Is there a Seminal Plasma Impact on Foal Growth?

Seminal Plasma Impact on Foal Growth - image shows two cartoon foals of different sizes with partially-filled test tubes surrounding themThis study investigated the downstream developmental consequences of seminal plasma (SP) exposure — or its absence — at the time of breeding, examining both placental gene expression and seminal plasma impact on foal growth trajectories over the first two years of life.

Background & Purpose:

  • SP proteins serve key immunomodulatory roles at breeding: SP DNAse suppresses neutrophil extracellular traps (NETs); CRISP-3 and lactoferrin/SOD-3 balance sperm protection with pathogen clearance
  • Prior work identified SP-associated DEGs in the endometrium linked to embryo development, immunotolerance, and metabolism
  • Parallels with human ART outcomes motivated the hypothesis that SP absence disrupts the uterine environment and offspring health

Experiment 1 — Placental Transcriptomics:

  • Warmblood mares: SP-exposed (n=9) vs. ICSI-produced embryo recipients (n=9; no SP)
  • Chorioallantoic RNA sequencing performed post-partum
  • 1,580 genes differentially expressed (FDR p<0.05)
  • KEGG pathway disruptions identified in: hypoxia signaling, metabolism, innate immunity, angiogenesis (EGF/EGF bypass), and translational regulation (eIF-4E, DROSHA)

Experiment 2 — Foal Growth Monitoring:

  • 60 foals monitored monthly for 24 months: SP-exposed (n=30) vs. no SP (embryo transfer/ICSI; n=30)
  • Foals without SP exposure showed significantly greater weight gain over two years (p<0.05), most pronounced in colts
  • Accelerated growth raises concern for osteochondrosis dissecans (OCD) and other developmental orthopedic diseases

Conclusions:

  • Absence of seminal plasma at breeding associates with placental transcriptomic dysregulation and has an impact on foal growth
  • Findings carry significant implications for commercial use of ICSI and embryo transfer in equine reproduction

(Troedsson MHT, Scoggin KE, El-Sheikh Ali H, Fedorka CE. 2025. Seminal plasma (SP) exposure during breeding alters placental transcriptome and subsequent growth of foals. JEVS 145:105329 – Presented in Association with and by Permission of the International Society for Equine Reproduction)