Animal protein-free OptiXcell and shortened equilibration periods can replace egg yolk-based extender and slow cooling for rhinoceros semen cryopreservation

摘要

OptiXcell (OP) was tested as an animal protein-free alternative to an egg yolk-based extender for rhinoceros semen cryopreservation and shorter chilling/equilibration periods were evaluated. Semen was collected from three rhinoceros species: black (Diceros bicornis; n = 2), white (Ceratotherium simum; n = 2), and greater one horned (GOH; Rhinoceros unicornis; n = 3). Controls were diluted with equine extender (EQ) or OP and equilibrated for 1 h. Treatments were diluted with extender and cooled for 15 min (fast: FEQ; FOP) or not cooled (immediate: IEQ; IOP), prior to cryopreservation. Motility decreased post-thaw (EQ: 50.7 +/- 5.2%; OP: 52.9 +/- 3.4%) from fresh (82.9 +/- 2.9%), was higher in OP than IOP (38.6 +/- 4.9%; P 0.05). Morphology did not differ between fresh (75.0 +/- 4.9% normal) and any treatment group (70.0-77.8%) or over time (P > 0.05). OptiXcell is comparable to egg yolk-based EQ when used for rhinoceros semen cryopreservation. Furthermore, chilling/equilibration can be reduced with little impact on sperm characteristics.