Epididymal Semen Harvesting
The latest pioneering method of semen recovery
Post castration epididymal semen extraction is a pioneering method of semen collection that permits semen extraction where other options don’t allow. Referring to the removal of semen from the epididymis of the testes, the procedure can be used following routine castration, upon death of the animal or where the testes have suffered a severe trauma or torsion; the latter unplanned terminal/traumatic situations the pinnacle of its use.
When should it be used?
In ordinary circumstances, valuable breeding stallions have semen collected and frozen during periods of competing rest, or when fresh breeding programmes have concluded. However, if this is not possible, and when stallion death is sudden and unanticipated, semen can now be salvaged and frozen retrospectively via epididymal semen extraction.
The Epididymis- a valuable hub of semen
The epididymis is a long, highly convoluted tubular duct that lies alongside the testes (figure 1). Consisting of a head, body and tail, the epididymis acts as a storage area and site of final maturation of sperm cells prior to ejaculation.
At any point, up to 62% of sperm cells in the epididymal duct can be found in the tail of the epididymis, providing a significant reservoir of potentially fertile semen that can be harvested post castration of the stallion.
What happens during epididymal semen extraction?
For the procedure, the stallion has one or both testes removed using standard castration techniques. The testicles are then shipped on a same day basis to the semen collection centre. A complex 4-hour extraction procedure follows to harvest and preserve the valuable semen within the epididymis.
Is semen always recovered from the testes?
Post castration epididymal semen extraction is not a guaranteed method of semen recovery. Unfortunately, there will be a proportion of stallions for which the procedure will be unsuccessful due to stallion related issues, circumstances at point of death or issues during testicle removal and transit. However, for sexually mature, reproductively normal stallions, the procedure has a high percentage recovery rate providing correct castration methods and shipping timescales are met.
How Many doses are recovered?
The amount of semen recovered from the testes is highly variable between stallions and dependent upon numerous factors related to the stallion, the conditions around the castration and testicle handling post removal. However, on average for reproductively normal and sexually mature stallions, the total dose number recovered ranges from 10-60 doses.
Semen quality
Semen quality is usually good for reproductively normal stallions but is dependent upon the stallion’s inherent semen quality prior to the procedure. Fertility rates can be lower with epididymal semen versus ejaculated semen due to lack of exposure of the sperm cells to components of a regular ejaculate. At SAIS, the use of our world leading semen freezing extender helps to mitigate the effects of this.
Epididymal Semen Extraction and Intra cytoplasmic Sperm Injection (ICSI)
As technologies progress and become more accessible, Intra-Cytoplasmic Sperm Injection (ICSI) may be the preferred method of use for epididymal semen. The procedure requires only one sperm cell to be injected into an oocyte and therefore helps to conserve sperm banks. When using ICSI, epididymal semen produces the same pregnancy rates as ejaculated frozen semen.
Health testing
Standard pre-breeding health tests apply to stallions undergoing post castration epididymal semen extraction. Health tests for Equine Infectious Anaemia (EIA), Equine Viral Arteritis (EVA), Contagious Equine Metritis (CEM), Klebsiella and Pseudomonas must be carried out in accordance with the semen collection centre recommendations (Link to document).
Further information
For further information on the procedure or to request use of the service, please contact us
(RBST Collaboration link?)
