Post-Thaw Sperm Quality and Blastocyst Production Following Intracytoplasmic Sperm Injection in Mares

Post-thaw sperm quality effect on ICSI outcome is well-recognized, and this research reviewed correlations with possible clinically applicable screening criteria assessable in standard laboratory settings.

Post-Thaw Sperm Quality Effect on ICSI - blastocyst and sperm vialsBackground:

  • Intracytoplasmic sperm injection is widely used to maximize semen availability from stallions with limited supply
  • The relationship between standard frozen/thawed sperm quality measures and embryo production via intracytoplasmic sperm injection remains poorly characterized

Study Design:

  • Frozen/thawed semen from 44 stallions analyzed in a commercial intracytoplasmic sperm injection program
  • Sperm assessed before and after swim-up selection for: total and progressive motility (subjective and computer-assisted), morphology, and DNA damage
  • 485 in vitro-matured oocytes from 59 mares injected across 85 transvaginal aspiration cycles
  • Stepwise logistic regression used to identify predictors of cleavage and blastocyst production

Program Efficiency:

  • In vitro oocyte maturation rate: 64%
  • Cleavage rate at day 5: 62%
  • Blastocyst rate per injected oocyte: 29%
  • Blastocyst rate per cleaved oocyte: 46%
  • Total blastocysts produced: 139 (1.64 per session)

Key Results:

  • Positive predictors of blastocyst production:
    • Higher total motility before swim-up (subjective and computer-assisted)
    • Higher percentage of morphologically normal spermatozoa
  • Negative predictors of blastocyst production:
    • Proximal cytoplasmic droplets after swim-up
    • Coiled tails before swim-up
    • Elevated sperm chromatin structure assay fragmentation index before swim-up
  • No single parameter predicted cleavage rate

Conclusions:

  • Pre-swim-up motility and normal morphology are the strongest positive indicators of intracytoplasmic sperm injection success
  • Sperm structural defects and DNA damage are significant negative predictors
  • Post-thaw sperm quality effect on ICSI is well-recognize and findings provide clinically applicable screening criteria assessable in standard laboratory settings

(Hernandez-Aviles C, Love CC, Ramirez-Agamez L. 2025. The relationship between post-thaw sperm quality and blastocyst production following Intracytoplasmic Sperm Injection (ICSI) of in vitro-matured equine oocytes. JEVS 145:105293 – Presented in Association with and by Permission of the International Society for Equine Reproduction)