Preserving your fields for feeding: silage fermentation | Midwest Messenger

If you earned $100 after a hard day’s work, would you take that money home, place it in a safe, then remove it in a month and light it on fire?

Albeit an extreme example, this is essentially what producers do by cutting and storing silage without promoting proper fermentation.

Loss of nutrients from poor preservation not only impacts your feed inventory as dry matter decays, but also cattle performance as improperly fermented forage can harm the rumen of cattle. This hurts your economic bottom line twofold.

Regardless of whether you are ensiling corn, alfalfa or small grains, the basic process is the same. If ensiled and stored correctly, silage can maintain its quality for years.

Fermentation lowers the pH of the forage enough to hinder the growth of bacteria that would feed on the natural sugar and carbohydrates in the feed. If the moisture or sugar content of the silage is not balanced or the pile is exposed to oxygen, a substantial dry matter loss may occur, as explained by John Goeser, PhD, director of nutritional research and innovation at Rock River Laboratory and adjunct assistant professor at the University of Wisconsin-Madison. Goeser was one of six speakers at the Silage for Beef Conference held at the Eastern Nebraska Research, Extension and Education Center March 17.

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Under the wrong conditions, silage may take longer to ferment or may never stabilize, thus deteriorating. The wrong type of fermentation reduces total digestible nutrients (TDN).

“Tons that we lose are not representative of tonnage,” Goeser said. “If we lose 10% of our protein and 10% of our sugar, we are looking at $48 per acre that we left out there. This is corn grain and DDG or protein that we are going to have to bring back in the diet that could have been provided by the forage.”

How you manage the forage during ensiling and storage determines the silage quality when feeding. To properly ferment silage, follow these guidelines:

Prepare your storage area prior to chopping season. Silos can be bunkers, dug in the ground, drive over piles or bagged. For all storage methods, limit oxygen by covering and sealing the edges.

“Oxygen is our enemy,” Goeser said. “Yeast and mold thrive on oxygen.”

Packing and covering silage creates the anaerobic environment necessary for proper fermentation and extended storage.

To figure a target harvest date, determine your feeding goal. University of Nebraska-Lincoln beef systems specialist Dr. Mary Drewnoski explained how the differences in plant maturity affect yield and quality.

“You want your high yield and high quality—you want your cake and you want to eat it, too. It doesn’t work that way,” Drewnoski said.

Small grains harvested in the boot stage (grain head is enclosed in the sheaf) produce lower yields with higher crude protein (CP), whereas those harvested later in the soft dough stage (grain heads have a dough texture when squeezed) provide greater yields with lower CP but higher energy.

Proper fermentation relies on the sugar content of the forage, which directly correlates to the stages of plant maturity. Drewnoski warned that small grains transition through their stages very quickly.

“You do not gain crude protein by waiting to harvest,” Drewnoski said. “For higher quality forage, harvest at pollination to increase yield without sacrificing quality.”

She added that a distiller shortage would be an example of when to harvest forage early to gain higher CP content.

In addition to plant maturity, moisture affects the quality of silage. This includes a myriad of factors, such as plant maturity, weather conditions and windrowing practices.

“Avoid seepage loss by waiting for correct moisture before silaging,” said Becky Arnold of Lallemand Animal Nutrition, a global company with headquarters in Wisconsin that specializes in microbial fermentation.

Cutting forage at the correct height can also affect moisture content. Air flow to the windrows increases when the crop can lay on stubble and aerate. Moreover, cutting forage too close to the ground can result in contamination which “inhibits fermentation and dilutes energy value,” Arnold said.

Wide and shallow windrows create ideal drying conditions. Narrow and thick windrows typically result in wet pockets on the inside of the row, preventing uniform drying.

Allowing for wilting time between cutting and chopping can regulate moisture for fermentation, as well.

Each presenter at the Silage for Beef Conference stressed the importance of packing to reduce oxygen in the silage pile.

“Packing begins with the first load,” Arnold said.

As layer thickness increases, density decreases. Spreading the first load of silage and each subsequent load in layers 4 to 6 inches deep the entire way is ideal.

Other factors influencing packing density include length and slope of the fill ramp, tractor operator skill, tire width and pressure, tractor speed, slope or angle, load drops and turns.

Particle size also affects compaction because particles that are too long cause loose packing density. Arnold suggests designing someone to continuously monitor chop length during the silage making process for consistent results.

Applying inoculants to the silage can speed the fermentation process. A variety of options are available, including wet or dry products, homolactic acid bacteria or heterolactic acid bacteria and mixtures of the two. Desired speed or stability of fermentation, moisture content of forage and other factors influence which product should be applied.

Homolactic bacteria is efficient with the most economic end product, according to Dr. Limin Kung, professor at the University of Delaware.

Location of inoculation depends on the type. Liquid forms should be applied on the chopper, said Kung. For inoculants that are spread on the pile, distribute them evenly across the entire silage layer.

Do not use freshly treated water with peroxide or water with more than 0.5 to 1 ppm chlorine, which may kill the bacteria in the inoculant.

After being prepared, liquid inoculants are viable for a maximum of 36 to 48 hours (less if the water is above 95 degrees or the tank is dirty) and 24 to 48 hours for dry formulations, said Kung.

Water temperature affects viability of inoculants. Kung said that water must be less than 95 degrees Fahrenheit but not freezing. Because bacteria is fragile, avoid a freeze and thaw repetition when storing inoculants.

While inoculants can increase the speed or stability of fermentation, they do not fix problems associated with poor moisture or the presence of oxygen.

“Silage quality at feed out results from the quality you start with at harvest,” Kung said. He added that silage additives will not save bad management during ensiling, storage or feeding.

Maintaining the stable, anaerobic environment achieved through proper harvesting and packing will ensure that nutrients are preserved. Keep out moisture and oxygen by covering the pile or pit, then seal the edges.

Temperature indicates the success of fermentation. A properly ensiled product will raise 10 degrees Fahrenheit then cool, said Goeser. If more heat is produced or the silage does not cool, that is a sign of poor fermentation and a deterioration of TDN.

Silage may be a necessary food source this year as producers seek reliable and economical feed sources for livestock. Know how to manage silage from field to harvest to storage so you are not wasting time or money.

Reporter Kristen Sindelar has loved agriculture her entire life, coming from a diversified farm with three generations working side-by-side in northeastern Nebraska. Reach her at


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