Amelioration of ammonia‐induced oxidative stress, ferroptosis and intestinal damage in <scp> <i>Pelteobagrus fulvidraco</i> </scp> through dietary tea polyphenols

To investigate the impact of tea polyphenols on the health of Pelteobagrus fulvidraco under ammonia stress, a total of 480 juvenile P. fulvidraco were divided into four groups receiving tea polyphenols supplemented diets at 0 mg kg^-1 (C group), 200 mg kg^-1 (L group), 400 mg kg^-1 (M group) and 600 mg kg^-1 (H group) for 56 days. Ammonia stress was applied from days 28 to 56. The results showed that intestinal histological damage was alleviated in the L and M groups under ammonia stress. In the M group, the levels of total antioxidant capacity and Nrf2, HO-1 and Occludin were the highest. Regarding ferroptosis-related genes, DMT1, FTM and FPN1 exhibited their highest expression in the L group, while TF, TFR1, FTL, SLC7A11 and GPX4 showed their highest expression in the M group. FTH demonstrated its highest expression in the H group. Furthermore, the expression of ACSL4 in the L and M groups was significantly lower than that in the C group. Intestinal microbiome analysis revealed enhanced microbial diversity in the tea polyphenol-added groups, accompanied by reduced relative abundance of dominant phylum Fusobacteriota and genus Cetobacterium compared to the C group. These results suggested that dietary supplementation of 200-400 mg kg^-1 tea polyphenols could alleviate ammonia-induced intestinal ferroptosis and histological damage, as well as protect intestinal health by regulating the compositional structure and diversity of the intestinal microflora. Specifically, the 400 mg kg^-1 dose exerted the most comprehensive protective effects. This study provides mechanistic insights into the development of tea polyphenol-based anti-ammonia feed additives for P. fulvidraco aquaculture.