Fishmeal can be replaced with a high proportion of terrestrial protein in the diet of the carnivorous marine teleost (Trachinotus ovatus)

Abstract

In general, over 30% fishmeal (FM) is required in diets for marine teleosts, which limits the sustainable development of aquaculture. Here, seven isonitrogenous (46%) and isolipidic (12%) diets (namely D1-D7) were formulated with three compound proteins (CPro I, CPro II and CPro III), which consisted of terrestrial animal and plant proteins, as substitutes for FM. Diet D1 (control) contained 30% FM, while diets D2-D3, D4-D5 and D6-D7 were formed by replacing 40% and 60%, 40% and 60%, and 60% and 80% FM with CPro I, CPro II, and CPro III, respectively. Juveniles of the carnivorous marine teleost Trachinotus ovatus were fed the seven diets in floating sea cages for 8 weeks. Growth performance including weight gain (WG) and specific growth rate (SGR), serum biochemical indices alkaline phosphatase (AKP) and glutamic pyruvate transaminase (GPT) activities, serum and liver antioxidant indices catalase (CAT) activities and total antioxidant capacity (T-AOC), fish proximate composition, muscle cooking percentage (CP) and textural properties of fish fed diets D2-D7 showed no difference or improved values compared with those of fish fed diet D1, suggesting no negative effects produced with 40–80% replacement of dietary FM by the compound proteins. Significantly higher contents of essential amino acids (EAA), non-essential amino acids (NEAA) and flavour amino acids (FAA) in muscle, as well as higher liver antioxidant capacity were found in fish fed diets D6 (12% FM) or D7 (6% FM) compared with those fed diet D1. The results demonstrated that 40–80% replacement of dietary FM by terrestrial compound proteins is feasible in T. ovatus, moreover 60% or 80% replacement brought a positive influence on antioxidant capacity and nutritional value.