A donkey is not a horse with long ears. There are important reproductive differences between both species. Jackasses have, on average, a larger penis and testicles than horses. The accessory sex glands are also larger in the donkey except for the vesicular glands. Jackasses are territorial. When confronted with a jenny in estrous they display a long precopular phase, with an intense interaction, and a short copular phase. In general, jackasses ejaculate a good quality semen, with high sperm concentration and reduced sperm abnormalities. Donkey spermatozoa move fast, having an active metabolism and producing important amounts of lactic acid and ROS. Seminal plasma (SP) is a complex fluid produced by sexual accessory glands. More than 2000 proteins are identified in donkey SP, and only a fraction are known. Some of them are antioxidant enzymes or some are involved in the jenny post-insemination endometrial reaction. Jackass SP has a lot of metabolites different than stallions with important sperm metabolism differences. However, SP has a deleterious effect on donkey sperm preservation and must be eliminated in the cryopreservation process. Post-thaw donkey sperm survival results are good (40–60%) and are similar or better than obtained results for stallion frozen/thawed semen. However, low conception rates are obtained when jennies are inseminated. Further studies are needed, taking into account recent scientific updates, in order to improve fertility results in donkeys by artificial insemination.