Storage Conditions Affecting Prolonged Storage of Post-thaw Semen

Prolonged Storage of Post-thaw Semen - image of semen samples on the lab counterField-based use of cryopreserved stallion semen is often limited by the equipment and expertise required for on-site thawing. Thawing centrally, then achieving prolonged storage of post-thaw semen and shipping it in a cooled state could simplify artificial insemination programs at locations remote from the laboratory or center, but optimal post-thaw storage conditions remain poorly defined.

Study Design:

  • Frozen semen from 5 Warmblood stallions; 3 repetitions per stallion
  • Thawed at 38°C for 20 seconds; diluted to 50 million sperm/ml; stored for 72 hours
  • Four treatment groups:
    • EquiPlus extender stored at 5°C
    • SperVital White Cap extender stored at 5°C
    • Beyond extender stored at 5°C
    • Beyond extender stored at 17°C
  • Total motility, progressive motility, and membrane integrity assessed every 24 hours by computer-assisted sperm analysis

Key Results:

  • All parameters declined significantly over time across all groups
  • EquiPlus and SperVital significantly outperformed Beyond for motility and membrane integrity, regardless of storage temperature
  • Total motility at 48 hours: EquiPlus 22%, SperVital 23%, Beyond at 5°C 13%, Beyond at 17°C 18%
  • Storage temperature (5°C vs. 17°C) had no significant advantage for Beyond extender

Conclusions:

  • Frozen-thawed stallion semen can maintain viable motility and membrane integrity for up to 72 hours post-thaw under appropriate conditions
  • Extender composition is the primary determinant of post-thaw storage quality, outweighing temperature effects
  • Further research into sperm metabolism is needed to optimize prolonged storage of post-thaw semen and post-thaw shipping protocols for artificial insemination programs

(Bernardi L, Schreiner B, Rizzo A, Monaco D, Aurich C. (2025) Storage conditions influence the maintenance of frozen-thawed stallion semen characteristics if stored for a prolonged period. JEVS 145:105267 – Presented in Association with and by Permission of the International Society for Equine Reproduction)