Ovarian changes during early pregnancy in pony mares in relation to PMSG production.

This research studied changes in the ovaries of twenty pregnant pony mares over the first four months of pregnancy, and its correlation with PMSG (Pregnant Mare’s Serum Gonadotropin) production. Researchers observed a significant seasonal effect on ovarian size, follicles and ovulation rate, but not PMSG production, suggesting that pituitary gonadotropins primarily stimulate the ovaries.

Objective of the Research

• The main purpose of this research was to investigate the morphological changes in the ovaries of pony mares during early pregnancy, specifically assessing the size of the ovaries and the content of the ovarian follicles.
• Moreover, the study aimed to understand the relation between these changes and the production of Pregnant Mare’s Serum Gonadotropin (PMSG).

Methodology

• Twenty pregnant mares were examined daily, per rectum, over the first four months of their gestation.
• The research team made note of the estimated ovary size and follicular content of these mares.
• Blood samples were collected from sixteen mares out of the total and these were tested for their PMSG content. This was done to study the relationship between PMSG levels and ovarian changes during pregnancy.

Findings

• The researchers found a prominent seasonal effect on the ovary size, follicular content, and ovulation rate during the first four months of pregnancy in the mares.
• However, no such seasonal effect was observed on PMSG production.
• Thus, through this study, it was deduced that PMSG production does not fluctuate with the changing seasons, unlike the mare’s ovary size, follicular content, and ovulation rate.

Conclusion

• From the above findings, it was concluded that PMSG production is synergistic, or works in conjunction with, gonadotropins originating from the pituitary gland.
• These pituitary gonadotropins were hypothesized to be the primary stimulus on the ovary of the pregnant mare.
• This suggests that these hormones play a critical role in regulating the changes in the ovary during early pregnancy, and the seasonal factors that influence these changes do not have a significant influence on the production of PMSG.