Abstract:
Semen cryopreservation and artificial insemination (AI) are potentially valuable methods for supporting
the breeding management of endangered species like the Asian elephant. Cryopreservation of Asian elephant
semen has however proven problematic with respect to maintenance of both adequate semen
quality and fertility post-thaw. In this study, nine ejaculates from three adult bulls were used to compare
the influence of extender (TEST versus INRA96 ) and penetrating cryoprotectants (3% glycerol, 5% glycerol
and 4% methylformamide) on post-thaw semen quality. We demonstrate that not only the freezing
process, but also the quality of the semen before freezing, significantly influences the freezability of Asian
elephant semen. Pre-freeze motility, viability, semen volume, semen pH, sperm concentration and the
incidence of sperm mid-piece and tail abnormalities all significantly (p < 0.05) affected post-thaw semen
quality. While extender and cryoprotectant did not significantly affect any of the above semen quality
parameters post-thaw, the skim-milk based extender (INRA96 ) preserved DNA integrity better
(p < 0.05) than the egg yolk extender (TEST). Considerable between-ejaculate variation in all post-thaw
semen quality parameters was also noted. It is concluded that strict criteria for semen quality is essential
for the selection of Asian elephant bull ejaculates suitable for cryopreservation; stricter initial selection
should improve the mean post-thaw quality.
