HMSC: Don’t forget the H (Jon Urness)

Posted on September 4, 2014 in Forage Foundations
By Jon Urness, Vita Plus national forage specialist
Dairy producers have successfully harvested, stored and fed high moisture corn for many years. By now, most have the routine down pat. But when things go wrong, it’s often the lack of high moisture that causes problems.  Naturally, too much moisture can be a challenge as well, but the material won’t pack without adequate moisture.  In turn, it becomes difficult to store and ferment, and ultimately unstable and prone to spoilage when fed.

Many of today’s hybrids dry down very quickly, causing the harvest window to be very narrow. Scheduling custom harvest in a timely manner can also be a challenge.  And let’s face it: fall is a seriously busy time of the year on a farm.

No moisture means no fermentation
Moisture is essential for fermentation to occur.  Think about why we dry corn to 15 percent moisture or less when it’s stored as dry corn.  At that moisture, the chance for yeasts to grow is greatly reduced and we certainly wouldn’t expect fermentation to occur in our dry bins.

So is it reasonable to expect fermentation to occur at 20 or even 25 percent moisture in a silo, bunker or bag?  Can we call that high moisture corn? Those numbers are definitely at the low end of the spectrum and success is often dependent on the degree of processing and the integrity of the storage unit. In a perfectly maintained oxygen-limiting unit with a bottom unloader, 20 to 25 percent moisture may be acceptable, but is still a little on the dry side.  The University of Wisconsin Extension Team Grains offers this guideline for targeting moisture content of high moisture corn:

Consider the type of silo first.  High moisture corn can be stored in conventional, oxygen-limiting, bunkers or bags.  Recommended moisture levels for these silo types are presented in Table 1.

Table 1. High moisture corn storage in conventional, bunker, bag and oxygen-limiting silos

Conventional top-unloading silos, bunkers and silo bags
Corn kernel moisture, %
Minimum Desired Maximum
Ear corn 26 32-36 40
Shelled corn 26 28-32 36
Bottom-unloading oxygen-limiting silos
Corn kernel moisture, %
Ear corn-rolled* 26 28-32 36
Shelled corn 24 26-28 32
*Oxygen-limiting silo with forage unloader

Snaplage offers special challenges
Snaplage brings a wide range of ratios between kernel, cob, husk and even stover.  That variability creates additional challenges. Adding cob, husk and stover reduces the density of stored material, making it difficult to achieve good density for fermentation and storage. These coarser materials cause greater porosity in the feed, so moisture and particle size become even more critical.

Moisture levels between 36 and 42 percent are optimal for snaplage.  To keep particle length low and starch accessibility high, chopper settings of 1/4- to 3/8-inch theoretical length of cut and processing roll gap of 1 to 2 mm are recommended. Additionally, processing roll speed differential should be geared to 20 percent or greater.  Click here for a Vita Plus technical bulletin titled “Opportunities, Risks and Challenges in Harvesting, Storage and Feeding of Snaplage.”

When aerobic stability is a concern
High moisture corn – whether it’s ground shell corn, ear corn or snaplage – is a high value, concentrated feed and very subject to aerobic stability challenges.  Minimum feedout rates from bunkers, bags and even top-unloading silos can be compromised.  Treatment with a preservative or inoculant to enhance aerobic stability can be helpful in such cases.

Propionic acid is very effective, but gets rather expensive when applied at the proper rates. For example, UW-Extension recommends applying 15 to 20 pounds of propionic acid per ton to corn that is 25 percent moisture and will be stored for 12 months. Crop-N-Rich Buchneri 40788 or Crop-N-Rich Stage 2 applied at 3 grams per ton has proven to be a very effective and economic strategy for improving aerobic stability.


Category: Feed quality and nutrition
Forage Foundations
Forage inoculants
Forage storage and management