Body and Testicular Biometry and Epididymal Sperm Characteristics in Sambar Deer (Rusa unicolor (Kerr, 1792))

Characterising body and reproductive morphometry and their association with epididymal sperm quality can contribute to the conservation of sambar deer (Rusa unicolor). Five adult males maintained in captivity at the Getúlio Vargas Zoobotanical Park (Salvador, BA, Brazil) were captured, anaesthetised, and subjected to bilateral orchiectomy as part of a population-control strategy. Body measurements included head circumference, thoracic diameter, total length, withers height, and body weight. The length, width, thickness, and weight of the testes and epididymides were measured, and the gonadosomatic index was estimated. Spermatozoa were recovered from the epididymal tail by slicing and flotation, and their morphology, membrane integrity, and kinematic parameters were assessed using a computerised computer-assisted semen analysis (CASA) system. Mean kinematic parameters were: total motility (80.61% ± 18.33%), progressive motility (54.95% ± 16.55%), average path velocity-VAP (60.58 ± 12.38 μm/s), and percentage of normal spermatozoa (77.80% ± 6.14%). Withers height showed significant positive correlations (p < 0.05) with most reproductive parameters, including testicular weight (r = 0.936), testicular volume (r = 0.936), testicular area (r = 0.878), epididymal thickness (r = 0.882), total sperm recovered (r = 0.939), progressive motility (r = 0.888), and percentage of normal spermatozoa (r = 0.968). Additionally, testicular volume, thickness, epididymal length, epididymal width, and epididymal thickness showed significant positive correlations (p < 0.05) with most of the sperm parameters studied. These findings provide important preliminary data for future investigations on the reproductive potential of this species.