The effect of uterine massage and number of embryo flushing attempts on embryo recovery in mares.

This study investigates how the technique and frequency of embryo flushing in mares can influence the successful recovery of embryos. It was found that uterine massage yielded higher embryo recovery rates, with most embryos recovered on the first flushing attempt.

Study Methodology

• The researchers used 10 non-lactating mares for their study, which each underwent six insemination cycles, resulting in a total of 60 cycles for analysis.
• Three operators with varying levels of experience performed the embryo flushing 7-9 days after the mares had ovulated. One operator had performed over 500 embryo flushings prior to the study (OP1), while the other two had no prior experience.
• The flushing was done twice per cycle, using one liter of a saline solution (Ringer’s Lactate) each time. This was administered using two different techniques: uterine massage (UM) involving physical manipulation of the uterus through the rectum, and gravity flow(GF) in which the saline was allowed to drain naturally without physical intervention.
• In both methods, 20 IU of oxytocin were given during the second flush, and the saline was left in the uterus for three minutes before drainage.
• An additional flushing attempt was made using half the amount of saline and the uterine massage approach.

Study Results

• Results showed that more embryos were recovered using the uterine massage technique (17 out of 33 or 51%), as opposed to gravity flow (8 out of 36 or 22%).
• In the UM group, 94.1% of embryos were recovered on the first flush, while only 5.9% were recovered on the second flush. The GF group had an even split, with half the embryos recovered on the first flush and the other half on the second.
• No embryos were found during the extra flushing attempt in the UM group, but seven were discovered during this step in the GF group. Of these, five were retrieved by the experienced operator (OP1).
• The overall success rates per cycle for the different operators were significantly varied, with OP1 achieving a 70% success rate, compared to 40% and 45% for OP2 and OP3 respectively.

Conclusion

• The researchers concluded that the uterine massage technique led to higher rates of successful embryo recovery. The majority of embryos were recovered during the first flushing attempt, even with operators of varying experience levels.