The effect of rectal palpation on the fertility of cyclic mares.

This study examines the impact of rectal palpation on the fertility of non-lactating, normally cycling mares over a period of three years, finding varied results, but notably a lowered first-cycle conception rate for palpated mares when inseminated with undiluted semen.

Study Methodology and Year One Findings

• The research took place over three years, during which the researchers performed daily rectal palpations on mares either only during oestrus, a period in their reproductive cycle, or during oestrus and the first 50 days of their pregnancy.
• In 1971, the first year of the study, researchers found that the conception rates were not significantly lower for the palpated mares compared to the mares which were not palpated. Additionally, no abortions were found to be a result of the palpation.
• Interestingly, researchers also found that oestrus lasted longer in mares that were not palpated.

Year Two Findings

• In the second year, daily palpation during oestrus resulted in lower first-cycle pregnancy rates among the palpated mares when compared to those that were not palpated.
• When palpation was combined with insemination based on the palpator’s advice, it resulted in fewer inseminations per cycle as compared to mares that were inseminated every other day of oestrus.

Year Three Findings

• During the third and final year of study, the difference in first-cycle conception rates between the mares palpated every other day of oestrus and the ones not palpated was not significant statistically.
• However, when viewing the entirety of the three-year study, researchers found that mares not palpated had higher first-cycle conception rates following insemination with undiluted semen compared to the palpated mares.

Conclusion

• The study thus suggests that rectal palpation might have an impact on the conception rates of mares, particularly when insemination is performed with undiluted semen. However, the significance of this difference varies based on the frequency of palpation and the period of palpation (during oestrus or throughout the early stages of pregnancy).