Dietary D-Ribose Supplementation in Sheep: Implications on Rumen, Fecal Microbiota, and Metabolic Function

The objective of this study was to investigate the effects of dietary D-ribose supplementation on the microbial diversity, community composition, and metabolic function of the rumen and fecal microbiota in Hu sheep. Eighteen sheep with similar body weights (20.47 ± 0.58 kg) were selected and randomly divided into two groups, with nine sheep in each group. One group was fed a basal diet (Control), while the other group was supplemented with 300 mg kg^-1 of D-ribose in addition to the basal diet (D-Ribose). The results showed that D-ribose supplementation had no significant effect on the richness, diversity, or evenness of the rumen and fecal microbiota (<i>p</i> > 0.05). D-ribose supplementation lowered the relative abundance of Cyanobacteria in the rumen while increasing that of <i>Herbivorax</i> and <i>Faecalibacterium</i> (<i>p</i> < 0.05). In feces, it decreased the relative abundances of Verrucomicrobia, <i>Candidatus</i> Saccharibacteria, <i>Bifidobacterium</i>, and <i>Caproiciproducens</i>, while increasing that of <i>Lawsonibacter</i> and <i>Massilioclostridium</i> (<i>p</i> < 0.05). Non-metric multidimensional scaling (NMDS) analysis of the rumen microbiota revealed a significant overlap between the Control and D-Ribose groups, and analysis of similarities (ANOSIM) showed no significant differences between the two groups (R = 0.079, <i>p</i> = 0.115). In contrast, NMDS analysis of the fecal microbiota showed partial overlap between the two groups, and ANOSIM indicated a significant difference between the Control and D-Ribose groups (R = 0.203, <i>p</i> = 0.017). Dietary D-ribose supplementation had no significant effect on any metabolic function with relative abundance greater than 1% in both the rumen and fecal microbiota (<i>p</i> > 0.05). The results indicated that dietary D-ribose supplementation did not affect the microbial diversity and metabolic function of the rumen and fecal microbiota but altered the relative abundances of certain bacterial genera. This study provides a perspective on rumen and fecal microbiota to more comprehensively evaluate the effects of dietary D-ribose supplementation on ruminants and offers data support for the application of D-ribose in ruminant production.