Xylo-oligosaccharides supplementation as prebiotic to fattening Hu lambs: effects on growth, nutrient digestibility, and rumen bacterial community

Objective: Supplementation with xylo-oligosaccharides (XOS) has been shown to selectively stimulate the growth of beneficial intestinal bacteria and improve gut health and function in monogastric animals such as chickens and pigs.However, the effect of XOS in fattening Hu lambs have not been fully elucidated.Therefore, this study aimed to evaluate the effects of dietary XOS supplementation on growth performance, nutrient digestibility, rumen fermentation parameters, and the ruminal bacterial community in fattening Hu lambs.Methods: A total of 32 fattening lambs with an average body weight (BW) of 20.39±0.35kg (3 mo of age) were randomly assigned to either a control diet without the XOS-containing product (Control, n=16) or a diet supplemented with the commercial XOS-containing product at 6 g/kg DM (corresponding to ≥1.5 g XOS/kg dietary DM;XOS, n=16).Body weight was recorded on d 0, 21, 42 and 63.At the end of the experiment, rumen fluid samples from randomly selected lambs were collected for VFA analysis and rRNA gene sequencing.Results: Dietary XOS supplementation increased final body weight (BW) and dry matter intake (DMI), while average daily gain (ADG) tended to be greater when evaluated over the entire 63d experimental period.Repeated-measures analysis indicated an overall treatment effect on ADG.Additionally, XOS supplementation increased NDF digestibility and the amount of digested NDF.At the time of rumen sampling, total volatile fatty acid (VFA) concentration and the molar proportion of butyrate were greater, whereas the molar proportions of isobutyrate and isovalerate were lower in XOS-supplemented lambs than in control lambs.In addition, XOS supplementation decreased the Shannon and Simpson diversity indices without affecting ACE or Chao1 richness indices and increased the relative abundance of Bacteroidetes.Conclusion: Dietary XOS supplementation was associated with greater DMI, improved NDF A c c e p t e d A r t i c l e utilization, and altered ruminal VFA profiles and bacterial community composition in finishing Hu lambs.These responses were accompanied by greater final BW, suggesting that dietary XOS supplementation may have potential as a nutritional strategy for finishing lambs.