Sperm rescue in wild African elephants

This study investigated ways of improving the usefulness of ,1700mL of poor-quality frozen semen collected from wild African elephant (Loxodonta africana) bulls. Ten semen samples from six bulls, frozen with 5% glycerol in Berliner cryomedium, with or without prior removal of the seminal plasma by centrifugation, were tested. All samples were subjected to the following density-gradient centrifugation treatments: no centrifugation (control), sham centrifugation, Percoll, OptiPrep, Isolate and PureSperm. Sample evaluation included motility, concentration, viability, acrosomeintegrityandnormalmorphologyafterthawingandaftergradientcentrifugation.Motilitywasalsoevaluated3h after thawing. While all treatments were similar to the Control in acrosome integrity and normal morphology, significant differenceswerenotedinconcentration,viabilityandmotility.SamplestreatedbyPercollshowedthebestmotility,which was maintained unchanged over 3h of incubation (378C). Correlations between manual and automated evaluations of concentration were high (cytometer; rho ¼0.92), but were lower for viability (cytometer; rho ¼0.57) and motility (computer-aided sperm analysis; rho ¼0.66). By performing density centrifugation, the quality of these sperm samples maybeimprovedtoalevelsuitable forartificial inseminationinelephants.Althoughasizeable proportionofcellsarelost in the process, combining samples may still allow for multiple inseminations. Additional keywords: conservation, cryopreservation, directional freezing, endangered, spermatozoa.