With fall weather here, frost warnings are on the way. Producers often question the investment value of inoculating frosted forage that has been lying in a swath or windrow for several days.

To determine the best course of action, assess the degree of damage to the crop. If you don’t see mold, ensiling is an option. However, if you see mold, ensiling may not be an option.

When you are bailing as dry hay or disposal, there are two reasons to have a highly researched inoculant product on frosted forages:

1. Strains can quickly dominate fermentation over undesirable epiphytic (background) microbial populations that come in with the crop.

2. Inoculants provide more efficient utilization of fermentation sugars on the crop.

The ensiling process involves a bacterial population and a substrate source in the form of soluble sugars to produce sufficient concentrations of silage acids in an effort to reach a desirable terminal pH. 

Laying hay in swaths or windrows for several days under certain conditions, such as rain, can cause leeching of the crop’s sugars.

According to Pioneer’s technical service sample database, the average soluble sugar concentration of pre-ensiled alfalfa is 10 percent. Rainy weather, for example, will result in forages entering the silo with sugar levels at some concentration less than 10 percent.

Frosting over an extended period could have a similar effect.

The bacterial population that comes with the crop, known as epiphytes, generally increases with frosted forages. This doesn’t mean the increased epiphytic colony-forming units (cfu) will make the crop ferment faster.

In fact, many of the additional soilborne bacteria are inefficient at helping with fermentation and generate excessive heat during the ensiling process.

Highly researched bacteria in inoculants better utilize the remaining sugars in frosted forages, ensuring efficient fermentation. Relying on epiphytic populations that came with the crop can be inefficient and may exhaust the plant sugars before achieving a desirable terminal pH level.

Silage fermentation is a highly complex process dependent on many variables that are exacerbated by stresses such as frost. Epiphytes coming in with the crop are constantly changing, and inoculation minimizes the variability of this factor.

Pioneer’s forage additive researchers select inoculants to work across a wide variety of conditions, and even outside of this range, these inoculants are better than gambling on nature.

One of the research criteria for choosing the strain combinations in inoculant products is their ability to dominate quickly over the epiphytic population coming in with the crop, resulting in highly efficient fermentation.  FG

Matt Laubach
Dairy Specialist
Pioneer