Corn silage harvest may seem like a long way off, but preparation for a successful harvest begins now. Improper silage storage and fermentation can result in losses up to 20% prior to feeding. Plan your storage now to keep excessive storage losses from happening to you.
The enemy to good silage is oxygen. Quality silage needs anaerobic fermentation to occur to maintain quality and ensure stability over the storage period. While factors like moisture content at harvest and packing density are important to maintaining an oxygen free environment, the physical location and way silage is stored can play an equally impactful role.
When too much oxygen is present in the silage pile, respiration occurs, turning plant sugars into heat and carbon dioxide. This results in lower forage quality and overall yield, though it may not look like it at first glance. The burning off of sugars during respiration causes the left over plant structural components to condense. In the end, the visible layer of spoilage often seen on silage piles may represent 2-3 times that amount as layers shrink and condense.
Respiration also produces heat. This heat build-up causes three negative outcomes in silage piles. First, it limits the activity of lactic acid bacteria. These microbes prevent protein binding to plant lignin during fermentation, without which feed becomes less digestible by the animal. Second, heat encourages the growth of undesirable fermentation bacteria, yeasts, and molds, all of which lower forage quality and can reduce yield. Lastly, heat early on in the ensiling process can end up with browning caused by a Maillard reaction. While these browned bits may be highly palatable, they are a sign of denatured protein, once again lowering silage quality. Maillard browning produces even more heat during reaction, increasing the risk that temperatures rise to the point spontaneous combustion is possible.
Before we begin work on preventing oxygen in to our stored silage, we must first select a storage location. Bags and piles should be placed on elevated locations that allow snow and rain to drain away from the silage and feed out area. Special consideration should be taken for snow drift patterns to prevent restricted access during the winter. Equipment traffic for feeding out of a pile or bag will be high and the ground will take a beating, Sites with poor drainage can result in ruts and mud holes making feeding more difficult. Provide plenty of room around the silage for maneuvering of equipment during both harvest and feed out. Finally, keep the area around bags or piles away from trees, trash piles, and other possible shelters for small animals. Creatures like mice, squirrels and other small animals will gnaw holes in silage coverings, seeking food and shelter. By limiting possible shelters, keeping weeds and grass around silage trimmed up, and immediately repairing any holes noticed, wildlife damage can be kept to a minimum.
Once we’ve selected a location, how we plan to store our silage needs to be considered. Bagged silage is a versatile option that allows the storage location to move year to year. Additionally, silage is set right off the bat to be in an oxygen free environment, especially if we are vigilant in repairing wildlife damage. Silage piles are the more traditional approach and can allow for greater volumes of silage to be stored in a smaller area. Placing your pile on a cement pad or bunker is optimal for oxygen exclusion, but be sure to check these structures for cracks and repair any that are found annually to maintain their integrity. If silage is an annual feedstuff on your operation, the reduced loss a permanent structure provides can offset the cost when spread out over several years.
Even temporary piles can be made more oxygen free if planed for ahead. Line the sides of your bunker with bales and place an oxygen barrier plastic down on the sides and for several feet under the bottom to really seal the pile’s sides. At a bare minimum, placing plastic on top of the pile is an investment worth the time, labor, and money. By covering the pile we prevent oxygen from moving into the pile from the top and reduce precipitation exposure. Both rain and snow can penetrate the pile if uncovered, bringing more oxygen into the pile dissolved in the water itself, can throw off fermentation by upsetting the moisture balance leading to spoilage, and can result in the pile “weeping” and leaching out valuable energy and protein.
Corn silage is a valuable feed resource, but can suffer from high levels of loss when stored incorrectly. Whether choosing temporary option like bag or drive over pile or something more permanent like a concrete bunker, doing what you can to keep oxygen out of your silage requires planning now. Pick an appropriate location for harvest and feed out success and store correctly to minimize feed losses later on.
-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: ben.beckman@unl.edu