Primary aim of the analysis was to identify proteomic differences in the semen samples of Bos indicus that accounts for high or low ERR. This was achieved through tandem mass-tags based quantitative proteomics approach coupled to LC-MS/MS methods. An Orbitrap Fusion Tribrid mass spectrometer (Thermo Fischer Scientific, Bremen, Germany) connected to the Easy- nLC-1200 nanoflow liquid chromatography system (Thermo Scientific) was used for data acquisition.