Effects of tris–egg yolk and OptiXcell® extenders on post-thaw spermatological parameters in goat semen

Abstract

Objectives: The objective of this study was to comparatively evaluate the post-thaw sperm quality of Boer and Anglo-Nubian goats using semen samples in which seminal plasma was removed by centrifugation and subsequently diluted with a Tris-based egg yolk extender, or directly diluted with the commercial liposome-based extender OptiXcell® without prior centrifugation. Materials and Methods: Semen samples were collected from five adult Boer and five adult Anglo-Nubian goats using an artificial vagina. Collections were performed once weekly over a five-week period, resulting in five replicates per animal. The collected semen samples were divided into two equal portions. The first portion was centrifuged to remove seminal plasma prior to dilution with a Tris–egg yolk (TEY) extender (Boer-TEY and Anglo-Nubian-TEY), whereas the remaining portion was directly diluted with OptiXcell® (Boer- OptiXcell and Anglo-Nubian- OptiXcell). Twenty-five samples per group were individually cryopreserved, and post-thaw evaluations were performed. Sperm motility parameters were assessed using computer-assisted sperm analysis (CASA), while plasma membrane integrity, acrosome integrity, mitochondrial activity, viability, and reactive oxygen species (ROS) levels were evaluated by flow cytometry. Results: Post-thaw CASA analysis revealed that total motility (MOT, %) was significantly higher in Boer goat spermatozoa diluted with the TEY extender compared to those diluted with OptiXcell® (p<0.05). However, MOT values in the Boer–TEY group did not differ from those in the Anglo-Nubian TEY or Anglo- Nubian OptiXcell® groups (p>0.05). Progressive motility (%) and all velocity-related kinematic parameters (VAP, VSL, VCL, ALH, BCF, STR, LIN, and WOB) showed no significant differences among groups (p>0.05). Flow cytometric assessments indicated no significant differences in plasma membrane integrity (%), acrosome integrity (%), high mitochondrial activity (%), or viability (%) between groups (p>0.05). In contrast, the proportion of spermatozoa with intracellular reactive oxygen species (ROS) was significantly lower in Boer goat spermatozoa diluted with the TEY extender (p<0.05) Conclusions: Breed variation should be considered when selecting extenders for goat semen cryopreservation. In Boer goats, the Tris–egg yolk extender was found to be more effective for semen cryopreservation compared to the OptiXcell® extender.