Oestrus, ovulation and plasma hormones after prostaglandin F2alpha in mares.

The research looked at the luteolytic impact of Prostaglandin F2alpha (PGF2alpha), a hormone for reproduction, in mares. Administered during early dioestrus phase, it resulted in lowered plasma progesterone levels, induced oestrus and ovulation, although the oestrus duration was longer than that of a natural cycle while the ovulation timing remained the same.

Study Principles

• The study’s main objective focused on the impact of Prostaglandin F2alpha (PGF2alpha) on the ovulation and oestrus pattern in mares. PGA2alpha is a hormone linked to reproductive cycles in mammals, particularly its role in initiating uterine contractions.
• The PGF2alpha was administered during the early dioestrus phase of the mare’s cycle, a period following ovulation where the corpus luteum (an empty follicle turned endocrine structure) forms to produce progesterone.

Methodology and Results

• PGA2alpha was infused or injected into mares of mixed breeds on the 7th to 9th days following ovulation. The result was a significant drop in their plasma progesterone levels which subsequently led to induced oestrus (the reproductive phase when the female is receptive to mating) and ovulation (the release of eggs from the ovary).
• The study noted that upon this infusion of PGF2alpha, the length of the oestrus phase was significantly longer compared to a natural cycle. Nonetheless, the timing of ovulation with reference to the end of oestrus remained unchanged.
• The researchers found that the return time to oestrus after luteolysis (the process of corpus luteum degradation) did not depend on the amount of PFG2alpha given within the tested range. From their study, they were able to induce luteolysis as early as Day 5 after natural ovulation.

Conclusions and Significance

• The researchers present persuasive evidence that manipulating the hormone PFG2alpha can alter the reproductive cycle in mares. The ability to control ovulation and oestrus intervals could potentially have significant implications for breeding programs.
• Despite longer oestrus periods, the timing related to ovulation does not change, underscoring the luteolytic role of PFG2alpha and its influence on the physiological processes within the mare’s reproductive cycle.