Optimal dietary protein level improved growth, disease resistance, intestinal immune and physical barrier function of young grass carp (Ctenopharyngodon idella)

This study investigated the effects of dietary proteins on the growth, disease resistance, intestinal immune and physical barrier functions of young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp (264.11 ± 0.76 g) were fed six diets containing graded levels of protein (143.1, 176.7, 217.2, 257.5, 292.2 and 322.8 g digestible protein kg−1 diet) for 8 weeks. After the growth trial, fish were challenged with Aeromonas hydrophila and mortalities were recorded for 14 days. The results indicated that optimal dietary protein levels: increased the production of antibacterial components, up-regulated anti-inflammatory cytokines, inhibitor of κBα, target of rapamycin and ribosomal protein S6 kinases 1 mRNA levels, whereas down-regulated pro-inflammatory cytokines, nuclear factor kappa B (NF-κB) P65, NF-κB P52, c-Rel, IκB kinase β, IκB kinase γ and eIF4E-binding proteins 2 mRNA levels in three intestinal segments of young grass carp (P < 0.05), suggesting that optimal dietary protein level could enhance fish intestinal immune barrier function; up-regulated the mRNA levels of tight junction complexes, B-cell lymphoma protein-2, inhibitor of apoptosis proteins, myeloid cell leukemia-1 and NF-E2-related factor 2, and increased the activities and mRNA levels of antioxidant enzymes, whereas down-regulated myosin light chain kinase, cysteinyl aspartic acid-protease 2, 3, 7, 8, 9, fatty acid synthetase ligand, apoptotic protease activating factor-...
Source: Fish and Shellfish Immunology - Category: Biology Source Type: research