Effect of l-theanine on growth performance, intestinal development and health, and peptide and amino acid transporters expression of broilers

BACKGROUND l-Theanine has multiple beneficial biological activities. However, there is little information about the use of l-theanine in broiler production. Therefore, this study investigated the effect of l-theanine on growth performance, intestinal development and health, and the mRNA levels of intestinal peptide and amino acid (AA) transporters of broilers. RESULTS Body weight and average daily gain were increased by l-theanine, whereas feed to gain ratio was decreased (quadratic, P < 0.05). Notably, the relative weight of duodenum, jejunum and ileum, villus height, villus height to crypt depth ratio, the jejunal activities of glutathione peroxidase, total antioxidant capacity, catalase and total superoxide dismutase were increased linearly and/or quadratically by l-theanine (P < 0.05), whereas crypt depth, serum d-lactic acid, and jejunal protein carbonyls and malondialdehyde content were decreased linearly and/or quadratically (P < 0.05). Moreover, l-theanine enhanced the jejunal mRNA levels of occludin, claudin-1, E-cadherin, zona occludens-1, di- and tripeptide transporter, excitatory AA transporter 3, Na+-independent cationic AA transporter 1, Na+-independent cationic and zwitterionic AA transporter, Na+- and Cl--dependent neutral and cationic AA transporter, Na+-independent cationic and Na+-dependent neutral AA transporter (y+LAT) 1, y+LAT2, Na+-independent branched-chain and aromatic AA transporter, and heavy chain corresponding to the b degrees(,+) transport system (linear and/or quadratic, P < 0.05). CONCLUSIONS l-Theanine beneficially affected the growth performance of broilers by improving intestinal development and health, and the intestinal mRNA levels of AA and peptide transporters. Therefore, l-theanine has the potential to be a promising feed additive for broilers. (c) 2020 Society of Chemical Industry