Dietary Mannan Oligosaccharides Enhance Lactational Performance, Nutrient Metabolism, Plasma Metabolomics, and Gut Microbiota in Dezhou Donkeys

This study investigated the effects of dietary mannan oligosaccharide (MOS) supplementation on growth performance, serum biochemistry, metabolomic profiles, and fecal microbiota in lactating Dezhou donkeys. Sixteen healthy jennies and their foals were randomly allocated to a control group (MCON), a group receiving no MOS, or an MOS-supplemented group (MMO; 0.5 g/kg diet) for 60 days. Compared with the MCON group, the MMO group showed a mitigation of lactational weight reduction, improved serum protein profiles, and favorable modulation of lipid metabolism. Furthermore, serum metabolomic analysis revealed 102 differentially abundant metabolites, which were enriched in 17 KEGG pathways involved in energy metabolism, bile secretion, and anti-inflammatory signaling. Key metabolites such as L-4-Chlorotryptophan, Gly-Trp, and cholylthreonine indicated enhanced nutrient metabolism and gut barrier function. Moreover, MOS supplementation significantly increased alpha diversity of the gut microbiota, altered community composition, and promoted the abundance of beneficial genera, including Clostridium and Bacteroides. Collectively, these results demonstrate that MOS supplementation improves metabolic health, modulates immune and antioxidant responses, and fosters a beneficial gut microbial ecosystem in lactating donkeys, suggesting its potential as an effective prebiotic in equine nutrition.