The role of penile stimulation and ejaculatory experience on the development and maintenance of reproductive behavior in the bull (Bos taurus).

To determine the role of afferent input from the penis and copulatory experience on the ontogeny of reproductive behavior, 49 bulls were randomly assigned to the following groups: control; surgical penile deflection (penis deviation), which prevents intromission; penile neurectomy; or penis deviation plus neurectomy. Sexual performance tests were conducted at 3-month intervals from 9 to 24 months of age. Bulls deviated but not neurectomized mounted more frequently than bulls in the other groups. The low mount frequency for control bulls in tests in which copulation occurred was due to the sexually quiescent postejaculatory refractory period. Preventing control bulls from copulating by affixing cloth patches to females' perinea increased mount frequency to the level of deviated bulls. It is concluded that copulatory experience is not essential to the development and maintenance of normal mounting activity. However, sensory stimulation from the penis facilitates the expression of sexual behaviors.