Enhanced Mineral Digestibility, and Tissue Retention in Rainbow Trout ( <i>Oncorhynchus Mykiss</i> ) Fed Lupin Meal with a Solid-State Fermentation (SSF) Dietary Supplement

Abstract Alternative plant proteins to fishmeal remain a paramount feature for future aquaculture development to attain sustainable production goals. Consequently, there is pressure to improve their quality and raise protein contribution by removing antinutrients (ANFs) for maximum assimilation to be achieved. This is particularly relevant to various plant byproducts due to their lower digestibility for most fish species and significant anti-nutritional factors. To address this limitation, one option is to employ solid-state fermentation (SSF) dietary supplements. A nutritional trial was conducted to assess the incorporation of white lupin ( Lupinus albus ) as a European protein-rich ingredient and a commercial bioactive feed supplement in diets for rainbow trout ( Oncorhynchus mykiss ). The trial was designed to determine the effect of including 30% white lupin as a fish meal replacement with various levels of a commercial SSF product at 0, 0.1 and 0.5% dietary inclusion level on macro-nutrient, mineral digestibility and tissue retention in rainbow trout. The results indicated that rainbow trout fed with 30% of white lupin and addition 0.5% of SSF, were closer in performance to those fed with a high-grade fishmeal (FM) reference diet. In addition, significant increases in feed utilization, and especially mineral retention were noted for this product. Results of the study indicated that supplementing SSF to plant-based diets is beneficial to reduce the negative effect of ANFs and to improve nutrient and specific mineral utilization and retention for trout in key tissues. Also, our findings demonstrate that lupin meal has a promising potential for use in trout feeds with strategic importance for the aquaculture industry.