Freezing epididymal sperm from white rhinoceros (Ceratotherium simum) treated with different cryodiluents

Testes were collected from 2 hunted rhinoceros bulls in Tswalu Desert Reserve in the Kalahari. One was breeding, the other non-breeding. Testes were collected 1 hour after death, transported on ice, and processing began 3 hours thereafter. Sperm were frozen in 0.25 ml straws at 150 million sperm/ml. Straws were cooled to 4 degress and equilibrated for 6 hours. Sperm treatments were evaluated for progressive motility at pre-freeze and at post-thaw. There was a marked difference in motility between breeding and non-breeding male rhinos. There was a noticeable difference between epipidymides of the breeding male, with one epipidymis being half the size of the other, which contained no sperm. No detectable difference in sperm morphology between the 2 bulls. The results suggest that Triladyl +5% FCS would be suitable for freezing the sperm of a white rhino breeding male.