Male-male competition fails to sexually stimulate domestic rams

Male domestic sheep are non-territorial and mate in multiple-male mating gr oups in which males compete for access to females. The following study test s whether rams are sexually stimulated by participation in or observation o f male-male competition for estrous ewes and if so, whether the response is affected by the sexual performance level of rams. Twenty-eight sexually-ex perienced yearling rains were given individual 30 min sexual performance te sts immediately after 15 min of (1) direct competition (DC) with other rams for 10 estrous owes whose perinea had been covered to prevent intromission s, (2) observing rams competing for estrous females (OC), (3) observing oth er rams without females (OR) and (4) observing an empty pen (EP). The DC an d OC treatments did not enhance sexual performance relative to the control treatments. Instead, the DC treatment resulted in a reduced rate of ejacula tion, possibly because of the physical exertion of repeatedly mounting fema les and accompanying male-male agonistic interactions. In addition, some ra ms may have become sexually inhibited because of the inability to attain in tromissions in the DC treatment. High- and low-performing rams did not diff er in their response to the four treatments. Frequencies of mounts without ejaculation and mounts per ejaculation were not influenced by treatment or sexual performance level. It was concluded that observing rams engaged in c ompetition for estrous females does not improve sexual performance and that sexual performance is reduced following direct competition for females. (C ) 2001 Elsevier Science B.V. All rights reserved.