Improving sire reproductive performance in artificial insemination (AI) programs and maximizing the use of sires with
valuable genomes are high on the list of priorities for livestock breeders in the United States and worldwide. While fixed-time AI and
accurate estrous detection have already ameliorated the reproductive management of cows and sows, substantial gains remain to be
made in the selection and utilization of male animals for field AI. In addition to better, more objective evaluation of breeding soundness
and semen quality, numbers of spermatozoa per AI dose could be reduced and numbers of AI doses per collection could be increased
without sacrificing conception rates if the fittest spermatozoa can be purified from raw semen and protected from adverse effects of
dying and decaying spermatozoa present in both the fresh and the extended semen. The present article reviews recent progress in
methodology for semen purification, including nanopurification and semen/extender supplementation with antioxidants.