Growth and Welfare of Rainbow Trout (<i>Oncorhynchus mykiss</i>) in Response to Graded Levels of Insect and Poultry By-Product Meals in Fishmeal-Free Diets

Abstract

This study compared the nutrient-energy retention, digestive function, growth performance, and welfare of rainbow trout (ibw 54 g) fed isoproteic (42%), isolipidic (24%), fishmeal-free diets (CV) over 13 weeks. The diets consisted of plant-protein replacement with graded levels (10, 30, 60%) of protein from poultry by-product (PBM) and black soldier fly H. illucens pupae (BSFM) meals, either singly or in combination. A fishmeal-based diet was also tested (CF). Nitrogen retention improved with moderate or high levels of dietary PBM and BSFM relative to CV (p p p p < 0.05). In conclusion, moderate to high PBM and BSFM inclusions in fishmeal-free diets, either singly or in combination, improved gut function and nutrient retention, resulting in better growth performance and the good welfare of the rainbow trout.

Keywords

• alternative proteins
• digestive function
• immune response
• <i>Hermetia illucens</i>
• nutrient retention
• poultry by-product meal