摘要Background Ruminal microbiota in early life plays critical roles in the life-time health and productivity of ruminant animals.However,understanding of the relationship between gut microbiota and ruminant phenotypes is very limited.Here,the relationship between the rectum microbiota,their primary metabolites,and growth rate of a total of 76 young dairy goats(6-month-old)were analyzed,and then 10 goats with the highest or lowest growth rates respectively were further compared for the differences in the rectum microbiota,metabolites,and animal's immune parameters,to investigate the potential mechanisms by which the rectum microbiota contributes to the health and growth rate.Results The analysis of Spearman correlation and microbial co-occurrence network indicated that some keystone rectum microbiota,including unclassified Prevotellaceae,Faecalibacterium and Succinivibrio,were the key modulators to shape the rectum microbiota and closely correlated with the rectum SCFA production and serum IgG,which con-tribute to the health and growth rate of young goats.In addition,random forest machine learning analysis suggested that six bacterial taxa in feces could be used as potential biomarkers for differentiating high or low growth rate goats,with 98.3％accuracy of prediction.Moreover,the rectum microbiota played more important roles in gut fermentation in early life(6-month-old)than in adulthood stage(19-month-old)of goats.Conclusion We concluded that the rectum microbiota was associated with the health and growth rate of young goats,and can be a focus on the design of the early-life gut microbial intervention.