Effect of replacing a portion of fish meal with unfermented and/or fermented soybean meal on the growth performance, antioxidant and immunity capacity and related gene expression in juvenile Coho Salmon, Oncorhynchus kisutch

Abstract

This study investigated the effect of replacing a portion of fish meal with unfermented and/or fermented soybean meal in juvenile coho salmon (Oncorhynchus kisutch). Four groups of juveniles (initial weight 110.31 ± 3.12 g) in triplicate were fed for 90 days on four different iso‐nitrogen and iso‐lipid diets. The G0 diet comprised 28% fish meal protein (control group). In the other three diets (G1, G2, and G3), 10% of the fish meal protein was replaced with unfermented and/or fermented soybean meal protein. The main results were: Compared with G0, the WGR, SGR, CF; the contents of GLU, TP, ALB, T‐CHO, and T‐AOC, the activities of AKP, CAT, SOD, GST, GSH‐PX, O2·‐CR, OH·‐CR, and GSH and the expressions of SOD, GSH‐PX, GST, CAT, and Nrf2 genes of juvenile coho salmon in G3 were significantly (p < 0.05) increased, However, the FCR, HSI, the content of MDA, and the expressions of TNF‐α and IL‐6 genes of juvenile coho salmon in G3 were significantly (p < 0.05) decreased. There was no significant effect (p > 0.05) of diet on their survival rate (SR). In conclusion, the fermented soybean meal in the juvenile coho salmon diet can replace 10% of the fish meal protein.