Dietary Mannan Oligosaccharide Supplementation During Gestation Alters Milk Composition in Jennies and Improves Growth Performance, Lipid Metabolism, and Gut Microbiota in Dezhou Donkey Foals

Mannan oligosaccharides (MOSs) are used as prebiotic feed additives, but their effects on lactating donkeys and their offspring remain poorly understood. This study evaluated the effects of maternal dietary MOS supplementation on milk composition, foal growth and serum biochemical parameters, and the fecal microbiota of Dezhou donkey foals. We randomly allocated 16 healthy lactating Dezhou donkeys and their foals to the control group (OCON) or the mannan-oligosaccharide supplementation group (OMOS; mannan-oligosaccharides were mixed into concentrate at 0.5 g/kg DM), with 8 replicates per group. The experiment lasted for 60 days. Maternal MOS supplementation did not significantly alter milk fat, protein, lactose, somatic cell count, or milk urea nitrogen, although milk fat and protein were numerically higher in the OMOS group; however, milk somatic cell count was significantly reduced in the OMOS group (p = 0.023). Foals from MOS-supplemented jennies tended to show greater total body weight gain and average daily gain. Serum total cholesterol and LDL-C concentrations were significantly lower, whereas HDL-C was significantly higher, in OMOS foals. MOS supplementation was associated with changes in specific bacterial taxa in the fecal microbiota of donkey foals, rather than a generalized alteration of the overall microbial community. Overall, maternal MOS supplementation was associated with favorable changes in foal growth and cholesterol metabolism, a reduction in milk somatic cell count, and selective alterations in fecal bacterial taxa.