Clostridial Fermentation...Not Good

By John Hibma

Photo by Ladyheart/

It was a bitterly cold morning, the beginning of January, as I was minding my own business traveling north on Route 87 in Connecticut, having just visited with a customer. I was listening to someone on the radio pontificating about the fiscal cliff that our country had just gone over and how it was going to affect my way of life when I looked in the rearview mirror to see the flashing red and blue lights of a Connecticut state trooper.

He got me with a laser going 54 in a 35. The fine was going to be $180, and of course I did what any good, law-abiding citizen would do ... I entered a plea of "not guilty" and sent the ticket back to the court. My first court appearance was in early April, where I learned what my options were: I could pay a reduced fine and the infraction would still go on my record, meaning higher insurance premiums; I could go to court and argue my case (what case?) in front of the judge; or I could volunteer for 18 hours of community service at an approved nonprofit service organization, which would result in the removal of the fine and violation from my driving record. By the way, this was my first traffic citation in over 10 years, and I drive between 30,000 and 40,000 miles per year.

Basically, I had to make the best out of a bad situation, so I spent my 18 hours volunteering at a local food bank to keep my driving record clean.

That's sort of what a dairy farmer has to do with a bad pile of haylage or wrapped baleage: make the best out of a bad situation. You know, that stuff you chop in the spring and summer between rainstorms that never has a chance to dry down, and you pack it in the bunk or wrap it, and it turns into this vile-smelling stuff that you can't stand to get near, and you have little choice but to feed it to your cows.

Producing a good hay crop forage in the Northeast is a real challenge, especially when it's supposed to be fermented. If you're trying to make bales of dry hay, any amount of moisture will cause some heating while it's still in the windrow, and you'll end up with some heat-damaged protein, not to mention that dusty, tobacco-smelling condition. In a lot of ways, a barn full of discolored square bales is still way better than a bunker full of haylage that went through clostridial fermentation.

Clostridial fermentation occurs mainly due to the lack of water-soluble carbohydrates (WSC), which are necessary for lactic acid formation in a good pile of silage. Unlike corn, which is loaded with starch, hay crops have less WSC and starch. The WSC is necessary for lactic acid formation. Ideal fermentation for silages requires abundant lactic acid, which uses up oxygen and shuts down oxidation and heating. If the WSC is not there, clostridial fermentation will take over.

Clostridia spores come from the ground and can easily contaminate a hay crop through mud on tires or by mowing too close to the ground. Even a small amount of contaminated soil will inoculate a pile of haylage and spread throughout if moisture conditions are conducive.

The main challenge of ensiling grasses and legumes in rainy regions is getting the plant moisture to the correct level to prevent clostridial fermentation. Under normal conditions (no drought) your grass or legume forages will be around 20 percent dry matter (80 percent moisture) as they're standing in the fields. The desired goal for ensiling is to get dry matter up around 35 to 40 percent. So there must be some wilting and moisture removal while in the windrow prior to chopping and packing.

However, too much wilting time has been found to be the main culprit in causing clostridial fermentation. Immediately after the plant has been cut, cellular respiration begins to consume the WSC, which is the very fuel it needs for proper fermentation. So there is a very fine line between letting it wilt long enough to get the moisture down and dry matter up and too much wilting, which starts to destroy the necessary carbohydrates for fermentation.

Clostridia spores are more easily destroyed by lactic acid in a drier environment, meaning higher dry matter. If the crop remains too wet, lactic acid is less effective in destroying clostridia, and the result is less effective and unstable fermentation acids, the worst of which is butyric acid and other problematic nitrogen compounds. If hay crops go into a bunk or a bale wetter than 50 percent, you can expect a lot of this vile-smelling compound.

The presence of even small amounts of butyric acid in haylage should be cause for concern for dairy producers. Butyric acid (also called butyrate) will be converted to ketones once consumed by the cow and, when in high enough levels, will cause ketosis. Due to its vile smell, cows will often decrease feed intakes of haylages and TMRs that are heavily contaminated with butyrate. The presence of excessive butyrate in the rumen means there is less propionate being made in the rumen, which is necessary for glucose production (the cow's primary energy source), as well as less acetate being made (the primary acid necessary for butterfat synthesis).

With so much at stake with high feed costs these days, being stuck with haylage that is high in butyric acid is a bad situation to be in. Haylage with butyric acid levels over 1 percent will almost certainly diminish milk production and/or components. For the really bad stuff, I'd say don't feed it to any of your animals ... throw it all out. A silage inoculant with lactic acid-forming bacteria is an absolute must when making fermented hay crops. Because the potential for clostridial fermentation is so high, don't fret about the extra cost, just do it. It will keep you out of trouble and pay for itself in the long run.

The author is a dairy nutritional consultant and works for Central Connecticut Cooperative Farmers Association in Manchester, Conn.