Effects of Different Diluents on Semen Quality of Hu Ram Stored at 4 °C

SIMPLE SUMMARY: Diluent plays an important role in sperm storage. The various components of the diluent provide nutrition for sperm survival, maintain the stability of the preserved environment, and prolong the survival time of sperm. However, for the preservation of semen at 4 °C, diluent formulations are currently lacking or existing diluent formulations are not sufficient. Therefore, the effect of four diluents on semen preservation was studied through an assessment of sperm motility and functional integrity. Diluent D (Tris–Fructose–Citric acid–Egg yolk) was found to greatly improve semen quality during storage at 4 °C. ABSTRACT: This study aimed to investigate the effects of various diluents on the quality of Hu ram sperm stored at 4 °C. Semen samples were collected from three Hu rams and diluted with diluents A (Sodium citrate–Glucose–Egg yolk), B (Sodium citrate–Glucose), C (Fructose–Skimmed milk powder–Soy lecithin), and D (Tris–Fructose–Citric acid–Egg yolk). Total motility (TM), straight-line velocity (VSL), average path velocity (VAP), curvilinear velocity (VCL), average motion degree (MAD), acrosome integrity, membrane integrity, and reactive oxygen species (ROS) were evaluated. The results showed that diluent D had better preservation in terms of the sperm TM, VSL, VCL, VAP, MAD, and membrane and acrosome integrity. On the third day of the storage, the sperm PM of diluent D was higher than that of other diluents (p < 0.05). The ROS level of diluent D was lower than that of other diluents on the fifth day (p < 0.05). On the seventh day of the storage, the sperm TM in diluent D reached 50%, which was the highest in all diluent groups. On the seventh day of the storage, the integrity of the sperm membrane and the integrity of the acrosome of the sperm in diluent D were the highest in all diluent groups (p < 0.05). In conclusion, these results indicated that diluent D improved the semen quality during storage at 4 °C. In this study, diluent D was the best diluent formula for Hu ram semen stored at 4 °C.