南アフリカのキリンの精巣上体精子保存技術の最適化

Giraffe populations have declined by 30-40% over the past three generations, resulting in local extinctions in many habitats. In contrast, the South African subspecies is stable and subject to culling in some reserves, creating opportunities for post-mortem gamete recovery to support conservation. This study evaluated the preservation potential of epididymal sperm collected from South African giraffe bulls. Paired testes from 12 bulls were collected post-mortem and placed at 5°C mobile fridge from the Sandveld Nature Reserve. Sperm was retrieved from the cauda epididymides by slicing immediately (n = 4), four hours (n = 4), six hours (n = 2), and eight hours post-mortem (n = 2). Samples were extended in tris-egg yolk (TEY) or Ark Biotechnology's proprietary flush buffer for liquid preservation at 4°C and cryopreservation. Sperm quality was assessed microscopically, and motility parameters were analyzed using two-way ANOVA. Sperm quality was maintained up to six hours post-mortem, with total motility exceeding 75%. A sharp decline occurred at eight hours (<20%). After 72 h at 4°C, Ark buffer preserved higher motility (62 ± 3.43%) than TEY (44 ± 3.21%). In contrast, TEY produced superior cryopreservation outcomes, with post-thaw motility of 70% immediately and 65 ± 2.55% after two hours, compared to Ark biotech buffer (25% and 0%, respectively). Epididymal sperm from giraffes can be effectively recovered up to six hours post-mortem without loss of quality. Ark Biotechnology's flush buffer is advantageous for short-term liquid preservation, while TEY is better suited for cryopreservation.