Sperm collection in rhinoceros via urethral catheterization

Assisted reproductive technologies are playing an ever-increasing role in the management of ex situ rhinoceros populations. Traditionally, sperm collection in rhinos is conducted via electroejaculation (EEJ) or gamete rescue. Sperm collection via urethral catheterization (UC) is gaining popularity in wildlife reproductive sciences as it requires less specialized equipment, is faster, and less stimulatory than EEJ. This study investigated the use of UC to collect sperm from Southern white (Ceratotherium simum simum; n = 3) and Eastern black (Diceros bicornis michaeli; n = 6) rhinoceros as an alternative or complementary to collection via EEJ. UC samples (n = 14) exhibited high sperm concentration (1.6 ± 0.49 ×10⁹ sperm/mL) and low volume (0.98 ± 0.26 mL). Samples obtained via EEJ (n = 11) were of moderate sperm concentration (0.14 ± 0.05 ×10⁹ sperm/mL) and high volume (30.6 ± 7.2 mL). UC samples were processed for cryopreservation in OptiXcell extender. Motility of UC sperm decreased post-thaw (56 ± 2.4%) over pre-freeze (77.1 ± 3.2%; P < 0.05), with longevity data consistent to prior results published for sperm collected via EEJ. These results suggest sperm quality and cryo-survival are not impacted by the collection method. Since EEJ was conducted after UC, sperm parameters could not be compared between the two methods. Results indicate that UC is a viable alternative to EEJ for sperm collection in rhinoceros.