Improved embryo recovery through increased flushing media volume and the impact on unintended pregnancies in a single subject donor mare.

This research is about a method to improve recovery of embryos from horses (mules) by using larger volumes of flushing media during a procedure called embryo flushing (EF), subsequently reducing unexpected pregnancies. The study tested the method on a single non-lactating Spanish purebred mare over a period of two years.

Initial Experiments – Group 1

• The initial phase comprised six EF experiments conducted on the mare, using 1L of a flushing medium known as Ringer´s Lactate.
• No Prostaglandin F2-alpha (PGF2α) was administered after every EF procedure. PGF2α is often used to terminate pregnancies in mares.
• The frequency of double ovulations (OV) in these initial experiments was 33.3%. Double OV refers to the release of two eggs from the ovaries in a single menstrual cycle, which was not affected by the volume of the flushing medium.
• These tests resulted in an embryo recovery rate of 25%, demonstrating that 1 in every 4 attempts was successful in obtaining an embryo.
• A significant number of unintended pregnancies was also recorded in this group (4 out of 8 attempts).

Subsequent Experiments – Group 2

• A second group of tests was carried out involving five EF procedures. This time, the volume of the flushing medium was doubled to 2L, and no PGF2α was given post-procedure, mirroring conditions of the first experiment.
• This change resulted in a frequency of double OV of 40%, affirming the earlier finding that this rate remained unaffected by the flushing medium used.
• The embryo recovery rate, however, showed a marked improvement from the initial 25% to an impressive 85.7% – more than 3 in every 4 attempts were successful.
• Additionally, all EF procedures led to a positive outcome in this group (100% success rate).
• Contrary to the results of the first group, no unintended pregnancies were recorded in this set of tests.

Conclusion

• The study showed that increasing the volume of the flushing medium during EF significantly improves the embryo recovery rate.
• It also helps to reduce the number of unintended pregnancies in the mares.
• Thus, it suggests that the volume of the flushing medium plays a critical role in obtaining a higher recovery of embryos and controlling undesired pregnancies in mares.