Sexual stimulation in male sheep and goats

Abstract

Previous research has shown that the sexual performance of male goats is enhanced by viewing the mating activities of other males prior to being placed with sexually receptive females. This same experience has no effect on the sexual performance of male sheep. In the present experiment, 14 male goats and 17 rams were individually allowed to sniff and nuzzle the anogenital region of an estrous female and engage in premating behaviors, but not mount for 20 min immediately prior to the administration of 30-min sexual performance tests. A female-absent control treatment was administered to these same animals prior to sexual performance tests. In the sexual stimulation treatments, male goats were more sexually active than rams ( P<0.001 for all variables). However, sexual stimulation did not affect the subsequent sexual performance of either species ( P>0.20 for all variables). Male goats and sheep did not differ ( P>0.05) in number of completed matings (services) but male goats exhibited more mounts without ejaculation ( P<0.001) and more mounts per service ( P<0.001) than rams. These results are discussed in terms of the reproductive advantage of sexual stimulation to male ungulates in the context of male–male competition vs. the absence of male competitors.