Factors concerning early embryonic death in thoroughbred mares in South Korea.

The research investigates factors causing early embryonic death in thoroughbred mares in South Korea, with findings suggesting that age, breeding condition, uterine health, and timing of mating significantly influence the likelihood of embryonic death.

Methodology

• The researchers examined 384 Thoroughbred mares across nine equine farms on Jeju Island, South Korea, for a period of three years (2001 to 2003).
• The mares were mated 771 times during this period, with the success of breeding determined 15 days after ovulation. At this point, 376 successful pregnancies were identified.

Findings

• Of the 376 successful pregnancies, 46 (or 12.2%) subsequently resulted in early embryonic death within 45 days after ovulation.
• Of the 46 embryonic deaths, the majority (approximately 75%) occurred between 16 and 25 days post-ovulation.
• Mares over 15 years old, barren, or with more than 10 parities (births) had an increased rate of embryonic death compared to their counterparts.

Conditions and Timings Affecting the Incidence of Embryonic Death

• Mares mated in March and April, along with those mated during the first estrus following birth, had elevated rates of embryonic death.
• Mares with abnormal uterine fluid, cysts in the uterus, or multiple embryonic vesicles also had higher embryonic death rates.
• It was determined that the health and breeding conditions of the mares, along with the environment of the embryo or fetus, are primary factors affecting early embryonic death.

In conclusion, this study highlights multiple factors affecting the incidence of early embryonic death in thoroughbred mares, critical for improving breeding efficiency and reproductive health in these animals. Future research could focus on developing strategies to mitigate these factors and reduce the rates of early embryonic death in thoroughbred mares.