Induction of male sex behavior in ewes with silastic implants containing testosterone propionate

In the first of two experiments, ovariectomized ewes with silastic implants containing testosterone propionate had higher concentrations of plasma testosterone than ovariectomized ewes with silastic implants containing testosterone (4.0+/-.2 vs .8+/-.1 ng/ml). In the second experiment, one or two 10 cm silastic implants filled with testosterone propionate increased concentrations of plasma testosterone and induced male sex behavior in ovariectomized ewes similar to plasma testosterone levels and male sex behavior in rams. The interval from initiation of the treatment to the first behavior test in which mounting was consistently observed was 14.4+/-2.9 days and once mounting behavior was consistently induced, the testosterone treated ewes mounted estrous ewes an average of 10.7+/-1.3 times during a 10-minute test.