Plasma melatonin concentration during the early post-partum period in Thoroughbred mares and their foals.

The research investigates the concentrations of melatonin in the blood plasma of Thoroughbred mares and their newborn foals in the early post-partum period. The study finds that melatonin concentration, which is known to play a crucial role in birth preparation and offspring survival, is significantly lower in newborn foals than in their mothers and that this concentration declines differently between the two by the end of twelve hours.

Research Methodology

• The researchers involved 53 mare-foal pairs in the study and extracted blood samples from their jugular vein within twelve hours after birth.
• They measured the plasma melatonin levels in these samples using a method known as ELISA (Enzyme-Linked Immunosorbent Assay), a plate-based assay technique designed for detecting and quantifying substances such as peptides, proteins, antibodies, and hormones.
• They then adjusted the concentration of melatonin for the moment of parturition using a statistical tool called generalized linear model.

Key Findings

• They found the melatonin concentration to be 34.58 pg mL-1 in mares, while in newborn foals, it was significantly lower at 27.63 pg mL-1. This suggests that the production of melatonin might be elevated in the mares in preparation for birth.
• Interestingly, they observed that the melatonin concentration declined differently by the end of the twelve hours – it decreased less in the offspring than in the mothers.
• Additionally, when the mare was given artificial light supplementation at the end of gestation, the melatonin concentration in both the mares and their foals decreased by about 10 pg mL-1.

Implications and Future Directions

• This study indicates that the lower melatonin concentration in newborn foals might have an impact on the foal’s health and subsequent performance. Also, melatonin production may peak at the moment of foaling regardless of its actual timing, which plays a crucial role in ensuring the chances of survival of offspring.
• Given these findings, the researchers stress the need for further studies to monitor the melatonin concentration in the offspring.