Plasma prolactin concentrations and cyclic activity in pony mares during parturition and early lactation.

The research paper analyzes the relationship between plasma prolactin levels and cyclic activity in pony mares during late pregnancy, foaling, and early lactation, indicating prolactin levels rapidly increased in the last week of pregnancy and later reduced to basal levels after 1-2 months following childbirth.

Research Methodology

• The study was conducted on five pony mares. Their blood was collected during the period of late pregnancy, foaling, and the initial levels of lactation.
• Using an homologous assay specific for horse prolactin, the researchers measured the concentrations of plasma prolactin in the collected samples.
• All through the research, regular estimates of cyclic activity in the mares were made.

Findings

• The research found that the levels of plasma prolactin significantly increased in the last week of pregnancy.
• Although the prolactin concentrations were variable, they remained high during the period of early lactation.
• By 1-2 months post-partum, prolactin concentrations returned to their basal or normal levels.
• Post-partum estrus, or the period of sexual receptivity after giving birth, occurred roughly 7 days after parturition in all the mares.

Special Circumstances and Observations

• One mare, whose foal died shortly after birth, demonstrated a sharp decline in plasma prolactin levels following the death of the foal.
• The same mare experienced an early estrous period occurring just 4 days after parturition.
• The pattern of changes in the levels of prolactin observed in the mares were found to align with those reported for other mammalian species, which suggests a consistency across different mammalian species regarding prolactin level fluctuations during pregnancy and post-partum periods.