Skip to Main Content

The Effect of Egg Yolk in Freezing Extender on Equine In Vitro Fertilization Rates

Amy Boyer, J. Cohen, DD Varner, and K. Hinrichs

Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA

Amy Boyer Picture


Objective- This study was conducted to evaluate the effect of egg yolk in freezing extender on equine in vitro fertilization rates.

Animals or Sample population- No live animals were used directly in this experiment.

Procedure- Horse semen from one ejaculate was frozen using two different extenders, MFR5 with egg yolk and MFR5 with no egg yolk.  Horse oocytes were collected from ovaries obtained from slaughtered mares.  The oocytes were matured in vitro before being added to the fertilization droplets.  Sperm was prepared for IVF using a swim-up procedure and was treated with heparin before placement in fertilization droplets.  After sperm were added, the fertilization droplets were incubated for 36 hours at 38.2ºC and 5% CO2.  The oocytes were then stained using Hoechst 33258 and examined under a fluorescent microscope to assess fertilization.

Results- Three replicates were performed.  No oocytes in the egg yolk treatment were fertilized.  One oocyte in the no egg yolk treatment was fertilized.

Conclusions and Clinical Relevance- Freezing semen with no egg yolk in the extender does increase equine in vitro fertilization rates with the IVF protocol used.