Practical diets for the sustainable production of brown shrimp, Farfantepenaeus californiensis, juveniles in presence of the green macroalga Ulva clathrata as natural food

Abstract

This study evaluated five experimental diets (40 % protein, 11 % lipids): the first diet (FM) was formulated with 10 % fish meal content and no fish oil; the second diet (FO) contained 0.5 % fish oil, while fish meal was totally replaced with poultry by-product meal; the third (DHA) and the fourth (LO) diets were formulated to replace fish oil with 0.5 % microalga oil and 0.5 % linseed oil, respectively; the fifth diet (SLO) used soybean meal and corn gluten as main protein sources, with 0.5 % linseed oil. A conventional, commercial-like diet (Ctrl) included 36 % fish meal and 1.4 % fish oil (36 % protein, 7.5 % lipids). Brown shrimp Farfantepenaeus californiensis juveniles (0.12 g) were stocked into 50-L tanks at ten shrimp tank−1, and eight feeding treatments were applied: shrimp fed Ctrl diet ad libitum (100 % pelleted feed ration: CtrlA); shrimp fed a 50 % ration of Ctrl diet (CtrlB), FM, FO, DHA, LO, or SLO in presence of fresh Ulva offered ad libitum; and, finally, shrimp fed only fresh Ulva (UC). After the 8-week feeding trial, survival was over 87 %; CtrlA, CtrlB, FM, and SLO treatments presented significantly better growth (p < 0.05); CtrlB, FM, and SLO improved significantly (p < 0.05) the feed conversion ratio and protein efficiency ratio by approximately 100 % compared to CtrlA. Results confirm that with a plant-based diet in the presence of live Ulva clathtrata available ad libitum, it is possible to obtain a sustainable shrimp product.