Intestinal Barrier Function and Performance of Broiler Chickens Fed Additional Arginine, Combination of Arginine and Glutamine or an Amino Acid-Based Solution

SIMPLE SUMMARY: There is growing evidence that amino acids can influence intestinal barrier function and inflammation in broiler chickens. Arginine, glutamine, and threonine are regarded as functional amino acids that can help restore gut integrity-related issues under enteric or stress-related conditions. The present study aimed to investigate different combination of arginine, glutamine, and threonine plus a grape extract specifically tailored to improve performance and intestinal functions of broilers. The results showed that tested amino acids were able to improve feed conversion ratio of broilers while alleviating the intestinal inflammation caused by administration of synthetic glucocorticoid through different pathways. There was also indication of changes in intestinal permeability by tested amino acids. The mechanistic understanding of different amino acids and their combinations presents opportunity to optimize intestinal barrier function particularly under stress related conditions. ABSTRACT: Two experiments were conducted to investigate the effect of arginine (Arg); the combination of Arg and glutamine (Gln); as well as an amino acid-based solution (MIX) containing Arg, Gln, threonine (Thr), and grape extract, on performance, intestinal permeability, and expression of selected mechanistic genes. Using 240 male Ross 308 off-sex broiler chickens, four experimental treatments were replicated six times with 10 birds per replicate. The experimental treatments included 5 g/kg Arg, 2.5 g/kg Arg and 2.5 g/kg Gln, and 1 g/kg MIX added to a basal diet as control. In the second study, the four dietary treatments were then given to 24 birds with or without a synthetic glucocorticoid, dexamethasone (DEX), as a gut dysfunction model. Feed conversion ratio was improved by all the supplemented treatments from day 7 to 35 of age (p < 0.001). DEX injections increased (p < 0.001) the intestinal permeability in all treatments, which tended to be reversed by Arg or MIX. Additional Arg, Arg-Gln, and MIX suppressed (p < 0.05) the overexpression of IL-1β generated by DEX. Feeding birds with MIX treatment increased (p < 0.05) expression of SGLT-1 and glutathione synthetase. In conclusion, tested amino acid supplements were effective in improving feed efficiency and restraining intestinal inflammation caused by DEX through IL-1β pathway.