Growth, integrity, and consumer acceptance of largemouth bass, Micropterus salmoides (Lacépède, 1802), fed marine resource-free diets

Abstract

Largemouth bass (LMB) were fed diets developed to substitute fishmeal (FM) using a blend of alternative proteins. Diets included a FM control (FMC), two FM-free formulæ (FMF), one of which (FFF) was formulated using an algal oil replacing fish oil (FO) and, for comparative purposes, a commercial LMB feed (COM). Fish (densities of 3.11±0.29 kg m-1) were arbitrarily distributed into one of eight tanks configured as a recirculating system (RAS; 28.3±0.76 oC; DO2: 7.7±1.19 mg L-1) and tanks randomly assigned to one of the four treatments (i.e. each treatment was tested in duplicate). Animals were fed 3x daily to apparent satiation and group weighed every 3 weeks for 18 weeks. No differences were observed in feed consumption between groups (P >0.05) but LMB fed the COM diet were heavier (P< 0.05) than fish fed the FMF and FFF feeds. In efforts to verify whether fish fed the FM/FO-free were authentic, samples were assessed by stable isotope ratio mass spectrometry. δ15N fish muscle isotope values at trial end were indicative of dietary FM substitution. A preliminary blind taste trial undertaken using fish from the FFF and COM diets did not differentiate between treatments (P > 0.05). Results from the present study show that, with prudent dietary control, complete replacement of FM/FO in LMB diets is attainable and verifiable, without compromising growth performance or consumer acceptance of the final product.