Effect of insemination time of frozen semen on incidence of uterine fluid in mares.

This research paper discusses a study that investigated how the timing of artificial insemination (AI) with frozen semen affects the incidence of uterine fluid accumulation in mares. The findings suggest that the timing of AI, whether pre-ovulatory or post-ovulatory, does not significantly impact the overall pregnancy rate, nor the presence of uterine fluid.

Research methodology

The researchers used a sample group of ninety-five mares, which received artificial insemination with frozen semen at different times around ovulation. The study employed two timing models:

• Mares inseminated within 12 hours before ovulation
• Mares inseminated within 8 hours after ovulation

Results

On inspecting the mares 12 hours after AI, 35% were found to have accumulated uterine fluid. However, when examined 18 to 24 hours after AI, only 14% exhibited uterine fluid. These observations showed:

• The presence of intrauterine fluid significantly lowered the pregnancy rates.
• The timing of insemination (either before or after ovulation) did not affect the emergence of uterine fluid.
• There was no significant difference in pregnancy rates between preovulatory and postovulatory inseminations.

Impact of hormone concentrations on pregnancy

The levels of estrogen and progesterone at the time of insemination were considered to see if they influenced uterine clearance or pregnancy rates. Interestingly:

• Both hormones exhibited higher levels during preovulatory than postovulatory inseminations.
• Despite this fluctuation, the hormones’ concentrations did not appear to significantly affect uterine clearance or pregnancy rates.

Final conclusions

The findings of this study showed no evidence demonstrating that postovulatory inseminations would predispose mares to persistence of uterine fluid after AI. Instead, the authors suggest that the presence of intrauterine fluid itself correlates with lower pregnancy rates. This directly implies that the timing of insemination did not play a significant role in the incidence of uterine fluid or the overall success of pregnancies within the study group.