Metabolome Analysis Reveals Potential Mechanisms of Mannan Oligosaccharides to Improve Health, Growth Performance, and Fatty Acid Deposition in IHu/I Lambs

The effect of mannan oligosaccharides (MOS) on health, growth performance, fatty acids deposition, serum, and urine metabolites, as well as the correlation between differential metabolites and other indexes, were investigated in Hu lambs. In total, 30 seven-day-old Hu male lambs were fed a milk replacer with or without 0.2% MOS (15 lambs in each). The lambs were placed on this diet until they were 28 days old. MOS significantly increased the apparent digestibility of organic matter (OM), crude protein (CP), ether extract (EE), calcium (Ca) and phosphorus (P), and unsaturated fatty acid (UFA) proportion, and decreased the diarrhea rate and saturated fatty acid (SFA) proportion in lambs (p < 0.05). MOS upregulated 20 metabolites in serum and 1 in urine and downregulated 11 metabolites in serum and 2 in urine (p < 0.05). Most of these metabolites comprised glycerophosphoethanolamines and glycerophosphocholines, which are significantly correlated with nutrient digestibility and fatty acid composition (p < 0.05). Overall, our results suggest that MOS benefited the health, nutrient utilization, and fatty acid profiles in Hu lambs via glycerolipid and glycerophospholipid metabolism pathways.