Effects of Dietary Paramylon on Nutrient Digestion and Absorption and Intestinal Health of Weaned Piglets

Weaning stress frequently compromises intestinal integrity and nutrient absorption in piglets and induces structural perturbations in the gut microbiota. This study investigated the effects of dietary Paramylon, a linear β-1,3-glucan from <i>Euglena gracilis</i>, on growth and intestinal function. A total of 32 healthy, 21-day-old weaned piglets (male, castrated, Duroc × Landrace × Yorkshire) were randomly allocated to four groups: control, 0.025%, 0.05%, and 0.1% Paramylon (8 pigs/group). The results showed that 0.05% dietary Paramylon quadratically increased average daily gain and feed intake (<i>p</i> < 0.05). Serum TC content significantly increased, while the serum urea level significantly decreased (<i>p</i> < 0.05). This optimal dose was used for mechanistic exploration. Dietary 0.05% Paramylon notably enhanced ileal morphology, increasing the villus height to crypt depth ratio (<i>p</i> < 0.01) and significantly improving apparent nutrient digestibility and ileal β-amylase activity (<i>p</i> < 0.05). The expression levels of <i>SLC7A1</i> and <i>GLUT2</i> in ileum tissues were significantly upregulated (<i>p</i> < 0.05). The expression level of <i>SLC7A7</i> in the liver was also increased (<i>p</i> < 0.05). This nutrient transport-promoting effect was further confirmed in IPEC-J2 cells, which manifested because 10 ng/mL of pure Paramylon significantly upregulated the gene expressions of <i>SLC38A2</i>, <i>EAAT3</i>, <i>PEPT1</i>, and <i>GLUT2</i> (<i>p</i> < 0.05). KEGG enrichment analysis on the ileum indicated that differentially abundant metabolites were enriched in amino acid-related metabolic pathways. Furthermore, the 16s sequencing results revealed that <i>Romboutsia</i> was significantly enriched in the Paramylon group. In conclusion, Paramylon, as an effective dietary supplement, helps promote nutrient digestion and absorption in weaned piglets and contributes to maintaining intestinal health.