Tannic acid extracted from gallnut improves intestinal health with regulation of redox homeostasis and gut microbiota of weaned piglets

The objective of this study is to evaluate the effects of tannic acid (TA) derived from gallnut supplementation on growth performance and health status of weaned piglets. A total of 432 weanling piglets (7.05 ± 1.05 kg) were randomly allocated into 4 treatment groups with 6 replicates of 18 pigs/pen. Piglets were fed either a basal diet (CON), or basal diets supplemented with 1.5 kg/t TA, 3.0 kg/t TA, or 1.8 kg/t zinc oxide (ZnO) for 21 days. The results showed that, compared to the CON, dietary TA supplementation did not affect (p > 0.05) growth performance and serum biochemistry of weaned piglets. However, 3.0 kg/t TA had higher SOD, GPX, and CAT activities and a lower MDA concentration in the jejunum than those of the CON or the ZnO group. Meanwhile, 3.0 kg/t TA increased (p < 0.05) villus height and villus height/crypt depth, and decreased (p < 0.05) crypt depth in the small intestine. Dietary TA also downregulated (p < 0.05) IL-1β and TNF-α expression in jejunum. Furthermore, 3.0 kg/t TA reduced (p < 0.05) the abundance of Candidatus Brocadia and Escherichia-Shigella in cecal digesta. Notably, both Candidatus Brocadia and Escherichia-Shigella had a negative correlation with antioxidant enzymes activities (R < −0.60, p < 0.01), but Escherichia-Shigella was positively correlated with MDA concentrations (R = 0.44, p < 0.05) in the jejunum. In conclusion, compared to the CON, 3.0 kg/t TA supplementation improved the gut health status of weaned piglets, potentially by regulating redox homeostasis and gut microbiota.