The metagenome of cow manure
Qualified genomic DNA was firstly fragmented by sonication to a size of 350bp, and  then end-repaired, A-tailed, and adaptor ligated using NEBNext Ltra DNA Library  Prep Kit for Illumina (NEB, USA) according to the preparation protocol. DNA fragments  with length of 300-400 bp were enriched by PCR. At last, PCR products were purified  using AMPure XP system (Beckman Coulter, Brea, CA, USA) and libraries were analysed  for size distribution by 2100 Bioanalyzer (Agilent, Santa Clara, CA) and quantified using  real-time PCR. Genome sequencing was performed on the Illumina NovaSeq X Plus sequencer using the pair-end technology (PE 150)