Lets get technical about manure…
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There are two types of people: Those who crinkle their nose at the smell of cattle manure and those who acknowledge it slightly, simply stating, “Smells like money.” Two very different reactions spurred by three main compounds that make up two-thirds of manure odors, says United States Department of Agriculture (USDA) and Agricultural Research Service (ARS) scientists.

Two of the compounds, isovaleric acid and butyric acid, are volatile fatty acids produced during manure decomposition, the third is 4-methulphnol, an aromic compound – the combination of the three can create a powerful punch.