Harvesting Lodged Immature Corn for Silage

Was your corn field severely damaged by summer storms? Harvesting lodged immature corn for silage may be a favorable option. Immature corn silage is a unique feed – while yield is certainly compromised because grain accounts for upwards of 50% of silage dry matter yield, the overall energy content may not be as poor as expected. The relatively high energy value is due to:  

1. Sugars retained in the stover portion that were not translocated into kernel starch
2. High stover fiber (NDF) digestibility in the immature plant  

It is very important to have immature corn silage analyzed for fiber digestibility (NDFD), sugar content and starch level.

Two characteristics of immature corn silage can predispose cows to subclinical rumen acidosis (digestive upset) issues:

1. Kernels will likely be more easily broken by chopper processors allowing for easier rumen microbial access
2. Kernels contain a starch/protein matrix that will undergo a faster rumen degradation 

Nutritionists must deal with two important issues:

1. How the nutrients are partitioned (stover sugars and more digestible fiber vs. reduced but more ruminally available kernel starch)
2. What feed sources nutritionists use to compliment this unique mix of sugars/starch/fiber in the ration

Starch deposition is the primary driver of corn silage drying down as it matures in the field. Most of the moisture will be contained in the stalk and, without advancing starch deposition, moistures at harvest will likely be in the 70%-plus range. This lack of kernel starch in immature corn silage is what results in high moisture levels which may require management of effluent (runoff) to prevent environmental contamination. Silage effluent has very high “biological oxygen demand” which can cause significant fish kills in contaminated streams. To prevent excess effluent, do not chop finer than 19mm and do not over-process the crop as the immature kernels will not need aggressive processing. 

Nitrates should not be a concern for several reasons. Plants are presumably healthy and metabolizing prior to lodging, and the fermentation process degrades nitrates by 50% making any nitrates left in the silage within acceptable limits to ruminants. The only time nitrates could be an issue is if beef cattle are allowed to graze the unfermented crop.

Fermentation (lowering pH) also should not be an issue because the plants are very high in sugar content.  However, stressed plants are typically high in yeast counts, and soil contamination in downed plants may also expose the plant material to spoilage organisms. If corn is left in the field long enough for fungal growth, there is potential for mycotoxin production.

The high sugar content, even after fermentation is complete, coupled with high yeast can initiate the cascade of events leading to silage heating. This can cause unstable silage in the storage structure and feed bunk. It is recommended that silage to be fed out in the warmer times of the year be inoculated with Pioneer^® brand 11C33 to conserve dry matter (given already compromised yields) and reduce heating/palatability issues. For silage fed out in the colder winter months, Pioneer^® brand 1174 would be the inoculant of choice.

Harvesting downed corn is always a challenge. In general, farmers should be prepared to slow down and be patient when harvesting. Slowing down the head so it doesn’t turn as fast may be necessary to allow the head time to cut the corn and not pull it out of the ground. The best equipment and practices for harvest can depend on the direction of the lodging:

• If the corn is lying parallel with the rows, then a row head will likely be the best option for chopping.
• If the corn is lying against the rows, then a large-drum Kemper head is the best option.
• Harvesting in a single direction often helps the corn feed into the head better. This may be parallel, across, or diagonal to the rows depending on the direction of the lodging.

Farmers with crop insurance should contact their agents to be informed of any issues with taking the crop as silage.