Effects of terrestrial lipid blend on the growth performance, body composition, nonspecific immunity, antioxidant status and stress resistance when the dietary n‐3 long‐chain polyunsaturated fatty acids requirements are met in juvenile Japanese sea bass ( Lateolabrax japonicus )

Abstract

This study was conducted to investigate the effects of replacing dietary lipid source FO with a terrestrial lipid blend (LB) on the growth performance, body composition and immunity of juvenile Japanese sea bass when the dietary n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) requirements are met (Lateolabrax japonicus). Two types of experimental diets were formulated with the total FO (the control) or the LB (linseed oil and lard = 1:1). A 56-day feeding trial was conducted in floating cages with three replicates for each treatment. The results indicated that a significantly higher specific growth rate (SGR) and feed efficiency ratio (FER) occurred in fish that were fed the LB diet compared with the control group (p < 0.05). There was no significant difference in the survival rate, body composition or body indicates between the groups (p > 0.05). The respiratory burst, alternative complement pathway activity, lysozyme activity, cytokine genes expression and air exposure test results indicated that the replacement of FO with LB did not significantly affect the nonspecific immunity or stress resistance (p > 0.05). The serum antioxidant enzyme activities and liver tissue antioxidant-related gene expression were significantly higher in the control group than in the other group (p < 0.05). Therefore, the terrestrial lipid blends from linseed and lard (1:1) could be used as an alternative for dietary fish oil without compromising the growth performance, nonspecific immunity and resistance to stress in juvenile Japanese sea bass.