
WHY MAKE STINK SILAGE
On so many farms the familiar smell of silage is the sickly cloying smell of butyric acid.
The same smell that gets you ordered to take a shower when you come in for breakfast after feeding out, the smell that makes most townies hold their noses. That smell has become so familiar over the years that many farmers naturally associate it to silage – it is prevalent across most farms during periods when silage is being fed. The funny thing is, good silage shouldn’t really have any smell at all. The familiar sickly smell is actually a sign of secondary fermentation that has caused butyric acid to form within the silage. And that smell is costing you money as it is a sign that the silage has lost some of its nutritional value. A good quality fermentation should be purely based on lactic acid, and lactic acid actually has very little smell.
WHAT’S GOING ON IN THE SILAGE?
As mentioned butyric acid is formed during secondary fermentation, produced by aerobic clostridial bacteria this fermentation is indicative of decomposition of the naturally formed (anaerobic) lactic acid. Aerobic fermentation degrades much of the original protein in the grass. Some farmers are naturally confused because butyric acid fermented silage is so common here in New Zealand they inherently associate the butyric acid smell to silage.
Added to this dilemma butyric acid fermented silage, while still being nutritionally degraded, can be very stable. Its high acidity levels can make it largely immune to moulds and any further degradation. However at this point the cost has already been paid, this butyric acid fermented silage has lost much of its protein as this has been used up during fermentation.
GOOD SILAGE MAKING IS A FINE ART.