Journal of Aquaculture Research & Development

Abstract

Blue Mussel Protein Concentrate Versus Prime Fish Meal Protein as a Dietary Attractant for Turbot (Psetta maxima L.) Given Rapeseed Protein-based Diets

Nagel F, Appel T, Rohde C, Kroeckel S and Schulz C

A feeding experiment was conducted to test the attractant potential of a processed protein concentrate of the blue mussel (BMPC) as replacer for fish meal (FM) protein in rapeseed protein concentrate (RPC)-based diets for turbot. Triplicate fish groups received isonitrogenous and isoenergetic diets with a 50% or 75% replacement of FM protein by a RPC (RPC 50, RPC 75), and further FM protein substitution with 0, 2, 4 or 8% of BMPC. The application of RPC 50/0 provided no significant impact on fish performance compared to FM-reference diet, while daily feed intake (DFI), specific growth rate (SGR) and feed conversion were significantly impaired when fish fed with RPC 75/0 (P<0.05). Incorporation of BMPC failed to significantly improve DFI, SGR and FCR in RPC 50 and RPC 75 treatments (P>0.05). Protein efficiency ratio and protein productive values remained unaffected among all treatments (P>0.05). Excepting crude ash content, no changes in crude protein, crude lipid, dry matter and energy content were obtained. Hepatosomatic index tended to increased (P>0.05) in accordance with slightly hypertrophic hepatocytes of fish fed diets with a BMPC incorporation of 40-80 g kg-1. Neither inflammatory nor degenerative alterations were detected in the intestine. In summary, we demonstrated that BMPC failed to stimulate the feed intake of turbot when dietary FM protein was substituted consecutively, but it was found to maintain performance level of turbot within the test diet groups. This indicates nutritional properties of BMPC comparable to prime FM protein, functional to further reduce the FM protein content in aquafeeds for carnivorous fish.