Chicken liver meal as an effective fishmeal replacement for Litopenaeus vannamei diets: A comprehensive evaluation of growth, non-specific immunity and gut health

This experiment was conducted to evaluate the effect of chicken liver meal (CLM) on growth, protein synthesis, antioxidative functions, non-specific immunity, and gut microbiota community for juvenile Litopenaeus vannamei. CLM was used to replace 10, 20, 40, 60, and 80 % of fishmeal (FM) protein, respectively. Six iso-nitrogenous and iso-lipidic diets were designed (named FM, C10, C20, C40, C60, and C80) and fed to shrimp (initial weight, 0.54 ± 0.01 g) for 8 W. Weight gain (WG) and specific growth rate (SGR) were significantly higher and feed coefficient rate (FCR) significantly lower (P < 0.05) in the C10 and C20 groups compared to the FM group. Protein efficiency rate (PER) and protein deposition rate (PDR) were significantly increased in the C10, C20, and C40 groups (P < 0.05). Whole body crude protein (CP) content was significantly higher in the C20 group (P < 0.05). Total antioxidant capacity (T-AOC), catalase (CAT) and superoxide dismutase (SOD) activities were significantly (P < 0.05) higher in C20, C40, C60 and C80 groups. In serum, acid phosphatase (ACP), alkaline phosphatase (AKP), phenol oxidase (PO) and lysozyme (LZM) activity values were highest in the C20 or C40 groups (P < 0.05). Trypsin (TYS), amylase (AMS), glutamic pyruvic transaminase (GPT) and glutamic oxalic transaminase (GOT) activities were significantly higher in the C10 and C20 groups than in the FM group (P < 0.05). Target of rapamycin (tor), eukaryotic translation initiation factor 4E (eif4e) and 4E-binding protein (4ebp) genes mRNA expression levels in the C10, C20 and C40 groups, as well as eukaryotic translation initiation factor 3 K (eif3k) in the C10 and C20 groups were significantly up-regulated (P < 0.05). The mRNA expression levels of penaiedin 3a (pen 3a), crustin a (cru a), lysozyme (lzm), pro-phenol-oxidase (po), and immune deficiency (imd) in the C40 group were significantly higher than those in FM group (P < 0.05). The Vibrio parahaemolyticus challenge test showed that the cumulative mortality in the C20 and C40 groups was significantly lower than that in the FM group (P < 0.05). In gut microbiota community analysis, the Bacteroidetes abundance was increased, while the Proteobacteria abundance were decreased with the increase of CLM replacement levels. Meanwhile, the Vibrionaceae abundance in each replacement group were all lower than those in the FM group. In conclusion, CLM could replace the FM protein in the diet of L. vannamei up to 80 %.