This study evaluated the effects of dietary selenium-enriched Bacillus subtilis (HBS) supplementation on laying performance, egg quality, and responses to lipopolysaccharide (LPS) challenge. A total of 120 Jinghong-1 laying hens received a basal or HBS-supplemented diet for 12 weeks. Subsequently, hens within each dietary replicate were allocated to phosphate-buffered saline (PBS)- or LPS-injected subgroups, and one hen per subgroup was sampled 12 h after injection, yielding six sampled hens per treatment combination. HBS supplementation reduced the feed-to-egg ratio (1.96 vs. 2.15, p = 0.023) and increased albumen height (7.17 vs. 6.60 mm, p = 0.003) and Haugh unit (83.01 vs. 78.65, p = 0.001). Compared with LPS, HBS+LPS showed lower serum IL-1β concentrations, higher CAT and T-SOD activities, greater jejunal villus height and villus height-to-crypt depth ratio, and higher expression of selected antioxidant- and tight-junction-related genes. Jejunal cytokine responses varied among genes. No significant differences in the measured cecal alpha-diversity indices were detected, whereas exploratory LEfSe analysis identified several treatment-associated taxa. Cecal butyrate concentration was higher in HBS than in CON, with no significant difference between HBS+LPS and LPS. Collectively, these findings indicate that HBS supplementation improved feed utilization and albumen quality and was associated with changes in selected antioxidant, inflammatory, and intestinal responses following LPS challenge. The contributions of selenium and B. subtilis could not be distinguished.

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.