Effects of the Addition of Autologous Seminal Plasma to Highly Concentrated Stallion Semen After 48 Hours of Cooled Storage

Efficiency of Ringer B. Braun solution on stallion epididymal sperm motility and viability compared to the commercial extender within 72 hours of storage

Collection of epididymal stallion sperm offers the opportunity to retain and use genetic material from the males after elective castration or even post mortem. The aim of the present study was to evaluate the effect of the Ringer B. Braun solution on stallion epididymal sperm viability and motility during liquid storage for 72 h at 4 °C and at 20 °C. Eight stallions (3–10 years old) were used in the study. Sperm from the cauda epididymis was harvested immediately after routine castration. The sperm from epididymis was washed out and diluted with Ringer B. Braun solution and with a commercial semen extender which was used as a control. Samples from each horse were divided into two parts: one part of samples was stored at 4 ± 1 °C as recommended for the commercial semen extender, the other one was stored at 20 ± 1 °C. Sperm viability, motility, and pH were checked one hour after collection and dilution, and after 24, 48 and 72 h of incubation. The results of sperm viability, subjective and progressive sperm motility showed slightly higher results in semen samples diluted with Ringer B. Braun solution in one hour compared to the commercial extender, by 2.40 ± 0.49% for viability (P > 0.05), by 0.30 ± 9.92% for subjective motility (P > 0.05) and by 5.70 ± 6.07% for progressive motility (P > 0.05). We suggest that Ringer solution could be used for a short term storage (1–24 h) of equine epididymal semen at a 4 °C temperature.

Supplementation of cauda epididymal plasma improves sperm characteristics following liquid preservation of ram semen at 3-5°C

Mammalian spermatozoa remain immotile and metabolically inactive in the cauda epididymidis, thus maintaining fertility for several weeks. The aim of this study was to functionally characterise and evaluate the effect of cauda epididymal plasma (CEP) on liquid preservation of ram spermatozoa. Four experiments were conducted to investigate the effects of: (1) CEP and its fractions on sperm motility; (2) CEP (10%, 15%, 20% v/v) on liquid preservation of ram spermatozoa; (3) seminal plasma (SP; 20%, 30%, 50% v/v) on liquid-preserved spermatozoa; and (4) both CEP and post-storage SP treatment on sperm characteristics. Biochemical characterisation of ram CEP revealed high protein (30.9mgmL-1), catalase (68.9IUmL-1), alkaline phosphatase (17.5IUmL-1) activities and total antioxidant capacity (1112µM Trolox equivalent). Progressive motility of prewashed cauda spermatozoa was reduced (P<0.05) by CEP or its protein-rich fraction compared with protein-free plasma or phosphate-buffered saline. After 48h storage, total motility, rapid motility (average path velocity >75µms-1; 53.9%, 73.5% and 71.8% with 0, 15% and 20% CEP respectively) and straight line velocity (86.3, 102.1 and 102.4µms-1 with 0, 15% and 20% CEP respectively) were significantly (P<0.05) higher in the CEP-treated groups than the control. Viability and acrosomal integrity were similar between groups; however, functional membrane integrity was higher (P<0.05) in the 15% CEP-treated group. Treatment of liquid-preserved spermatozoa with either 20%, 30% or 50% SP improved (P<0.05) rapid motility and kinematics at each time point of storage compared with control. In conclusion, liquid preservation of ram spermatozoa in the presence of 15% or 20% CEP and post-storage treatment with SP significantly improve sperm characteristics.

Postthaw Addition of Autologous Seminal Plasma Improves Sperm Motion Characteristics in Fair and Poor Freezer Stallions

During semen processing for cryopreservation, most seminal plasma is usually removed, and components with protective effects on sperm may be missing after thawing and within the female reproductive tract. The present study evaluated the effect of postthaw addition of autologous seminal plasma on motion characteristics of stallion sperm with fair (n = 4) or poor (n = 3) freezability. Therefore, pure seminal plasma (group SP1), seminal plasma combined with fresh semen extender (group SP2), or seminal plasma mixed with freezing extender (group SP3) were used to fill 0.5 mL straws and frozen similar to stallion semen. Postthawing, semen samples (n = 42) were diluted either with semen extender (group FT) or with seminal plasma (n = 126) of groups SP1 to SP3 to 25 × 10⁶ sperm/mL. In fair freezer stallions, total and progressive motilities were higher in group FT than in group SP1 (P < .05), but there was no difference in poor freezing stallions among groups (P > .05). However, comparing individual stallions, positive effects of seminal plasma on total or progressive motility were detected in two stallions. Curvilinear velocity increased in groups SP2 and SP3 in fair freezer stallions and in all groups with seminal plasma compared with group FT in poor freezer stallions (P < .05). Although straightness was higher in groups SP2 and SP3 compared with group FT in fair freezer stallions (P < .05), there was no difference among groups in stallions with poor freezability (P > .05). Average lateral head displacement did not change among groups of fair freezer stallions (P > .05) but was higher in groups SP2 and SP3 than in group FT in poor freezer stallions (P < .05). Beat cross frequency was higher in all groups diluted with seminal plasma postthawing in fair freezer stallions (P < .05), but only in group SP1 than in group FT in poor freezer stallions (P < .05). The addition of autologous seminal plasma to frozen-thawed semen can improve motion characteristics of stallions with fair and poor freezability. This is a valuable additional protocol for laboratories dealing with cryopreservation of stallion semen and for veterinarians working with fair or poor freezer stallions.