Terminalia Chebula Extract Replacing Zinc Oxide Enhances Antioxidant and Anti-Inflammatory Capabilities, Improves Growth Performance, and Promotes Intestinal Health in Weaned Piglets

This study aimed to assess the effects of substituting zinc oxide with terminalia chebula extract (TCE) on growth performance, antioxidant capacity, immune function, and intestinal health in weaned pigs. Initially, 72 weaned Duroc × Landrace × Large White piglets, 28 days old with an initial weight of 7.43 ± 0.14 kg, equally divided by gender, were randomly assigned into three groups, with six replicates and four piglets per replicate. They were fed a basal diet (CON group), a diet containing 2 g/kg zinc oxide (ZnO group), or 2 g/kg TCE (TCE group) for a duration of 28 days. Subsequently, to further confirm the most appropriate levels of TCE in piglets, 96 piglets of the same breeds and age, with an initial weight of 7.42 ± 0.12 kg, also equally divided by gender, were randomly assigned into four groups, each with six replicates and four piglets per replicate, and fed a basal diet (CON group), or diets supplemented with 1 g/kg TCE (LTCE group), 2 g/kg TCE (MTCE group), or 4 g/kg TCE (HTCE group) for a duration of 28 days. The results demonstrated that both TCE and ZnO reduced diarrhea rates (<i>p</i> = 0.001) and enhanced average daily gain (ADG) (<i>p</i> = 0.014) compared to the control group. TCE at 1 g/kg and 4 g/kg reduced the feed to gain ratio (<i>p</i> = 0.050). Dietary supplementing with TCE and ZnO increased serum total antioxidant capacity (T-AOC) (<i>p</i> = 0.020). Various doses of TCE also increased jejunal IgA (<i>p</i> = 0.000) levels and IL-10 expression (<i>p</i> = 0.004), and decreased the levels of TNF-α in both serum (<i>p</i> = 0.043) and jejunal mucosa (<i>p</i> = 0.000). Notably, TCE reduced the crypt depth (CD) of the duodenal (<i>p</i> = 0.007) and increased the villus height (VH) of the ileal (<i>p</i> = 0.045), and with increased dosage, there was a rise in the villus height to crypt depth ratio (VH:CD) in the duodenum (<i>p</i> = 0.000) and jejunum (<i>p</i> = 0.001). Higher abundances of <i>Lactobacillaceae</i> (<i>p</i> = 0.000) and lower levels of <i>Streptococcaceae</i> (<i>p</i> = 0.000) and <i>Peptostreptococcaceae</i> (<i>p</i> = 0.035) in cecal contents were fed the ZnO and TCE pigs compared with CON pigs. Therefore, TCE was firstly presented as being able to replace zinc oxide, improve intestinal morphology, and enhance antioxidant and immune functions, thus safeguarding intestinal mucosal health and promoting piglet growth.