Visual motility assessment is highly subjective and should therefore be replaced by automated system
That is the conclusion of a comparative study on boar semen quality assessment. Two independent person reviewed pig semen samples three consecutive days for concentration and motility parameters. Same samples were assessed by desktop CASA systems too. They found limited agreement between subjective and CASA method. Same bias has been detected between reviewers. If you are serious about sperm quality control, you should find objective automated systems to do the job.