SEMEN CHARACTERISTICS, SPERM FREEZING, AND ENDOCRINE PROFILES IN FREE-LIVING WILDEBEEST (CONNOCHAETES-TAURINUS) AND GREATER KUDU (TRAGELAPHUS-STREPSICEROS)

Semen and endocrine characteristics were analyzed in free-living white-bearded wildebeests (Connochaetes taurinus) and greater kudu (Tragelaphus strepsiceros). Adult bulls of both species were anesthetized for standardized electroejaculation and serial blood sampling. After assessment, each ejaculate was diluted under field conditions with seven cryoprotective diluents, cooled, pellet-frozen on dry ice, stored in liquid nitrogen, and later evaluated. Mean ejaculatory volume (11.7 vs. 4.4 ml), percent sperm motility (91.0 vs. 59.0), sperm concentration/ml (850 x 10(6) vs. 380 x 10(6)), and number of motile sperm/ejaculate (6,750 x 10(6) vs. 1,090 x 10(6)) were greater (P < 0.01) in wildebeests than in kudu, respectively. Wildebeests produced fewer (P < 0.01) pleiomorphic sperm (20%) and more (P < 0.05) sperm with normal acrosomes (95.9%) than kudu (42.7 and 87.8%, respectively). Based on postthaw percent sperm motility, the diluents ranked high to low were TRIL > BF5F > TRIS > EQ > PDV > TEST > HEPT for wildebeests and EQ > BF5F > TEST > PDV > HEPT > TRIL > TRIS for kudu. For acrosomal integrity, the diluents ranked BF5F > PDV > EQ > TEST > TRIL > HEPT > TRIS for wildebeests and BF5F > EQ > PDV > TEST > TRIL > HEPT > TRIS for kudu. Mean (+/- SEM) and temporal serum luteinizing hormone concentrations did not differ (P > 0.05) between species; however, testosterone levels were sixfold greater (P < 0.01) in wildebeests than in kudu. Electroejaculation elicited a significant cortisol response in wildebeests but not in kudu. Mean circulating cortisol concentrations in electroejaculated and ACTH-treated wildebeests were similar (P > 0.05) but were half the maximal adrenal response measured in ACTH-treated kudu. Following ACTH treatment of wildebeests, mean testosterone level increased markedly (as much as 6.5 ng/ml in individual bulls). This study demonstrates striking variations in seminal/endocrine characteristics between two similar-sized bovids coexisting in the same native habitat. The results illustrate that postthaw sperm viability is highly dependent on species and cryoprotective diluent, an important consideration in formulating sperm banking strategies for wildlife species.