A comparative study across mule, equine and equine clone pregnancies regarding the determination of the day of birth.

Overview

• This study compared different physical and biochemical markers in pregnant mares carrying mule, equine, or equine clone fetuses to improve prediction of the exact day of birth (parturition).
• The research aimed to understand if established indicators like vulvar relaxation, ligament tension, mammary secretion pH, and electrolyte levels differ between these groups to enhance foaling prediction accuracy.

Background and Importance

• Effective monitoring of mares before foaling is critical for timely interventions during birth complications and for ensuring health of mares and foals.
• Challenges exist in monitoring due to differences in gestation length and the frequent occurrence of nighttime births which complicate timely observations.
• Predictive methods for foaling could reduce labor intensity and costs on breeding farms by focusing monitoring efforts during critical periods.
• There is limited research on foaling prediction in mares carrying mule or cloned equine fetuses compared to typical equine pregnancies.

Study Objective

• The main goal was to analyze and compare various physical signs and biochemical parameters in mares pregnant with:
• Mule fetuses (MF)
• Equine clone fetuses (CF)
• Equine control fetuses (EF)
• Parameters assessed included vulvar relaxation, tension in the sacroiliac ligament, mammary secretion pH, BRIX index (a measure related to colostrum), and mineral electrolyte concentrations (calcium, phosphorus, magnesium, sodium, potassium).

Methodology

• Sixty pregnant mares were divided into the three groups: 25 with mule fetuses, 20 with equine clone fetuses, and 15 with control equine fetuses.
• Physical signs were observed, and mammary secretions were collected in the days leading up to and including parturition.
• Laboratory analyses measured pH, BRIX values, and concentrations of key electrolytes in mammary secretions.
• Statistical analyses were performed to detect significant differences within and between groups over time.

Key Findings

• Vulvar relaxation and sacroiliac ligament tension:
• Significant increases in these physical signs were seen only in the mule fetus group on the day of parturition, indicating they may be reliable for predicting foaling specifically in MF pregnancies.
• No significant changes in these signs appeared in the clone or control equine groups around birth.
• Mammary secretion pH:
• pH levels decreased significantly on the day of parturition across all groups, indicating increased acidity linked to imminent birth.
• Lower pH values were noted in MF (around 6.05) and CF (around 6.08) compared to EF (around 6.26), suggesting differences linked to fetus type.
• A consistent trend of decreasing pH closer to foaling was observed, making this a potentially useful predictive marker.
• BRIX index:
• This index varied widely among mares and did not correlate well with proximity to foaling.
• The BRIX index may be better suited for assessing colostrum quality rather than predicting the timing of birth.
• Electrolyte concentrations (Ca, P, Mg, Na, K):
• Electrolytes generally correlated with impending parturition but did not significantly differ between groups.
• Calcium showed notable increases in the days before foaling especially in MF (102% increase) and CF (110%) groups compared to EF (38%).
• Phosphorus demonstrated a pattern similar to calcium, suggesting it could be a novel parameter worth further investigation for foaling prediction.

Conclusions and Implications

• Physical signs like vulvar relaxation and ligament tension may be good foaling indicators for mares carrying mule fetuses but are less reliable in clone or standard equine pregnancies.
• Mammary secretion pH is a promising universal biochemical marker, with lower and falling pH values signaling imminent birth across all groups.
• The BRIX index should not be used for predicting foaling timing but remains useful for evaluating colostrum quality post-birth.
• Electrolyte monitoring, especially calcium and phosphorus, might help identify approaching parturition, but further research is needed to validate phosphorus as a predictive marker.
• This comprehensive comparative study highlights the physiological differences in pregnancies involving mule and cloned fetuses versus normal horses and could guide breeders toward more tailored and cost-effective foaling monitoring strategies.