Dietary Supplementation of Protease and/or Amylase Improves Growth Performance, Digestive Function, and Intestinal Health of Weaned Piglets

A total of 96 26-day-old weaned piglets were randomly assigned to four groups with three replicates per group: (1) CON group (basal diet), (2) PRS group (protease supplementation), (3) AMS group (amylase supplementation), and (4) combined protease and amylase group (PAS group) (protease and amylase supplementation). Compared to the CON group, AMS group reduced feed-to-gain ratio (p < 0.05). Additionally, all treatments increased ether extract digestibility (p < 0.05). The PRS and AMS groups reduced serum urea nitrogen level (p < 0.01). PAS group increased total protein, and decreased total cholesterol (p < 0.05). PRS and/or AMS supplementation increased serum glutathione peroxidase. IgM and IgG were higher in the AMS group. Furthermore, levels of D-Lactate and diamine oxidase were reduced (p < 0.05). PRS group exhibited increased fecal acetic acid and valeric acid levels (p < 0.05). Microbiota analysis showed that PRS or/and AMS supplementation enriched bacteria, including Anaerovoracaceae and Blautia. Metabolomics analysis revealed that health-promoting differential metabolites, including S-nitrosoglutathione and kynurenic acid, were further enriched, indicating enhanced immune regulation and intestinal homeostasis. Taken together, PRS or/and AMS supplementation can effectively promote nutrient digestion, intestinal microbiota structure and metabolism, and enhance intestinal barrier, thereby improving growth performance in weaned piglets.