Study On Rumen Microbial Diversity And Metabolizable Energy Of Rumen Fluid Of Different RFI Tan Sheep

The breeding of tan sheep is one of the important economic income of Ningxia,but the high cost of breeding restricts the development of tan sheep industry.The measurement of RFI can intuitively understand the feed efficiency of Tan sheep,and the rumen is a key organ affecting feed digestion and absorption.Therefore,the rumen internal environment,rumen microbes and small molecules of rumen metabolism of RFI Tan sheep of different genders were studied.Through the characterization of rumen fermentation parameters,key microorganisms and small molecules of metabolism affecting RFI were screened.As biomarkers to provide theoretical support for genetic breeding molecular selection of tan sheep with high feed efficiency.The following experiments were carried out in this study:In this study,345 6-month-old Tan sheep(163 male sheep and 182 female sheep)with similar body weight(30±5kg)were used to fix the sheep with neck clip and fed the same pellet diet without restricted exercise.The transitional period lasted for 15 days,the pre-trial period lasted for 10 days and the formal trial period lasted for 50 days.After the RFI of each sheep was calculated by multiple regression model,the sheep were classified into high-RFI group and low-RFI group respectively,and extremely Low RFI beach sheep(EH-RFI)and extremely Low RFI beach sheep(EL-RFI)were selected.Rumen fluid was collected from 7 male and female sheep with extremely Low RFI and 8 male and female sheep with extremely High RFI.Conduct follow-up tests.Experiment 1:GC-MS was used to detect VFA in rumen fluid of Tan sheep,and combined with rumen fluid pH collected before slaughter.The results showed that there was no significant difference in rumen pH between males and females with different RFI.The total fatty acid content of ewes was significantly higher than that of RAMS.The contents of butyric acid,isobutyric acid and isovaleric acid in low RFI Tan sheep in ram group were significantly higher than those in high RFI sheep(P<0.05),but there were no significant differences in RFI and fatty acid contents in female sheep group(P>0.05).The contents of propionic acid,valerate acid and caproic acid in ewes were higher than those in RAMS(P<0.05).There was no significant difference in b/C ratio among all groups(P>0.05).In general,rumen pH and RUMen VFA contents are different between male and female sheep,which may result in different fermentation modes.Low RFI flat sheep have higher contents of butyric acid,isobutyric acid and isovalerate acid,which can be used as an important biomarker of high feed efficiency.Experiment 2:The amplification of bacterial 16S rRNA gene in rumen fluid samples of Tan Sheep was sequenced by sequencing technology.The results showed that rumen microbial diversity and richness had no significant changes in male and female sheep(P>0.05),and PCoA principal coordinate analysis showed no significant separation of rumen microbial community.However,in the extremely high group,the abundance of Bacteroidetes in male sheep was significantly higher than that in female sheep,the abundance of actinomycetes in female sheep was significantly higher than that in male sheep,and the abundance of proteobacteria in male sheep was significantly higher than that in female sheep(P<0.05).In extremely high group,the abundance of Olsenella was significantly higher in female sheep than in male sheep,the abundance of Prevotella was significantly higher in male sheep than in female sheep,and the abundance of Erysipelotrichaceae_UCG-002 was significantly higher in male sheep than in female sheep(P<0.05).Selenomonas bacteria was significantly higher in male sheep than female sheep in extremely low group(P<0.05).Among the different RFI phenotypes of RAMS,Methanobrevibacter in euryarchaea in low RFI group was significantly higher than that in high RFI group,and Proteobacteria in low RFI group was significantly lower than that in high RFI group(P<0.05).In conclusion,gender is an important factor affecting rumen microbial differences,and Methanobrevibacter flora in rumen is associated with low RFI tan sheep.Experiment 3:LC-MS metabolomics sequencing technology was used to detect metabolic small molecules in rumen fluid.The metabolite data were analyzed by R program,the orthogonal partial least squares discriminant analysis and principal component analysis were used for visual analysis,and the differential metabolites were identified by T test,FC value and ROC curve.The results showed that there were four different metabolites in ewes,PA,amino-propanol,trimethylamine and 3-methyl-l-butylamine were highly expressed in low RFI sheep.There were 28 different metabolites in male sheep,pyridoamine(VB6),biotin(VB7),riboflavin(VB2)and flavin adenine dinucleotide were highly expressed in low RFI,mainly involved in vitamin digestion and absorption metabolic pathway.Malic acid was highly expressed in low RFI sheep,9,10-DIHOME,CIS-9,10-epoxy stearic acid,12,13-DIHOME,DL-2-hydroxyl stearic acid were highly expressed in low RFI sheep,Lysope 18:0,Pysope 16:Lysope(16:1(9Z)/0:0)was highly expressed in low RFI sheep.In general,gender has significant effects on rumen fluid metabolites of Tan sheep with different RFI.The types and quantities of differential metabolites in female sheep were lower than male Tan sheep with RFI.RFI is mainly affected by the following aspects:1.Energy metabolism,such as TCA cycle and fatty acid metabolism;2.Vitamin digestion and absorption,and protein turnover in the rumen.Above all,gender affects rumen microbes and metabolism.The contents of butyric acid,isobutyric acid and isovaleric acid in low RFI ram were significantly higher than those in high RFI ram.The contents of propionic acid,valerate acid and caproic acid in ewes were higher than those in RAMS.The number of firmicutes may be related to RFI.Methanobrevibacter and actinomycetes of phagoarchaea were more abundant in the rumen of sheep with low RFI.There were 28 different metabolites in rumen fluid of sheep.Mainly involved in nucleic acid metabolism,TCA cycle,vitamin metabolism and lipid metabolism.Veillon UgG-002 and Methanobacteria were closely related to fatty acids and metabolites in rumen.