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OSU Extension

College of Food, Agricultural, and Environmental Sciences

August 14, 2018 - 8:00am -- Anonymous

Corn silage harvest is a critical time of year for dairy producers.  Within the space of a few days to a couple of weeks at most, a year’s worth of feed is chopped, hauled and stored.  Decisions made or not made, during that timeframe affect the quality of silage fed throughout the year.  Taking some time now to think, plan, organize and prepare before the start of corn silage harvest can help to insure a better quality silage feedstuff.  Key decisions involve harvest timing as determined by plant dry matter content, monitoring kernel processing, use of a silage inoculant, matching silage delivery rate with packing tractors (bunker silos), and covering/sealing the silo.

The most important decision is harvest timing and that is dependent upon the plant moisture or dry matter (DM) content.   This determines the ceiling for silage quality.  If you don’t get this right, silage quality suffers and no other step in the silage production process can recover that lost potential.  Take time to get out in the field, collect samples to determine moisture content and continue to monitor plant moisture until harvest begins.  Collect at least five plants from random field locations, chop uniformly (approximately one inch pieces), and then determine moisture content using a Koster tester or microwave oven.  On average, plants will dry down 0.5% units each day after dent stage, although this can vary depending upon the hybrid and weather conditions.  There are some businesses in the area that will provide silage moisture testing and I can provide a list to anyone who is interested.

The goal is 30 to 35% DM (65 to 70% moisture) for bunker silos, 30 to 40% DM (60-70% moisture) for silo bags and 35 to 40% DM (60 to 65% moisture) for upright concrete silos. It is better to err on the side of chopping early and harvesting slightly wet silage rather than harvesting too dry.  Silage that is too dry undergoes limited fermentation and results in a less stable silage product.  If you are using a custom harvester, make sure you are communicating with that person and providing as much lead-time as possible to schedule your harvest.

Kernel processing can improve starch digestibility/availability.  Make sure the chopper knives and roller mill are in good condition and properly adjusted.  Replace worn shear bars and nicked knives.  The gap setting between rollers should be 1 to 2 millimeters (mm) (hint, a dime is 1.2 mm).  There are labs that will do a corn silage processing score (CSPS), which is useful for monitoring animal performance and providing a post-harvest assessment of the silage kernel processing, but the dairy manager should have some way of monitoring kernel processing during harvest so adjustments can be made on the spot as necessary.  One quick monitoring procedure involves filling a 32-ounce cup with fresh chopped corn silage.  Empty the cup onto a flat surface and count the number of whole and half kernels.  The goal is less than two whole or half kernels.  If more than that, make adjustments.

Have you purchased your silage inoculant?  There are two main types of silage inoculants; lactic acid bacteria (LAB) and bacteria that produce acetic and propionic acid, bacteria species L. buchneri.  Which to use?  LAB inoculant promotes better silage fermentation and L. buchneri helps to reduce spoilage and feedout losses.  L. buchneri is also helpful if silage feedout rate is less than 6 inches per day off the face and/or silage is fed during summer months. 

Do you have adequate packing capacity lined up?  The goal is to achieve a minimum silage density 40-45 lbs. of fresh forage/ ft3, which should provide a density of 15 lbs. of DM/ft3 or higher.  Higher packing densities result in less DM loss. The guideline for packing is to provide 800 pounds of packing weight for each ton of silage delivered to the silo or pack.  For example, if the harvest rate is 100 tons/hr. then the packing weight needed is 100 x 800 = 80,000 lbs. or 40 tons.  Each packing layer should be no more than 6 inches in thickness.  You cannot overdo packing. 

Cover the silo or pile as soon as the final packing is completed.  Covering prevents oxygen, weather and animals from getting into the silage pack, reducing DM and spoilage losses.  The recommendation is to cover with plastic of 6 to 8 mil thickness provide adequate overlap and weigh that plastic down, sealing the edges as well.  University research trials have demonstrated that the oxygen barrier 2-step products have reduced losses more than covering with the 6 to 8 mil plastic alone.

Finally, have a plan or system in place to manage and/or collect seepage from silage.  This leachate must not enter any waterway, or public body of water.  For more information about silage management, contact the Wayne County Extension office at 330-264-8722.