Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

This research aimed to determine the link between Thoroughbred broodmare’s weight and endocrine function, and the birthweight of their foals. It was found that obese mares gave birth to heavier foals, although the study did not identify significant fasting hyperinsulinaemia in this mare population. A key finding is that higher leptin concentrations during early and late pregnancy correlated with lower foal birthweights.

Study Overview

• This research was a prospective cohort study involving 57 pregnant Thoroughbred mares.
• The primary objective of the study was to investigate the association between mare obesity or endocrine dysfunction and foal birthweight.
• To achieve this objective, the body condition scores (BCS), weight, and venous blood samples of the mares were recorded every 60 days throughout the duration of the gestation period.
• Serum and plasma insulin, leptin and triglyceride concentrations were measured using standard methods and correlated with the BCS and birthweight of the foals.
• A linear mixed effects model was used for the association analysis.

Key Results

• There was a significant fluctuation in the serum insulin concentrations at different gestation periods, although there was no clear association of fasting insulin concentration with mare’s BCS.
• 55% of the mares in the study had a BCS of 7 or more, which in horse body condition scores equates to being overweight.
• Leptin concentration was significantly higher at 180-239 days gestation when compared to all other time points and was positively correlated with mare’s BCS.
• There were significant higher triglyceride concentrations at 240-299 days gestation when compared to earlier time points, but this did not associate with mare’s BCS.
• Foal birthweight was found to be positively correlated with mare’s BCS, indicating that heavier mares had heavier foals.
• Interestingly, leptin concentrations during early and late gestation showed an inverse relationship with foal birthweight, suggesting that increased leptin could predict decreased foal birthweight.

Conclusions

• The study concludes that there is a correlation between mare’s BCS (specifically obesity) and foal birthweight with heavier mares producing heavier foals.
• Contrary to expectations, the presence of fasting hyperinsulinaemia was not identified in the studied population.
• The research points towards the potential of using leptin concentration in mares, specifically in the early and late stages of gestation, as a predictor for foal birthweight.
• Further research is required to confirm these findings and their applications in the equine breeding industry.