Dietary grape pomace ameliorates intestinal damage and oxidative stress by modulating MAPK-Nrf2/ARE pathways in coccidia-challenged broilers (Gallus gallus).

Grape pomace (GP) is an agricultural byproduct rich in bioactive compounds with antimicrobial, antioxidant, and immunomodulatory properties that have proven to have strong antioxidant and immunomodulatory properties in chickens. As a part of a defense mechanism, coccidiosis initiates oxidative bursts, generating large amounts of free radical species that negatively affect the gut health of chickens. This study aimed to evaluate the effect of dietary inclusion of GP in broilers infected with coccidiosis on physiological and molecular markers of gut health, immune response, and oxidative status. A total of 120 male broiler chickens were randomly assigned to one of the four treatments. The four treatment groups were i) non-challenged control without any dietary feed additives (NCC), ii) challenged control without any dietary feed additives (CC), iii) CC with 0.5 % dietary inclusion of concord grape pomace (0.5GP), and iv) CC with 0.75 % dietary inclusion of concord grape pomace (0.75GP). On d 14, broilers grouped in CC, 0.5GP, and 0.75GP were orally inoculated with 20 × doses of commercial live coccidiosis vaccine to induce coccidiosis. Results indicated that 0.75 % inclusion of GP reduced the occurrence and severity of the intestinal lesions associated with Eimeria at d 20 (P<0.05). The inclusion of either 0.5 or 0.75 % of GP improved the intestinal histomorphology in all three sections of the small intestine during the acute and recovery phases of coccidial infection (P<0.05). At d 20, 0.75GP tended to maintain the same level of IL-1β as that of NCC and downregulated the expression of IL-10 (P<0.1). Additionally, during the recovery phase, the CD8+ T-cell population was lower in the 0.75GP group compared to CC and 0.5GP (P=0.059). At d 20, the MAPK-Nrf2/ARE pathway was activated due to oxidative burst by coccidial challenge; however, 0.75 % GP inclusion was able to inactivate the path (P<0.05). These findings suggest that grape pomace possesses the potential as a sustainable feed additive to improve gut health, immune response, and oxidative stability in broilers infected with coccidiosis.