169 QUALITATIVE ASSESSMENT OF ENDANGERED ARABIAN TAHR/IBEX (HEMITRAGUS JAYAKARI) SEMEN USING BIOXCELL^® AND TRILADYL^® EXTENDERS

Abstract

The Arabian tahr/ibex is a small species of goat-antelope-like animal, indigenous to the United Arab Emirates and with a larger population in Oman. Although the animal was discovered in 1894, its numbers continue to decline, and the animal has been classified on the IUCN red list as an endangered species. Little is known about the male reproduction, specifically, extending and cryopreserving semen. This provides a crucial tool for the ex situ conservation of this endangered species. The objective of this study was to evaluate sperm characteristics of the Arabian ibex after dilution in 2 commercial extenders, namely Bioxcell^® and Triladyl^® based on multiple qualitative parameters. Semen was collected using an electroejaculator from males (n = 4, ~4 years old) during the reproductive season (February–April). Ejaculates were divided into 2 aliquots and extended 1 : 2 in Bioxcell^® or Trilidayl^® at 37°C. Diluted semen was evaluated for motility with computer-assisted semen analysis (Sperm Vision^®, Minitube, Verona, WI, USA). Morphologically, samples were examined with eosin and nigrosin stain under light microscopy, in addition to structural or ultrastructural evaluation with the use of scanning (SEM) or transmission (TEM) electron microscopy. Viability tests were carried out with a LIVE/DEAD^® sperm viability kit (Invitrogen, Carlsbad, CA, USA); samples were examined using a fluorescent microscope (Olympus BX51) or with a flow cytometer (FACSAria^TM III, FACSDiva software, BD) with an average flow of 20 000 sperm/event. Sperm samples were liquefied (37°C/5 min), washed with 0.9% NaCl, centrifuged (2000 rpm for 3 min), and filtered using 40-µm nylon mesh (BD, USA) before FACS analysis. Our data showed that semen diluted with Triladyl^® had higher motility compared with samples extended with Bioxcell^® (60 v. 41%). While eosin and nigrosin staining showed very low morphological abnormalities with both extenders (less than 2%), SEM and TEM assessment demonstrated slightly high incidents of cracked tails, ruptured membrane, and broken midpeace with samples diluted with Bioxcell^®. Viability test showed that samples extended with Triladyl^® had higher percentages of live sperm (33%) compared with Bioxcell^® (21%). Similar viability numbers were obtained with FACSAria^TM III. These results indicate that diluting Arabian ibex semen with Triladyl^® would provide improved motility, morphology, and viability compared with Bioxcell^®. These findings would be extremely useful for an ex situ conservation program of the Arabian tahr/ibex.