Effects Of Guiqi Yimu Compound Preparation On Rumen Bacteria And Fermentation Function Of Postpartum Dairy Cattle

Negative energy balance（NEB）in postpartum dairy cows is thought as one of the main factors that cause postpartum ketosis,mastitis,retained placenta,inflammatory bowel disease,and endometritis.Numerous studies have confirmed that the changes of postpartum dairy cow rumen microflora are closely related to negative energy balance.Guiqi Yimu compound preparation has the effect of tonifying qi and activating blood,and has a good effect on the syndrome of postpartum qi deficiency and blood stagnation.Preliminary research by the project team showed that the formula can have certain health care effects on postpartum dairy cows.It is speculated that it may be related to its regulation of rumen fermentation function,but it needs to be further verified.Therefore,16S rRNA high-throughput sequencing and GC-MS/MS targeted metabolomics technology were applied in this experiment to elucidate the effect of the formula on postpartum dairy cow rumen microflora and its main metabolite short-chain fatty acids.The results are as follows:1.The results of 16S rRNA high-throughput sequencing showed that the dominant flora at the phylum level of the two groups of dairy cows were Firmicutes and Bacteroidota;the dominant flora at the genus level were Prevotella,Christensenellaceae and Ruminococcus_NK4A214_group.Compared with the control group,bacterial abundances of Proteobacteria,Escherichia-Shigella and Bacteroides the test group were significantly increased（P<0.01）,the abundance of Lactobacillus and Subdoligranulum was significantly increased（P<0.05）,the abundance of Actinobacteriota,Prevotella₇ and Lachnospira were significantly decreased（P<0.05）in dairy cows administrating Guiqi Yimu compound preparation seven days.2.The results of GC-MS/MS targeted metabolomics technology showed that the concentrations of propionic acid and isobutyric acid were notably increased（P<0.05）,and those of acetic acid,butyric acid,valeric acid and isobutyric acid were prone to increase（P>0.05）,while the content of caproic acid were prone to decrease（P>0.05）in dairy cows administrating Guiqi Yimu compound preparation seven days.3.The results of correlation analysis showed that Lactobacillus,Bacteroides,Subdoligranulum,Agathobacter,Faecalibacterium and Allobaculum were significantly positively correlated with rumen propionic acid content,while Streptococcus and Serratia were significantly negatively correlated with ruminal propionic acid content.Bacteroides and Romboutsia were significantly positively correlated with rumen isobutyric acid content,while Serratia,Streptococcus and Faecalibacterium were significantly negatively correlated with rumen isobutyric acid content.Conclusion:Guiqi Yimu compound preparation could improve NEB in postpartum dairy cows via regulating the rumen bacterial flora and its fermentation function.This study revealed the health-care mechanism of Guiqi Yimu Formula on postpartum dairy cows from the perspective of rumen bacterial flora and short-chain fatty acids.