Think of a ghastly smell. Skunk? Halitosis? BO? Outhouse? Rotting fish? Rancid butter? Dog flatus? Decomposing flesh? All devastating. But let鈥檚 not forget the penetrating fragrance of a billy goat. Especially a wet one. That will horrify any nose. Unless that billy goat, or "buck" in more scientific terms, happens to be castrated. Along with the loss of manhood comes the loss of smell. Actually 鈥渟mell鈥� doesn鈥檛 do the aroma justice. 鈥淩eek鈥� is a better description of the unforgettable stench. And if you handle one of these animals you will learn what 鈥渦nforgettable鈥� means. The piercing odour sticks to clothes and skin and is very tough to eliminate. You don鈥檛 want to be wearing clothes you are fond of when you have an encounter of the male goat kind. And gloves are definitely the order of the day.
Since 鈥渨ethers,鈥� as males that have been deprived of their testes are known, produce no smell, it stands to reason that the aroma of an intact male has a connection to reproduction. That has actually been demonstrated. When exposed to the scent of a male goat, females will ovulate and become receptive to the advances of the buck. Determining the exact composition of the scent that activates the female is of interest to researchers because it may lead to a way of ensuring that females are in rut for breeding. This could be a more economical and a less invasive way of stimulating ovulation than hormone treatments now used by some breeders. Obviously, the first step in such research is to collect a sample of the scent. Although the identity of the brave scientist who first carried out the pioneering research has been lost to the pages of history, it is known that the scent is wafted out from glands on the billy鈥檚 head.
So how do you collect the fragrant compounds? You design a helmet equipped with a material that absorbs volatiles, extract these with a solvent, and subject the solution to analysis by gas chromatography and mass spectrometry. A gas chromatograph separates the components of a mixture and a mass spectrometer can identify the individual compounds. And there are lots! Dozens! Determining which are responsible for stimulating ovulation in the female is a challenge, one that was cleverly met by a group of Japanese researchers. By implanting electrodes in a specific area of the brain of female goats they managed to measure electrical signals associated with the firing of nerve cells that are involved in the release of the hormones that stimulate ovulation. Starting with mixtures of compounds, and then narrowing these down to fewer and fewer components, they eventually managed to determine that 4-ethyloctanal produced the strongest response. It now joins the array of compounds recognized as 鈥減heromones,鈥� namely chemicalssecreted by animals that influences the behavior or physiology of others of the same species.聽Interestingly, 4-ethyloctanal has a rather pleasant citrus-like odour.
While this compound has not been found in nature before, it has long been familiar to perfumers and artificial flavour manufacturers. A patent back in 2002 was filed for the use of 4-ethyloctanal as a fragrance chemical to enhance the bouquet of perfumes, toilet waters, colognes and other personal products, as well as for its use as a food additive to boost flavour. If 4-ethyloctanal isn鈥檛 responsible for the torturous stench of male goats, what is? The chromatographic analysis reveals a number of compounds in the family of carboxylic acids. These are widespread in nature, the simplest ones being formic acid found in ant venom and acetic acid, a dilute solution of which we know as vinegar.
鈥淪imple鈥� in this case refers to the number of carbon atoms in the acid鈥檚 molecular structure, with putridity increasing with the number of carbons. Propionic acid, which has three carbons, elicits the sensation of body odour, which is not surprising since it is produced by bacteria on the skin. Butyric acid is responsible for the characteristic smell of human vomit. It is also found in goat scent. As disturbing as it is, it pales in comparison with the stabbing odour of the six-carbon, caproic acid, appropriately deriving its name from 鈥渃aper,鈥� the Latin for goat. Even if you have never been near a goat, you may have encountered its dramatically unpleasant odour if you have ever sniffed the demposing seeds of the ginkgo biloba tree. Two other acids, caprylic and capric, also derive their names from 鈥渃aper,鈥� for good reason. They also contribute to the fragrance of male goats. Staying away from randy old goats is a good idea. Unless they have been deprived of their privates.
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