From clinic to lab: Sperm parameters for equine in vitro embryo production

Equine in vitro embryo production (IVP) offers a valuable opportunity to enhance the efficient utilization of genetically and economically valuable horses. In cases of subfertility, sudden death, emergency euthanasia, or limited sperm availability, IVP becomes the only viable option to produce offspring. Due to steadily improving success rates, IVP has become one of the most sought-after assisted reproductive techniques. The rising global demand has created a clear need for veterinarians and stallion owners to provide IVP-suitable sperm, where the selection of intact sperm for intracytoplasmic sperm injection (ICSI) or conventional in vitro fertilization (IVF) is critical for fertilization and optimal embryo development. Achieving this demand requires careful consideration of animal selection, sperm processing, and sperm selection techniques, linking the day-to-day clinical practice with laboratory requirements. In this review, we summarize research on stallion and sperm parameters relevant to IVP, aiming to provide practical guidance for improving in vitro reproductive outcomes.