Homologous seminal plasma efficiently activates epididymal tail sperm compared to traditional tris buffer and sperm-TALP in sheep

We hypothesized that ram epididymal tail sperm may be efficiently activated in homologous seminal plasma compared to tris and sperm-TALP. Eighty ejaculates were collectedfrom five healthy fertile rams by artificial vagina. Ejaculates with ≥ 3 mass motility and ≥ 70% initial motility score were considered and pooled. The seminal plasma was harvested by two-phase centrifugation (A-3000 g, 4 °C, 20 min; B-3600 g, 4 °C, 30 min). Sperm were collected by dissecting epididymal tail into 3 equal parts which were placed in three small (35 mm) petri dishes for activation in homologous seminal plasma (SP), sperm-TALP (TP) and tris buffer (TR). Sperm quality was assessed at 0, 24, 48 and 72 h of cold storage on the basis of motility, viability, HOST and acrosomal integrity. In addition to subjective assessment of motility, acrosomal integrity and viability were evaluated using molecular florescent probe combinations-fluorescein isothiocyanate (FITC) conjugated to peanut agglutinin (PNA) plus propidium iodide (PI) and carboxyflorescene diacetate (CFDA) plus propidium iodide, respectively. Motility, CFDA positive sperm (Viable) and HOST reacted sperm percentage were significantly higher (p < 0.05) for SP compared to both TP and TR at 48 and 72 h of cold storage. FITC-PNA negative sperm (Intact acrosomes) percentage did also differ significantly (p < 0.05) between SP, TP and TR at various hours of cold storage. In conclusion, homologous seminal plasma efficiently activated and preserved epididymal tail sperm compared to tris buffer and sperm-TALP. This study provides an opportunityto further explore the role of homologous seminal plasma in cryoprotection and fertilizing capacity of epididymal tail sperm.