16S V3V4 amplicon  of bovine metagenome: feces
DNA extraction from the fecal samples was  performed with the QIAamp Fast DNA Stool Minikit extraction kit (Qiagen,  Hilden, Germany), following the manufacturer's protocol. The quality of the  DNA samples from the microorganism community was assessed by electrophoresis  on 0.8% agarose gel and concentrations were quantified in a spectrophotometer  model NanoDrop ND-2000 (Thermo Fisher Scientific, Wilmington, DE, USA). The  libraries were prepared following the Illumina recommendations. The  hypervariable region V3-V4 of the 16S rRNA gene was sequenced on a Illumina  MiSeq, with v3 Reagent kit (Illumina, San Diego, CA, USA) and the readings  produced were 2x300 bp.