Here are some things you may want to consider when making decisions regarding the harvest and storage of high moisture corn.
The type of silo for storing the high moisture corn must be considered first. Conventional (CON) and oxygen-limiting (OL) silos must be approached differently when specifying minimum, maximum and desirable moisture levels. Table 1 illustrates these relationships.
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High moisture shelled corn above 32% kernel moisture may result in difficulty in unloading from typical OL silos equipped to handle high moisture shelled corn.
For corn stored above 40% moisture, an undesirable fermentation will take place and yeast will predominate along with high ethanol levels. Animal acceptance may be poor with this type of fermentation.
Delaying harvest is still the best recommendation if the corn is too high in moisture. Recognize that winter is rapidly approaching and one must balance the risk of being unable to get the corn harvested against having a less than optimum product stored.
Recommendations for Harvest, Processing and Storage of Wet Corn
1. Check corn kernel moisture from different fields and harvest the one with moisture closest to optimum first. Corn with higher than desirable moisture tests may be less of a problem when fed out during the coldest months and therefore would be best to put on the top of the silo. The very wet corn may be prone to spoilage upon removal from the silo or even prior to removal if a good fermentation was not realized and the pH lowered from acid production.
2. Take care to only use minimum processing of the corn. It is very easy to get excessively fine high-moisture corn that may result in fat test depression, off-feed problems and increased incidence of displaced abomasums resulting from rumen acidosis. As the corn approaches optimum moisture content, increase the degree of processing.
3. Consider the application of a lactic acid bacterial inoculant to the very wet corn at a minimum of 100,000 colony forming units/gram of fresh corn to help insure a good fermentation. Ensiling the high moisture corn during cold weather and after several days of freezing temperatures may severely reduce the population of naturally occurring lactic acid-producing bacteria.
4. Consider the application of propionic acid at 12-15 lb/ton of actual propionic acid. There are a number of products with less than 100% propionic acid. Be sure to adjust application rates to insure application of the recommended rate of actual propionic acid. The application of propionic acid must be placed onto the grain. Applying the acid by spraying onto the corn as it arrives at the blower throat has often resulted in less than satisfactory results due to excessive loss of the acid through volatilizing the propionic acid. Placing the acid on the corn as it is augured to the blower is the preferred method of mixing the acid so that all corn is treated uniformly.
5. When significant mold is observed on the kernels and cob, it will be best to harvest and store as shelled corn. The optimum method to preserve this corn would be drying to storable moisture and screen off the fines. Where drying is not an option, propionic acid would be the recommended treatment for corn showing a significant proportion of moldy ears. The propionic acid will not lessen any problems from the mold, but will likely prevent the problems from getting worse.
6. Be careful to plan for ample removal rate from the silo of the resulting high moisture corn. A removal rate of 3 to 4 inches per day may be required to prevent heating during feeding on warmer weather. Treating the bottom third to half the silo of high moisture corn with propionic acid (12-15 lb/ton) may be desirable to insure quality during warm weather feeding.
7. If high moisture corn is stored in bags, locate bags away from trees, long grass and keep snow removed around them to allow predators access to rodents, squirrels, etc. For best results, remove bagged high moisture corn during cooler months. Removal rates may be insufficient to prevent spoilage in smaller herds during the summer. Also, any punctures, rips, or tears in the summer can cause rapid and expansive spoilage.