The following is a summary submitted with the application. It will be updated when the student’s abstract/thesis is received.
Multiple studies have demonstrated that male animals adjust the quality and quantity of sperm released in an ejaculate when they perceive that their sperm may face competition in the race to fertilise eggs.
For example, a study in 2005 (Kilgallon and Simmons 2005) found that when men viewed image content of another male and a female prior to ejaculation, sperm quality was significantly better than when men viewed images of just women alone. Additional studies since 2005 confirm this, suggesting that sperm competition affects sperm motility and viability, both highly important traits of sperm for reproductive success, and that responses competition cues are almost instantaneous (Simmons and Fitzpatrick 2012).
The proposed study will test whether males similarly respond to an olfactory cue of sperm competition, with the aim of developing a simple method of increasing sperm quality and quantity when collecting ejaculates for use in ART. Wool from ‘competitor’ rams will be collected during the breeding season, and attached to the backs of ewes during collections. The quantity and quality of sperm in ejaculates will be compared to controls collected in the absence of ‘competitor’ wool. Pheromones and olfactory cues in wool are enough to induce the ‘male effect’ in sheep and goats, inducing ovulation in isolated ewes. Hence it is hypothesised that this olfactory cue will also induce competitive responses in rams.
It is hypothesised that exposure to an olfactory cue of sperm competition will allow for collection of a higher quality and larger quantity ejaculate. Larger quantities being collected in one collection allows for maximised production of ejaculate for producers, and higher quality ejaculates are likely to improve the success rates of ARTs. Hence, this project may increase the efficiency and success of ART breeding programs in the wool industry.
References:
Kilgallon, S. J., Simmons, L. W., 2005, “Image content influences men’s semen quality”, Biology Letters, vol. 1, pp. 253-255
Simmons, L. W., Fitzpatrick, J. L., 2012, “Sperm wars and the evolution of male fertility”, Reproduction, vol.144, pp. 519-534