Induction of male sex behavior in pony mares with testosterone propionate.

The research is about an experiment where two pony mares were given testosterone propionate injections to induce male sex behavior. The study found that the treated mares then exhibited male-like behaviors such as mounting, biting, and vocalizing, particularly toward estrous mares, showing that testosterone can induce male sex behavior in mares.

Methodology

• The researchers selected two pony mares and administered them 150 mg of testosterone propionate every other day for 20 days, amounting to ten injections. After the initial 20 days, the injections were given every ten days.
• For the purpose of comparison, two other mares and a stallion were not given any treatments and thus, served as the control group.
• The testosterone propionate was dissolved in absolute ethanol and injected subcutaneously.
• To assess the effects of the testosterone, sex behavior tests were conducted 26 and 40 days after the first injection.

Results

• The results revealed a noteworthy difference in the behaviors of the testosterone-treated mares and the control group.
• The control mares exhibited very limited male sex behavior. However, the testosterone propionate-treated mares displayed male behaviors such as mounting, biting, vocalization, sniffing, and the flehmen response in the presence of an estrous mare.
• Despite displaying male behaviors, the testosterone propionate-treated mares did not exhibit behaviors such as sniffing, flehmen, and vocalizing to the same extent as the stallion when introduced to an estrous mare. However, they were more active in mounting and biting the estrous mares compared to the stallion.
• The researchers found that the testosterone propionate-treated mares and the stallion took 23.3 +/- 9.7 seconds and 172.5 +/- 22.5 seconds respectively to mount an estrous mare after being introduced into the pen.
• In a ten minute test, the average numbers of times that the estrous mares were mounted by testosterone propionate-treated mares and the stallion were 4.0 +/- 1.3 and 1.0 +/- 0 times respectively.
• The testosterone propionate did not induce the treated mares to mount non-estrous mares.

Conclusion

• Based on these observations, the researchers concluded that testosterone propionate can induce male sex behavior in intact mares. Moreover, the treated mares effectively detected and responded to the state of estrus in other mares.