The cycle of oestrus, ovulation and plasma levels of hormones in the mare.

The research article examines the patterns and timings of hormone level changes in relation to the oestrus and ovulation cycles in mares.

Research Objective

• The main objective of this research was to investigate the patterns of sex steroid hormones and pituitary LH concentration during the oestrus cycle and day of ovulation in mares.
• To better understand these patterns, the researchers also compared the hormone secretion of mares with other domesticated animals.

Methodology

• Six mares were utilised for the study, wherein their oestrus cycle period and ovulation day were examined in detail.
• Concurrent assays were performed to measure plasma levels of sex steroids, including progesterone, oestradiol, and androstenedione, along with the pituitary LH concentration.

Results

• Progesterone levels peaked during the dioestrus phase of the oestrus cycle.
• Levels of oestradiol and androstenedione hormones reached their maximum two days prior to ovulation and began to decline on the day of ovulation itself.
• Among the hormones monitored, oestrone plasma remained relatively stable throughout the cycle, fluctuating only between 9 and 12 pg/ml.
• Plasma LH concentrations increased to their highest point close to the ovulation period and then decreased slowly until mid-dioestrus.

Comparison with Other Animals

• The observed pattern of hormone secretion in mares is also compared in this study with previously reported patterns in other domesticated animals, although the abstract does not detail these comparisons or indicate whether the mares’ cycles are similar or different from those in other species.
• Because of this comparison, this research could potentially lead to new understandings of reproductive health and patterns in a variety of animal species.