Synchronization of oestrus in mares with a prostaglandin analogue and HCG.

This research studied the effectiveness of using a prostaglandin analogue ‘Equimate’ and HCG to synchronize oestrus, or heat cycles, in thirty-three mares. The process showed positive results, with a high number of mares ovulating within 24 to 72 hours after the second HCG dose. Further, it was found that measuring plasma progesterone levels could successfully determine ovulation, making some regular clinical procedures redundant.

Research Overview

• The study aimed to determine the effectiveness of a prostaglandin analogue, ‘Equimate’, and Human Chorionic Gonadotropin (HCG) in synchronizing the oestrus cycle, or the reproductive cycle, in mares.
• The mares went through a 13-day observation period to measure initial plasma progesterone levels before the experiment began.
• Important to note is that synchronization of a mare’s oestrus cycle can increase reproductive efficiency and help in planning breeding routines with better accuracy.

Treatment Method

• The mares received two courses of treatment, with each course including an injection of Equimate and a later injection of HCG, eight days apart.
• The first treatment aimed at removing luteal tissue and inducing ovulation by withdrawing progesterone. Luteal tissue refers to the corpus luteum, an endocrine structure involved in the mare’s menstrual cycle and early stages of pregnancy.
• The second course focused on synchronizing the oestrus cycle and ovulation. This was done by triggering luteolysis, or the degradation of the corpus luteum, of the induced Corpus Luteum (CL) in all the mares.

Results and Significance

• The results showed that a significant portion of the treated mares were able to ovulate within 24 to 72 hours after the second HCG injection.
• If fertility remained un-affected, the study predicted a high success rate for double treatment.
• It was concluded that the levels of plasma progesterone could be relied upon to accurately determine ovulation. This could negate the need for typical clinical procedures usually employed to establish the onset of oestrus and follicle rupture.