Association between weaning stress and rumen microbiota in goat kids: evidence from granger causality and randomized controlled trial validation

Objective: Although there is some evidence linking weaning stress to altered gut flora and stunted development, the exact nature of this relationship is still up for debate. Methods: In this study, we employed Granger causality inference to compare the dynamic changes in gastrointestinal microbiota between stressed and non-stressed goat kids, and we validated our findings through a randomized controlled trial involving rumen microbiota transplantation. Results: Our findings indicated that the alpha diversity and microbial maturity of the rumen microbiota in stressed kids were significantly lower than those in non-stressed kids during the weaning period (p<0.05). Furthermore, the rumen microbiota at pre-weaning could accurately predict the body weight changes during weaning stress period (R² = 0.99, root-mean-square error of prediction = 0.19). We found that the majority of high-abundance rumen bacteria (89.22%) were retained by the cultured rumen microbiota, and that transplanting this microbiota successfully changed the rumen microbiota (analysis of similarity of microbiota, p<0.05), improved growth performance (p<0.05) during weaning, and enhanced microbial maturity (p<0.05), but had no effect on the gut microbiota (p>0.05). Additionally, transplantation of the cultured rumen microbiota reduced intestinal permeability and inflammation while increasing antioxidant levels in weaned kids (p<0.05). Conclusion: These findings provide evidence for the association between rumen microbiota and weaning stress, demonstrating that manipulating rumen microbiota is an effective strategy for alleviating weaning stress in goat kids.