Evaluation for bioavailability of rumen protected methionine and its effects on rumen microorganisms in Hulun Buir sheep by in vitro fermentation
The purpose of this study was to investigate the bioavailability of rumen-protected methionine(RPMet,coa-ted with corn starch and palm oil)in the rumen in vitro fermentation system of Hulun Buir sheep and the effects of rumen-pro-tected methionine on rumen microbial groups.The rumen fluids of four female Hulun Buir sheep with fistulas were taken for in vitro fermentation test.The degradation rate of RPMet in the fermentation system was determined at the initial stage of fermen-tation and 2 h,4 h,6 h,8 h,12 h and 24 h after fermentation.Five parallel treatments were set up at each fermentation time node,and the fermentation broth was taken at the above seven time nodes for 16S rDNA sequen-cing analysis.The results showed that the degradation rate of RPMet was less than 30.0%at 8 h after fermentation in the in vitro fermentation system,indicating that the coating effect of the product was good.The sequencing results showed that the Simpson index at 24 h after fermentation was significantly lower than that at 12 h after fermentation(P＜0.05).Principal coordinateanalysis(PCoA)couldshowthe β-diversity of spe-cies.The results of this study showed that there were significant differences in the clustering results at each time point(P＜0.05).The relative abundance of Bacteroidetes,Ruminococcus and Prevotella increased significantly within 8 h after fermen-tation,and decreased significantly after 12 h of fermentation(P＜0.05).The relative abundance of Firmicutes,Euryarchae-ota,Methanobrevibacter,Succiniclasticum and Oscillibacter decreased significantly within 12 h after fermentation,and then in-creased significantly(P＜0.05).In summary,the coating effect of the RPMet product is good.The Prevotella and Ruminococ-cus act as main genera to degrade the coating layer of corn starch during the early fermentation period,while excessive degra-dation of RPMet significantly increase the abundance of Methanobrevibacter.
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