Collected ruminal fluids were used to extract DNA by E.Z.N.A. Soil DNA kit (Omega Bio-tek, US), and the concentrations and pureness of DNA were examined in YBS-380 and NanoDrop2000. 1% agarose gel electrophoresis to detect DNA integrity, after that, fragment DNA and selected DNA fragments about 400 bp. Constructed pair-end DNA library using NEXTFLEX Rapid DNA-Seq (Bioo Scientific, US). After bridge PCR amplification, metagenomic sequencing was conducted by Illumina NovaSeq/Hiseq Xten (Illumina, US).