:
- the WP20 diet had significantly higher water stability, likely due to pre-extrusion rather than WP content itself.
- No major differences were found in bulk density or expansion ratio, though higher WP levels tended to make pellets denser and softer.
- In terms of growth, fish fed WP5 and WP10 performed similarly to the control, while WP20 fish showed reduced growth indicators, such as weight gain, feed intake, and specific growth rate, along with lower nutrient digestibility.
- Overall, WP concentrate appears suitable for inclusion in rainbow trout feed at up to 10%, but further long-term studies at different life stages are recommended to confirm these findings.
The report was compiled by Nathalie Navarrete, SLU – Department of Animal Science and Welfare within the Green Valleys project. The study is funded by Interreg Öresund-Kattegatt-Skagerrak together with SLU and the Västra Götaland regionen.
Click below to read the full report here on Bringing Green Valleys to aquaculture.
