February 28, 2014
Female Goats Go GaGa Over Males’ Hairy Head Stench
[ Watch the Video: What's That Smell? Lady Goats Love It At Least ]
Lawrence LeBlond for redOrbit.com - Your Universe Online
This seemingly unpleasant stench may not get our juices flowing, but to female goats, it is enough to put their brain into overdrive and trigger their reproductive systems.
This study, led by Ken Murata and Yuji Mori at the University of Tokyo, is the first to uncover a specific pheromone that activates the central reproductive axis in female goats. And although this study was conducted solely on goats, the researchers say the findings may be translatable to other livestock as well. They even go as far as to say it may even work in humans, due to the fact that the action and structure of the brain’s reproductive center is highly conserved in mammals.
Researchers had previously determined that it is the hair of male goats, not the urine, which drives their pheromone activity. While it was discovered that organic solvent extracts of the male’s hair retain the pheromone activity, a specific primer pheromone remained unidentified. Primer pheromones elicit long-term physiological events required for ovulation and reproduction, as opposed to releaser pheromones, which induce immediate sexual behaviors.
For their study, the team decided to focus their attention on components of the male essence, along with the largely unexplored neutral fraction. They found that the male goat’s pheromone is synthesized in the head skin. With this knowledge, they collected the scent from the goat using a custom-made head cap. After a week of collecting samples from both normal and castrated male goats, the team analyzed what they had.
Of the chemicals produced by both sets of goats, the team found several that were specific to the intact males only, including 4-ethyloctanal, which has the power to activate the gonadotropin-releasing hormone (GnRH) pulse generator in the female goat’s brain, which in turn governs the reproductive endocrine system.
Using a method they developed in the lab -- real-time electrophysiological monitoring -- the team was able to show the effects of the chemical on a key region of the goat’s brains.
"In 4-ethyloctanal, we identified a novel chemical that had never been demonstrated in nature before. This was our first surprise," Yukari Takeuchi, a coauthor of the paper from University of Tokyo, said in a statement.
Also, the 4-ethyloctanal oxidizes to 4-ethyloctanoic acid, which is a main ingredient of the “goaty odor” that has been known for decades to attract the ladies to their counterparts.
"We are tempted to speculate that this is a clever reproductive strategy of the male goat to alter behavior and activity of the reproduction center in the female for mating by a single molecule," Takeuchi said.
Commenting on the study, Peter Brennan from the University of Bristol finds the discovery of importance.
“There are relatively few instances in mammals where an individual compound has been positively identified as having a pheromonal effect,” he says. “There are fewer still in non-rodent species that have commercial importance,” he told Ed Yong of National Geographic.
With more work, farmers may be able to use this chemical to more precisely control the reproduction of their herds. Murata and his team are also now looking to find a similar pheromone in the cow, which would be of even more importance.
“I would expect that what they find in the goat will be true for other mammals and can be more easily studied in more traditional scientific models such as the mouse,” Lisa Stowers, of the Scripps Research Institute, told NatGeo.
While Murata’s team thinks their findings could translate to humans, Stowers doesn’t see it happening.
“This finding is unlikely to translate to human reproduction,” since we don’t seem to have any pheromone-detecting neurons similar to the ones that Murata studied in his goats, she said.
She also noted that the team did not show how the pheromone actually affects the GnRH neurons or how a brief sniff can lead to long-lasting changes over several days.
Takeuchi agreed, noting the team is currently building a device that would release the pheromone continually so they can study how the female’s reproductive behavior changes in the absence of actual males.