Evaluation of foal production following intracytoplasmic sperm injection and blastocyst culture of oocytes from ovaries collected immediately before euthanasia or after death of mares under field conditions.

The research evaluates the effectiveness of producing foals using intracytoplasmic sperm injection (ICSI) and blastocyst culture from the ovules of mares that were either euthanized or died naturally.

Research Methodology

• The study is a prospective case series involving 16 mares aged between 3 and 19 years that had either died or were euthanized due to various reasons.
• The ovaries were collected immediately before euthanasia or after death, transported to a laboratory for oocyte recovery, or in the case of one mare, the oocytes were extracted remotely and then shipped to the laboratory.
• The recovered oocytes underwent ICSI, a process which involves injecting a single sperm directly into an egg. Following this, the presumptive zygotes were cultured for a period of 7 to 10 days.
• The resulting blastocysts were then shipped to embryo transfer facilities for transcervical transfer to recipient mares.

Key Findings

• Ovaries were processed between 30 minutes and 12 hours after the mares’ death. On average per mare, 14.1 ± 8.6 oocytes were cultured, of which about half matured.
• ICSI resulted in the development of 21 blastocysts which were transferred to recipient mares. These transfers produced 13 pregnancies, from which 10 healthy foals were born.
• The study found a significant correlation between the number of oocytes recovered, the number of blastocysts produced per mare, and the number of live foals produced per mare.

Conclusions

• The study concluded that it is feasible to produce foals after the death or euthanasia of a mare under field conditions using ICSI and blastocyst culture.
• In terms of proportions, the research reported that greater numbers of foals were born overall (10 foals from 16 mares), and from the mares from which at least one foal was produced (6 out of 16), as compared to what was achieved with the recovery and oviductal transfer of oocytes to inseminated recipients after the death of donor mares under field conditions.