Abstract
<jats:p>Dietary β-mannan acts as an anti-nutritional factor by eliciting intestinal immune responses that divert dietary energy, thereby compromising productive performance. This study investigated the effects of β-mannanase supplementation in diets with varying energy levels on the growth performance and intestinal health of weaned piglets. 150 weaned piglets were randomly assigned into 3 groups: (1) Control group (basal diet), (2) CEM group (basal diet + 0.015% β-mannanase), (3) CM group (reduced-energy diet + 0.015% β-mannanase). During the experiment, body weights were measured on d 7, 14 and 45, average daily feed intake (ADFI) was calculated daily. Fecal and blood samples were collected on d 7 and d 14. The research indicated that the CEM group had a higher final body weight on d 45 (P = 0.05) and increased average daily gain (ADG) from d 15 to d 45 (P ＜ 0.05) compared to the control group. The CM group exhibited a higher ADFI from d 0 to d 7 (P ＜ 0.01). β-mannanase supplementation reduced diarrhea incidence in weaned piglets throughout the study. Regarding intestinal barrier and inflammation, dietary β-mannanase supplementation increased the expression of Zonula Occludens -1 (ZO-1), Occludin, and Transforming growth factor (TGF)-β, while decreasing the levels of β-defensin 1 (pBD-1), Porcine Myeloid Antimicrobial Peptide (PMAP) - 37, Lipocalcin-2, interleukin (IL)-1β, and IL-10 compared with the control group (P ＜ 0.05). Fecal calprotectin, lipocalcin-2 and IL-1β concentrations were also down-regulated in both the CEM and CM groups (P ＜ 0.05). Meanwhile, compared with the control group, the relative abundance of Lactobacillus was increased only in the CM group on d 14 (P ＜ 0.05), whereas Escherichia coli was decreased following β-mannanase supplemention on d 14. In addition, β-mannanase enhanced antioxidant capacity by increasing Glutathione peroxidase (GSH-PX) and Superoxide dismutase (T-SOD) activities while decreasing Malonaldehyde (MDA) level (P ＜ 0.05). Dietary β-mannanase attenuates β-mannan-induced immune activation, mitigates diarrhea incidence and enhances growth performance in piglets. Crucially, supplementation of β-mannanase in reduced-energy diets maintains growth performance and intestinal homeostasis equivalent to control diets, demonstrating its dual capacity to reduce energy loss while preserving intestinal health integrity.</jats:p>