[1] CONRAD R.The global methane cycle:recent advances in understanding the microbial processes involved[J].Environmental Microbiology Reports,2009,1(5):285-292.

[2] LENHART K,BUNGE M,RATERING S,et al.Evidence for methane production by saprotrophic fungi[J].Nature Communications,2012,3:1046.
[3] LIU J G,CHEN H,ZHU Q A,et al.A novel pathway of direct methane production and emission by eukaryotes including plants,animals and fungi:an overview[J].Atmospheric Environment,2015,115:26-35.
[4] BI?I? M,KLINTZSCH T,IONESCU D,et al.Cyanobacteria,the most ancient and abundant photoautotrophs on earth produce the greenhouse gas methane during photosynthesis[J].BioRxiv,2019:398958.
[5] LIU Y C,WHITMAN W B.Metabolic,phylogenetic,and ecological diversity of the methanogenic archaea[J].Annals of the New York Academy of Sciences,,2008,1125(1):171-189.

[6] LYU Z,SHAO N N,AKINYEMI T,et al.Methanogenesis[J].Current Biology,2018,28(13):R727-R732.
[7] THAUER R K,KASTER A K,SEEDORF H,et al.
Methanogenic archaea:ecologically relevant differences in energy conservation[J].Nature Reviews Microbiology,2008,6(8):579-591.

[8] SÖLLINGER A,URICH T.Methylotrophic methanogens everywhere-physiology and ecology of novel players in global methane cycling[J].Biochemical Society Transaction,2019,47(6):1895-1907.

[9] JOHNSON K A,JOHNSON D E.Methane emissions from cattle[J].Journal of Animal Science,1995,73(8):2483-2492.

[10] MCALLISTER T A,NEWBOLD C J.Redirecting rumen fermentation to reduce methanogenesis[J].Australian Journal of Experimental Agriculture,2008,48(2):7-13.

[11] DENMAN S E,FERNANDEZ G M,SHINKAI T,et al.Metagenomic analysis of the rumen microbial community following inhibition of methane formation by a halogenated methane analog[J].Frontiers in Microbiology,2015,6:1087.
[12] WANG K,NAN X M,CHU K K,et al.Shifts of hydrogen metabolism from methanogenesis to propionate production in response to replacement of forage fiber with non-forage fiber sources in diets
in vitro[J].Frontiers in Microbiology,2018,9:2764.
[13] LAN W,YANG C L.Ruminal methane production:associated microorganisms and the potential of applying hydrogen-utilizing bacteria for mitigation[J].Science of the Total Environment,2019,654:1270-1283.
[14] HENDERSON G,COX F,GANESH S,et al.Rumen microbial community composition varies with diet and host,but a core microbiome is found across a wide geographical range[J].Scientific Reports,2015,5:14567.
[15] SESHADRI R,LEAHY S C,ATTWOOD G T,et al.Cultivation and sequencing of rumen microbiome members from the Hungate1000 collection[J].Nature Biotechnology,2018,36(4):359-367.

[16] KITTELMANN S,SEEDORF H,WALTERS W A,et al.Simultaneous amplicon sequencing to explore co-occurrence patterns of bacterial,archaeal and eukaryotic microorganisms in rumen microbial communities[J].PLoS One,2013,8(2):e47879.
[17] NEWBOLD C J,LÓPEZ S,NELSON N,et al.Propionate precursors and other metabolic intermediates as possible alternative electron acceptors to methanogenesis in ruminal fermentation
in vitro[J].British Journal of Nutrition,2005,94(1):27-35.

[18] VAN ZIJDERVELD S M,GERRITS W J J,APAJALAHTI J A,et al.Nitrate and sulfate:effective alternative hydrogen sinks for mitigation of ruminal methane production in sheep[J].Journal of Dairy Science,2010,93(12):5856-5866.

[19] BEAUCHEMIN K A,UNGERFELD E M,ECKARD R J,et al.Review:fifty years of research on rumen methanogenesis:lessons learned and future challenges for mitigation[J].Animal,2020,14(Suppl.1):S2-S16.
[20] PATRA A K.Prediction of enteric methane emission from buffaloes using statistical models[J].Agriculture,Ecosystems & Environment,2014,195:139-148.
[21] SHI W B,MOON C D,LEAHY S C,et al.Methane yield phenotypes linked to differential gene expression in the sheep rumen microbiome[J].Genome Research,2014,24(9):1517-1525.

[22] BELANCHE A,DE LA FUENTE G,NEWBOLD C J.Study of methanogen communities associated with different rumen protozoal populations[J].FEMS Microbiology Ecology,2014,90(3):663-677.

[23] JANSSEN P H,KIRS M.Structure of the archaeal community of the rumen[J].Applied and Environmental Microbiology,2008,74(12):3619-3625.

[24] PATRA A,PARK T,KIM M,et al.Rumen methanogens and mitigation of methane emission by anti-methanogenic compounds and substances[J].Journal of Animal Science and Biotechnology,2017,8:13.
[25] HOOK S E,WRIGHT A D G,MCBRIDE B W.Methanogens:methane producers of the rumen and mitigation strategies[J].Archaea,2010,2010:945785.
[26] MORGAVI D P,FORANO E,MARTIN C,et al.Microbial ecosystem and methanogenesis in ruminants[J].Animal,2010,4(7):1024-1036.

[27] HEGARTY R S,BIRD S H,VANSELOW B A,et al.Effects of the absence of protozoa from birth or from weaning on the growth and methane production of lambs[J].British Journal of Nutrition,2008,100(6):1220-1227.

[28] BIRD S H,HEGARTY R S,WOODGATE R.Persistence of defaunation effects on digestion and methane production in ewes[J].Australian Journal of Experimental Agriculture,2008,48(2):152-155.

[29] NEWBOLD C J,DE LA FUENTE G,BELANCHE A,et al.The role of ciliate protozoa in the rumen[J].Frontiers in Microbiology,2015,6:1313.
[30] GRUNINGER R J,PUNIYA A K,CALLAGHAN T M,et al.Anaerobic fungi (phylum
Neocallimastigomycota):advances in understanding their taxonomy,life cycle,ecology,role and biotechnological potential[J].FEMS Microbiology Ecology,2014,90(1):1-17.

[31] ISHAQ S L,KIM C J,REIS D,et al.Fibrolytic bacteria isolated from the rumen of north american moose (
Alces alces) and their use as a probiotic in neonatal lambs[J].PLoS One,2015,10(12):e0144804.
[32] WEI Y Q,LONG R J,YANG H,et al.Fiber degradation potential of natural co-cultures of
Neocallimastix frontalis and
Methanobrevibacter ruminantium isolated from yaks (
Bos grunniens) grazing on the Qinghai Tibetan Plateau[J].Anaerobe,2016,39:158-164.
[33] KITTELMANN S,PINARES-PATINO C S,SEEDORF H,et al.Two different bacterial community types are linked with the low-methane emission trait in sheep[J].PLoS One,2014,9(7):e103171.
[34] TAPIO I,SNELLING T J,STROZZI F,et al.The ruminal microbiome associated with methane emissions from ruminant livestock[J].Journal of Animal Science and Biotechnology,2017,8:7.
[35] DANIELSSON R,DICKSVED J,SUN L,et al.Methane production in dairy cows correlates with rumen methanogenic and bacterial community structure[J].Frontiers in Microbiology,2017,8:226.
[36] WALLACE R J,ROOKE J A,MCKAIN N,et al.The rumen microbial metagenome associated with high methane production in cattle[J].BMC Genomics,2015,16:839.
[37] POPE P B,SMITH W,DENMAN S E,et al.Isolation of Succinivibrionaceae implicated in low methane emissions from tammar wallabies[J].Science,2011,333(6042):646-648.

[38] GRAINGER C,CLARKE T,MCGINN S M,et al.Methane emissions from dairy cows measured using the sulfur hexafluoride (SF
6) tracer and chamber techniques[J].Journal of Dairy Science,2007,90(6):2755-2766.

[39] WILLIAMS S R O,MOATE P J,HANNAH M C,et al.Background matters with the SF
6 tracer method for estimating enteric methane emissions from dairy cows:a critical evaluation of the SF
6 procedure[J].Animal Feed Science and Technology,2011,170(3/4):265-276.
[40] PATRA A K.Recent Advances in measurement and dietary mitigation of enteric methane emissions in ruminants[J].Frontiers in Veterinary Science,2016,3:39.
[41] RYMER C,HUNTINGTON J A,WILLIAMS B A,et al.
In vitro cumulative gas production techniques:history,methodological considerations and challenges[J].Animal Feed Science and Technology,2005,123-124:9-30.
[42] NEGUSSIE E,DE HAAS Y,DEHARENG F,et al.Invited review:large-scale indirect measurements for enteric methane emissions in dairy cattle:a review of proxies and their potential for use in management and breeding decisions[J].Journal of Dairy Science,2017,100(4):2433-2453.

[43] PATRA A K,LALHRIATPUⅡ M,DEBNATH B C.Predicting enteric methane emission in sheep using linear and non-linear statistical models from dietary variables[J].Animal Production Science,2016,56(2/3):574-584.
[44] PATRA A K,LALHRIATPUⅡ M.Development of statistical models for prediction of enteric methane emission from goats using nutrient composition and intake variables[J].Agriculture Ecosystems & Environment,2016,215:89-99.
[45] MORAES L E,STRATHE A B,FADEL J G,et al.Prediction of enteric methane emissions from cattle[J].Global Change Biology,2014,20(7):2140-2148.

[46] PATRA A K.Prediction of enteric methane emission from cattle using linear and non-linear statistical models in tropical production systems[J].Mitigation and Adaptation Strategies for Global Change,2016:1-22.
[47] KUMAR S,DAGAR S S,PUNIYA A K,et al.Changes in methane emission,rumen fermentation in response to diet and microbial interactions[J].Research in Veterinary Science,2013,94(2):263-268.

[48] MEALE S J,CHAVES A V,BAAH J,et al.Methane production of different forages in
in vitro ruminal fermentation[J].Asian-Australasian Journal of Animal Sciences,2011,25(1):86-91.

[49] MACHADO L,MAGNUSSON M,PAUL N A,et al.Effects of marine and freshwater macroalgae on
in vitro total gas and methane production[J].PLoS One,2014,9(1):e85289.
[50] PATRA A K,SAXENA J.A new perspective on the use of plant secondary metabolites to inhibit methanogenesis in the rumen[J].Phytochemistry,2010,71(11/12):1198-1222.
[51] WILLIAMS S R O,MOATE P J,DEIGHTON M H,et al.Methane emissions of dairy cows cannot be predicted by the concentrations of C8:0 and total C18 fatty acids in milk[J].Animal Production Science,2014,54(10):1757-1761.

[52] CHEN M,WOLIN M J.Effect of monensin and lasalocid-sodium on the growth of methanogenic and rumen saccharolytic bacteria[J].Applied and Environmental Microbiology,1979,38(1):72-77.

[53] MARTINEZ-FERNANDEZ G,DENMAN S E,YANG C L,et al.Methane inhibition alters the microbial community,hydrogen flow,and fermentation response in the rumen of cattle[J].Frontiers in Microbiology,2016,7:1122.
[54] HRISTOV A N,OH J,GIALLONGO F,et al.An inhibitor persistently decreased enteric methane emission from dairy cows with no negative effect on milk production[J].Proceedings of the National Academy of Sciences of the United States of America,2015,112(34):10663-10668.

[55] WRIGHT A D G,KENNEDY P,O'NEILL C J,et al.Reducing methane emissions in sheep by immunization against rumen methanogens[J].Vaccine,2004,22(29/30):3976-3985.
[56] LEE C,ARAUJO R C,KOENIG K M,et al.Effects of encapsulated nitrate on growth performance,nitrate toxicity,and enteric methane emissions in beef steers:backgrounding phase[J].Journal of Animal Science,2017,95(8):3700-3711.
[57] Van ZIJDERVELD S M,GERRITS W J J,DIJKSTRA J,et al.Persistency of methane mitigation by dietary nitrate supplementation in dairy cows[J].Journal of Dairy Science,2011,94(8):4028-4038.

[58] GUYADER J,DOREAU M,MORGAVI D P,et al.Long-term effect of linseed plus nitrate fed to dairy cows on enteric methane emission and nitrate and nitrite residuals in milk[J].Animal,2016,10(7):1173-1181.

[59] DOREAU M,ARBRE M,POPOVA M,et al.Linseed plus nitrate in the diet for fattening bulls:effects on methane emission,animal health and residues in offal[J].Animal,2017,12(3):501-507.
[60] LI X Z,LONG R J,YAN C G,et al.Rumen microbial responses in fermentation characteristics and production of CLA and methane to linoleic acid in associated with malate or fumarate[J].Animal Feed Science and Technology,2010,155(2/3/4):132-139.