Studies on mild composition and lactogenic hormones in the mare.

This research investigates hormone levels and composition of mammary secretions in Thoroughbred mares during late pregnancy, birth, and early lactation, highlighting a rise in lactose and triglyceride levels, while efforts to identify a placental lactogen presence or measure lactogen hormones in their plasma remained unsuccessful.

Study Objective and Methodology

• The research aimed to understand the composition and lactation capacity of mammary secretions in Thoroughbred mares, with a focus on lactose and triglyceride concentration levels.
• The study involved collection of mammary secretion samples from eight mares during three critical phases: the last week of pregnancy, at the time of foaling, and after one week of lactation.
• Specific assays, or investigative procedures, were used to identify and quantify both lactose and triglycerides in each sample, keeping track of their levels across time.

Findings and Conclusions

• Both lactose and triglycerides were found in all samples taken before birth, signifying that mares’ udders begin the lactation process well before parturition.
• The concentration of each substance rose progressively from late pregnancy to the foaling period, and then through the early lactation stage; milk samples collected between 7 and 9 days postpartum contained 6.0g lactose/100 ml and 1.8g triglycerides/100 ml.
• The researchers were unable to identify any presence of a placental lactogen, a hormone produced by the placenta that stimulates breast milk production in other mammals, or to measure the count of any lactogenic hormones in the mares’ plasma.

Implications of the Study

• The study provides valuable insights into the lactation process of Thoroughbred mares, including their mammary secretion composition and hormone activities throughout late pregnancy and early lactation.
• Knowing that secretory capacities are established before birth and lactose and triglyceride concentrations increase over time is crucial information for those involved in equine care and rearing.
• The inability to find placental lactogen or quantify lactogenic hormones suggests that the mare’s lactation mechanism may differ from other mammals and warrants further research.