Oral and injectable synthetic progestagens effectively manipulate the estrous cycle in the Przewalski’s horse (Equus ferus przewalskii).

This research study explores effective ways to manage the reproductive cycles of Przewalski’s horses, an endangered species, using oral and injectable synthetic progestagens, specifically altrenogest and PGF2α. The results indicate that these substances can successfully alter the horses’ estrous cycles.

Study Design

• The aim of the study was to evaluate the use of altrenogest and PGF2α, delivered orally and via injection, to modulate ovarian activity in Przewalski’s mares.
• The scientists monitored the mares’ reproductive cycles via urinary steroid hormone changes and rectal ultrasound scans to observe follicular changes.

Experiment Methods

• In the first study, five mares underwent a 14 day treatment course with oral altrenogest, observed over 11 cycles.
• In the second study, mares were treated for 12 days with oral altrenogest (5 mares followed over 5 cycles) or with a single injection of biorelease altrenogest (6 mares followed over 10 cycles).
• All groups received a dose of PGF2α two days before the end of the progestagen treatment.

Results and Interpretation

• The first study found positive responses in 54% of the observational cycles, signified by normal ovarian follicular development after the hormone treatment.
• The second study showed positive responses in 80% of the observational cycles for both oral and injectable altrenogest formats, as demonstrated by the formation of an ovulatory follicle.
• The findings suggest suppressive impacts on urinary estrogens and progestagens due to the use of injectable altrenogest.
• The outcomes indicate that the estrous cycles of Przewalski’s mares can be effectively manipulated using a 12-day oral or one-time injectable course of altrenogest alongside PGF2α.

Applications for Conservation

• The results may have significant future implications for the conservation of this endangered species.
• Successfully manipulating the estrous cycles could pave the way for establishing a routine for timed artificial insemination, a key method for the genetic management of endangered species.