Dietary Taurine Improves Growth Performance and Intestine Health via the GSH/GSSG Antioxidant System and Nrf2/ARE Signaling Pathway in Weaned Piglets

Early weaning of piglets was prone to increase reactive oxygen species, disrupt the redox balance, decrease antioxidant capacity, cause oxidative stress and intestinal oxidative damage, and lead to diarrhea in piglets. This research aimed to study dietary taurine (Tau) supplementation at a level relieving intestinal oxidative damage in early-weaned piglets. A total of 48 piglets were assigned to four groups of 12 individuals and fed a basal diet with 0.0% Tau (CON), 0.2% Tau (L-Tau), 0.3% Tau (M-Tau), or 0.4% Tau (H-Tau), respectively. The animal experiment lasted 30 days. The final weight, weight gain, average daily gain, and feed conversion rate increased with the increase in dietary Tau (Linear, p < 0.05; Quadratic p < 0.05), while the diarrhea index of piglets decreased with the increase in dietary Tau (Linear, p < 0.05). Serum malondialdehyde, nitric oxide (NO), D-lactose, and oxidized glutathione (GSSG) concentrations decreased with the increase in dietary Tau (Linear, p < 0.05). The O2•− and •OH clearance rate in serum, liver, and jejunum mucosa increased with the increase in dietary Tau (Linear, p < 0.05). Serum superoxide dismutase (SOD) activity, glutathione peroxidase (GPX) activity, catalase (CAT) activity, and peroxidase (POD) activity and total antioxidant capacity increased with the increase in dietary Tau (Linear, p < 0.05). The serum glutathione (GSH) concentration and the ratio of GSH to GSSG increased with the increase in dietary Tau (Linear, p < 0.05). The POD and glutathione synthase activity in the liver and jejunum mucosa increased with the increase in dietary Tau (Linear, p < 0.05). The mRNA abundances of HO-1 and GPX1 in the H-Tau group were higher than that in the L-Tau, M-Tau, and CON groups (p < 0.05). The mRNA abundances of SOD1 and Nrf2 in the M-Tau and H-Tau groups were higher than in the L-Tau and CON groups (p < 0.05). The mRNA abundance of SOD2 in the L-Tau, M-Tau, and H-Tau groups was higher than in the CON group (p < 0.05). The VH and the ratio of VH to CD of jejunum and ileum increased with the increase in dietary Tau (Linear, p < 0.05). The mRNA abundances of occludens 1 and claudin 1 in the H-Tau group were higher than that in the CON, L-Tau, and M-Tau (p < 0.05). The mRNA abundance of occludin in the L-Tau, M-Tau, and H-Tau groups was higher than that in CON (p < 0.05). The abundance of Firmicutes increased with the increase in dietary Tau (Linear, p < 0.05), while Proteobacteria and Spirochaetota decreased with the increase in dietary Tau (Linear, p < 0.05). Collectively, dietary supplementation of 0.3% and 0.4% Tau in feed could significantly improve the growth performance and enhance the antioxidant capacity of piglets.