Intestinal health of broiler chickens fed red seaweed (Chondracanthus chamissoi) under dexamethasone-induced stress.

Functional feed additives such as seaweed are increasingly studied as alternatives to antibiotics to mitigate intestinal health challenges in poultry. In this study, Cobb500 broilers received in-feed dexamethasone (DEX) to induce stress and gut integrity impairment from day 14 to 21 post hatching. Seaweed (Chondracanthus chamissoi) was supplemented to evaluate its potential to mitigate DEX-induced changes in performance, intestinal permeability, and jejunal gene expression. In phase 1, a total of 384 broiler chicks were assigned to three dietary treatments (0%, 1%, or 2% seaweed) with 16 replicate cages of eight birds each from day 0 to 14. During phase 2, from d 14 to 21, 336 birds on the same diets from Phase 1 were reallocated to a 3 × 2 factorial arrangement with or without DEX challenge. Intestinal permeability was assessed using fluorescein isothiocyanate-dextran (FITC-D). Data were analyzed using the MIXED procedure in SAS, and factorial analysis of covariance (ANCOVA) was conducted for Phase 2. Orthogonal polynomial contrasts analysis was done to examine linear and quadratic trends associated with seaweed inclusion. Seaweed tended to linearly increase feed intake (P = 0.097) and improved the gain-to-feed ratio (P < 0.05) in phase 1. In phase 2, DEX increased (P < 0.0001) serum FITC-D concentration and reduced most of the physiological response variables. Seaweed tended to reduce serum FITC-D (P = 0.08), but did not influence intestinal morphology and growth performance variables. Seaweed reduced nutrient digestibility and elevated the mRNA expression of Zona occludens 1, Superoxide Dismutase 1, Glutathione Peroxidase-1 and glucose transporters. In conclusion, seaweed can potentially reduce oxidative stress in broiler chickens, but its effect is dose dependent.