Effects of Acalypha australis L. Extract on Growth Performance, Antioxidant Capacity and Intestinal Microbial Composition in Weaned Piglets

The objective of this study was to investigate the effects of Acalypha australis L. extract (ALE) on the growth performance and intestinal health in piglets. A total of 24 weaned piglets were randomly allocated to three groups: the control group (CON), which was fed a basal diet, and the ALE0.5 and ALE1.0 groups, which were fed the basal diet supplemented with 0.5 and 1.0 g/kg of ALE, respectively. The measured variables included growth performance, digestive enzyme activity, intestinal morphology, antioxidant capacity, and intestinal microbiota and metabolites. The results showed that, compared to the CON group, supplementation of 1.0 g/kg ALE in the diets of weaned piglets significantly increased the ratio of gain to feed from 15 to 21 days (p < 0.05), decreased the diarrhea rate from Days 15 to 21 and Days 0 to 21 (p < 0.05), and increased the activities of pancreatic α-amylase, lipase, trypsin, and chymotrypsin, as well as duodenal α-amylase, lipase, and trypsin, and jejunal maltase and sucrase (p < 0.05). Additionally, supplementation of 1.0 g/kg ALE in the diet significantly improved the intestinal morphology of the duodenum and jejunum, as well as the expression of intestinal barrier-related genes in the small intestine (p < 0.05). Moreover, it significantly increased serum glutathione peroxidase activity and jejunal and ileal superoxide dismutase activities (p < 0.05), and also significantly increased the colonic propionic acid concentration of piglets (p < 0.05). The ALE supplementation increased the abundance of the colonic marker bacteria Collinsella in the piglets and influenced pathways related to amino acid metabolism, carbohydrate metabolism, and lipid metabolism. ALE can serve as a potential natural feed additive to regulate the structure of intestinal microbiota and metabolic pathways, enhance antioxidant capacity, improve intestinal health, reduce diarrhea incidence, and ultimately promote the growth performance of piglets.