Dietary taurine supplementation to a plant protein source-based diet improved the growth and intestinal immune function of young grass carp (Ctenopharyngodon idella)

The effects of taurine supplementation on the growth and intestinal immune function in young grass carp (Ctenopharyngodon idella) were investigated in this study. A total of 540 fish (initial average weights of 255.74 +/- 0.65 g) were fed one fish-meal diet and five all-plant protein source-based diets with graded levels of taurine (0 to 1.98g/kg diet) for 60 days, and then challenged with Aeromonas hydrophila for 14 days. First, the results showed that the taurine supplementation improved growth (PWG, TGC, FI and FE), enteritis resistance, intestinal antimicrobial compounds (LZ, ACP, C3, C4, IgM, hepcidin, LEAP-2A, LEAP-2B, beta-defensin-1 and MUC2) and attenuated intestinal inflammation in young grass carp under the all-plant protein sourcebased diet. Second, the taurine supplementation attenuated intestinal inflammation partially referring to nuclear factor kappa B (NF-kappa B) and target of rapamycin ( TOR) signallings. Finally, under the all-plant protein source-based diet, the comparable level of taurine supplementation based on growth and ability against enteritis relative to fishmeal diet was established as 0.50 g/kg diet, and the optimal levels of taurine supplementation based on thermal-unit growth coefficient (TGC), ability against enteritis and acid phosphatase (ACP) activity were established as 0.97, 1.08 and 1.21 g/kg diet, respectively.