Lactobacillus spp. fermented soybean meal partially substitution to fish meal enhances innate immune responses and nutrient digestibility of white shrimp (Litopenaeus vannamei) fed diet with low fish meal

To accomplish the goal of sustainable aquaculture, substitution of fish meal (FM) with available and effective alternative ingredients is necessary. The present study evaluated the effects of fermented soybean meal (FSBM) substituted to FM on growth, innate immune responses, nutrient digestibility, and morphological changes in hepatopancreas of white shrimp Litopenaeus vannamei, fed a low FM diet. The FM protein was replaced by FSBM at 0%, 25% (25% FSBM), 50% (50% FSBM), 75% (75% FSBM), and 100% (100% FSBM) in the control diet (including 15% FM). Experimental diets were each fed in triplicates to juvenile shrimp with initial weight of 5.53 g in a closed recirculation system for eight weeks. Shrimp fed different diets exhibited similar (p > 0.05) growth performance and morphology in hepatopancreas. Shrimp fed the 75% FSBM diet had higher total hemocyte count than other dietary groups. Shrimp fed the 75% FSBM diet exhibited the highest phenoloxidase (PO) activity, followed by shrimp fed 50% FSBM and 100% FSBM diets, and lowest in shrimp fed the control and 25% FSBM diets. Apparent digestibility of dry matter, protein and lipid showed the highest performance in shrimp fed the 75% FSBM diet compared with other dietary treatments. Results indicate that FSBM can completely replace fish meal protein without any negative effects on growth and morphology in hepatopancreas. The adequate replacement levels is suggested at 75% to improve innate immune responses and nutrient digestibility for white shrimp.