Effects of xylooligosaccharide supplementation on methane emissions, rumen microbiome, and serum metabolome in lactating Jersey cows

Xylooligosaccharides (XOS) are recognized as effective prebiotics that can mitigate methane (CH4) emissions. However, the specific relationship between the effects of XOS on CH4 emissions and alterations in the ruminal microbiota and their metabolites remains unclear. To investigate the relationship between XOS and CH4 emissions, 48 Jersey cows were randomly divided into two groups: the XOS group (group T) and the control group (group C). Group T received 25 g/d of XOS, while group C received 0 g/d of XOS added to the basal diet. Three randomly selected cows from each group, exhibiting consistent milk production and lactation stage, were analyzed for CH4 emissions detection, 16S rRNA sequencing, and untargeted metabolomics analysis. The addition of XOS significantly reduced CH4 emissions and increased both the number of observed species and the abundance-based coverage estimator (ACE) index of ruminal microbiota compared to group C. Sixteen differential metabolites were identified between the two groups; these differential metabolites were correlated with microbiota, including Chloroflexi, Acidobacteriota, and Succiniclasticum. The study suggests that XOS may regulate ruminant CH4 emissions by influencing the microbiota, thereby providing a rationale for CH4 control.