| Studies in models and monogastric animals indicate that there may be "core microbial flora" in the animal's digestive tract that is mainly affected by the physiological state of the host and "non-core microbial flora" that are mainly affected by environmental factors."Core microbial flora" has a more direct impact on host immune,endocrine,metabolic and other physiological processes.After the changed diet and other environmental conditions are restored,it guides the recovery of "non-core microbial flora".At present,the definition of ruminant core microorganisms is mainly based on statistics of all individuals' common microorganisms,and the difference between core microorganisms and non-core microorganisms is ignored in the way of interaction with the host.Therefore,on the basis of this method,the microbial flora was regulated by the environmental changes in the digestive tract caused by the change of the daily feed concentrate-to-crude ratio and the immune stress state of the host caused by lipopolysaccharide injection,so as to define the core microorganisms more accurately.In the first part of the test,the shared microbes of dairy goats were defined.In this test,shared microbial statistics were collected from the rumen fluid of 12 Laoshan dairy goats treated with the same diet,and 57 shared genus including Prevotella and Bacteroides were obtained,with the above microorganisms as the key research,in order to obtain the core microbial flora affected by the host's physiological status.In the second part of the test,the effects of different precision-roughness ratios on the microbes of dairy goats were studied.Six dry goats from the same period were randomly divided into 2 Group,3 goats of each group,were fed with high concentrate(TA group,diet to coarse ratio 5: 5)and low concentrate(CA group,diet to coarse ratio 2: 8)diet.After 2 weeks,blood samples were collected,serum indicators were measured,and rumen fluid samples were collected for volatile fatty acid detection,16 S rDNA sequencing,and LC-MS metabolome detection.Compared with the control group,The rumen pH was significantly reduced(P<0.05),the rumen acetic acid concentration was significantly reduced(P <0.05),and the propionic acid concentration was significantly increased(P <0.05).The rumen ethylene-propylene ratio was significantly reduced(P <0.01).For metabolites,the content of1,5-diaminopentane,cadaverine,and folinic acid in the TA group was significantly increased(P <0.05),L-ascorbate,methylmalonic acid,menaquinone,arachidic acid,and lignoceric acid,erucic acid,nervonic acid,stearic acid,and aldosterone were significantly reduced(P <0.05).The main metabolic pathways affected were glutathione metabolism,unsaturated fatty acid biosynthesis,etc.,which indicated that affect host rumen environment to affect rumen microorganisms.Comparing the two groups of microorganisms,the relative abundance of Selenomonas and Schwartzia in the TA group was significantly increased(P <0.05);The relative abundances of Bacteroidetes_unclassified,Prevotellaceae_unclassified,Clostridiales_unclassified,Bacteria_unclassified,Planctomycetaceae_unclassified,Verrucomicrobia_unclassified Christensenella and Spirochaeta in the TA group were significantly decreased(P <0.05).In the third part of the test,the effect of jugular vein infusion of lipopolysaccharide(LPS)on the microbes of dairy goats was studied.After prefeeding the above 6 dairy goats under the same diet for two weeks,they were randomly divided into 2 Group,3 goats of each group,Jugular vein perfusion LPS treatment(TF group)and jugular vein perfusion saline treatment(CF group),LPS(Escherichia coli O111: B4)perfusion dose was 0.03 ? g / kg.After 24 hours,blood samples were collected,serum indicators were measured,and rumen fluid samples were collected for volatile fatty acid detection,16 S rDNA sequencing,and LC-MS metabolome detection.Compared with the control group,the serum and high-density lipoprotein(HDL)concentrations in the serum of dairy goats in the TF group were significantly reduced(P <0.05),and the rumen pH was significantly reduced(P <0.05).At the same time,the total volatile fatty acids in the rumen The concentrations of acetic acid,propionic acid and butyric acid increased significantly(P <0.05),and the feed intake of dairy goats decreased significantly(P <0.05).For metabolites,methionine,L-valine,L-threonine,L-phenylalanine,tyrosine,5-aminovaleric acid,L-tyrosine,glycine,L-serine,Isobutyric acid,D-methionine and so on were significantly increased(P <0.05),kynurenc acid,anthranilic acid,xanthine acid,N-methyltryptamine,N-acetyl-D-phenylalanine,17 ?-hydroxyprogesterone,progesterone,corticosterone,3-succinylpyridine and so on were significantly reduced(P <0.05),the main metabolic pathways affected are mineral metabolism,tryptophan metabolism,aminoacyl-tRNA biology Synthesis,phenylalanine,tyrosine and tryptophan biosynthesis,protein digestion and absorption,ubiquinone and other terpenoid quinone biosynthesis,thiamine metabolism and so on,suggest that different jugular vein perfusion LPS affects the host immune response Stress,energy metabolism,and rumen environment have an effect on rumen microorganisms.Comparing the two groups of microorganisms,the relative abundance of the Lachnospiraceae_unclassified,Firmicutes_unclassified,Rikenella,Subdivision5_genera_incertae_sedis and Spirochaetes_unclassified in the TF group was significant increased(P <0.05);the relative abundances of Bacteroidetes_unclassified,Paraprevotella,Deltaproteobacteria_unclassified,and Centipeda were significantly decreased(P <0.05).For the rumen microorganisms of dairy goats under the two perfusion treatments,9 different bacterial genera were obtained,including7 shared bacterial genera and 2 non-shared bacterial genera.The results showed that the effect mechanism of changing dietary concentrate-to-crude ratio and jugular venous infusion of LPS on the host was different,and the altered microorganisms were also different,but both could act on rumen shared and non-shared microorganisms.Six genus including Lachnospiraceae_unclassified,Firmicutes_unclassified,Rikenella,Subdivision5_genera_incertae_sedis,Paraprevotella,Deltaproteobacteria_unclassified were observed were only affected by jugular venous perfusion LPS,which may be the core microorganisms with more direct impact on the host. |
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