Comparison of Various Extenders for Storage of Cooled Stallion Spermatozoa for 72 Hours

Multiple extenders have been developed to preserve cooled stallion semen. Comparisons of some extenders have been made but there is need for further research in this area. Extenders tested included EZ Mixin (Animal Reproduction Systems, Chino, CA), Kenney's, Universal (NASCO, Fort Atkinson, WI), EquiPro, EquiPro CellGuard (Minitube of America, Verona, WI), and INRA 96 (IMV, Maple Grove, MN). Semen was collected and each ejaculate was divided and extended in each of the aforementioned extenders and stored at 4°C. Motility measures were determined using computer-assisted sperm analysis at 0, 24, 48, and 72 hours after collection. Samples were evaluated for total motility, progressive motility (PM), straight-line velocity, curvilinear velocity, straight-line distance, and curvilinear distance. Total motility and PM decreased over time in storage (P < .05). Sperm stored in INRA 96, EquiPro, and EquiPro Cell Guard retained the most total motility and PM over the 72 hour period (P < .05). Universal, EquiPro, and EquiPro Cell Guard had the highest measurements for curvilinear velocity, straight-line velocity, and curvilinear distance (P < .05). There were no significant differences among the extenders for straight-line distance.