Investigation of scrotal circumference, testicular dimensions and semen characteristics of the vulnerable Arabian oryx (Oryx leucoryx): an approach supports the future use of artificial insemination

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Data regarding semen collection and characteristics in Arabian oryx are not available so far. Therefore, the current study aimed to evaluate scrotal circumference, testicular dimension and semen characteristics in four age groups of this species. Eleven male Arabian oryx bulls were divided into four groups according to age: group 1: 3 years old (n = 2); group 2: 4 years old (n = 2); group 3: 5 years old (n = 2) and group 4: 10 years old (n = 3). After immobilisation, scrotal circumference, testicular dimensions, volume and weight and gonadosomatic index (GSI) were estimated for each animal. Semen was collected from each male on a weekly basis for 3 weeks. Immediately after collection, semen was evaluated for volume, pH, osmolality total motility (TM), forward progressive motilities (PM) using a phase microscope. Furthermore, TM, PM, progressive velocity (PV), curvilinear velocity (VCL) and pathway velocity (VAP) have been evaluated using computer-assisted sperm analyser (CASA). Sperm concentration was evaluated using a haemocytometer, whereas sperm morphology was detected using phase contrast microscopy and staining methods by eosin-nigrosin and Spermac stains. Sperm viability was assessed using eosin-nigrosin stain under light microscopy and Sybr14/PI stain under fluorescence microscopy. The current findings indicated a positive correlation between body weight versus scrotal circumference, testicular weight, testicular volume and GSI. However, age did not have a positive association with percentage of normal sperm in Arabian oryx. Conclusively, the current findings provide a valuable data for future use of artificial insemination, which will be crucial for propagation and conservation of Arabian oryx.