It’s well known that some loss of dry matter (DM) and nutrients during the ensiling process is unavoidable. However, during the process of harvesting and ensiling, there are choices to make and management practices to utilize that may minimize those losses.
These include, but are not limited to, the selection of an effective inoculant, the rate of fill of the bunker, the weight of pack tractors and the time spent on the pile, the size and management of the feeding face and the size, shape and type of bunker or pile.
Harvesting a crop at optimal moisture content can reduce the loss of DM and valuable nutrients. Harvested with too much moisture leads to losses in effluent, while harvesting with too little will lead to a restricted fermentation. Effluent is the moisture that can be seen seeping out of a silo. While some of the effluent is water, there is a considerable portion that is made up of the water-soluble nutrients found in the harvested forage.
This includes plant sugars, soluble proteins and some vitamins and minerals. These are the most readily digested portions of the crop, and losing them to seepage is something we want to minimize.
Similarly, if a silo is filled with a crop that is too dry, then the process of fermentation is restricted and the desired outcome fails to materialize. In a low-moisture condition, reduced amounts of plant sugars are available to be converted to acids. This results in a higher-than-optimal pH of the silage and a degree of instability of the material. Crops that are too dry are difficult to properly compact, thereby increasing the risk for high porosity of the silage. Opportunistic yeasts and molds begin to grow in the silage mass, resulting in an increased risk of aerobic instability.
Over the past four decades, effective inoculants have been well established as a tool to reduce the loss of DM from silage. In the 1980s and 1990s, Dr. Keith Bolsen of Kansas State University worked with inoculants in field scale applications and showed a 1% reduction in loss of DM with the use of a single strain of Lactobacillus plantarum.
This inoculant worked primarily by decreasing the time it took to achieve a desired drop in pH and subsequent preservation of the feedstuff. Since then, technological advancements enable us to select strains of organisms that not only improve the fermentation process but also provide in-use aerobic stability by preventing the growth of yeast and mold during feedout.
We also have the opportunity to select specific strains of bacterial species that either initiate a relatively fast start to the ensiling process, enabling an early use of the material, or that finish strongly and drive down the pH to a durably stable end point. With these effective inoculants, it’s common to see 3% to 5% improvements in recovery of DM from inoculated silages, well above the 1% expected previously.
Selecting the right inoculant is important. Equally important is the correct handling and application of that inoculant during the harvest. Dead and dying bacteria are of little value when proper bacterial fermentation is the objective. There are several critical control points that need to be properly adopted throughout the chopping and ensiling process. Doing so will greatly improve the chances of success.
Handling and application of the inoculant
1. Storage
It all starts with proper storage. Stabilized inoculants must be stored in cool, dry places and used prior to their expiration date. Inoculants that require refrigeration should be stored at low temperatures until harvest.
2. Proper mixing
A. It is essential that the inoculant is mixed as directed by the manufacturer.
B. Water temperature and quality should be monitored closely and addressed/corrected whenever necessary.
C. Mixing should occur as close as possible to the time of usage.
D. Any mixed solution should be used within 24 hours and, if not, it should be discarded.
3. Application
Keeping the bacteria in the inoculant alive during the application process is paramount to success. In most situations, we apply inoculant at the chopper as opposed to using an over-the-scale applicator. Although technology is improving, it is prudent to evaluate the use of water tanks integrated into the choppers. These internal tanks are often located next to a high-horsepower engine that radiates a significant amount of heat. If the motor is running, these tanks get hot.
At temperatures over 160ºF, some bacteria are going to die. Mounting an external applicator and keeping cooler packs in the water tanks can help minimize losses due to heat. In addition, it is important to:
A. Clean and maintain the applicators.
B. Use the correct size of nozzle that won’t clog during application.
C. Dial in the correct application rate based on the tons per minute being chopped.
D. Ensure that the application pump is turning on so the inoculant is actually being applied.
These last few items may appear to be obvious and simple, but attention to detail tends to go out the window when harvest is in full swing and we’re tasked to manage many things all at once.
Pile design and safety
Size and shape of piles and bunkers are key considerations with regard to optimizing the ensiling process and safety. Too often, we see oversized piles and bunkers that cannot be adequately packed during fill and can’t be fed out quickly enough to prevent losses due to aerobic instability.
There are two simple rules that if followed will improve the likelihood of success in this area:
1. Are we adhering to the rule of 800?
This refers to a calculation of the target packing weight, which equals the tons of fresh silage delivered per hour multiplied by 800.
2. Is the pile constructed to a size that enables the daily removal and use of at least 4 to 6 inches of the face?
A. DM losses can be minimized by using a defacer or rake to maintain a clean, even face. This leaves a flat face that minimizes the surface area exposed to oxygen.
B. This will also help prevent dangerous overhangs that can fall and fatally bury personnel.
If the answer to either of these questions is no, then we need to ask, “What can be done to correct these issues?” Calculate the weight of the pack tractor and adjust the fill rate accordingly. For too large a face, the options are often limited for bunkers, as the structure of the silage system is already in place. Splitting the bunker with additional walls to make narrower silos that can be fed across the face in a single day is one option.
This also gives us the ability to close bunker silos more rapidly, not waiting until the entire large bunker silo is full to cover and seal. Drive-over piles and ag bags give us the option of adding storage to take care of the additional silage.
While losses in DM are important, the biggest concern with improper filling is worker safety. Silos that are overfilled above the sidewalls can result in a much more significant loss, us or our employees. Every year, someone is lost in a silage-related accident. These deaths result from tractor rollover accidents during packing, silage avalanches from silos that are too tall or not defaced correctly and from silo gas when checking an upright silo. How can we reduce the risk of these losses happening? We can employ better safety-related planning and management practices:
1. Sizing our silos correctly and making sure the angle isn’t too steep can help reduce these risks. If we are faced with choosing between overfilling the silo or adding a drive-over pile, then choose to add the drive-over pile – it will be safer in the long run.
2. Upright silos: Before entering the silo, make sure to hook up the blower and clear out the gases.
3. Using the buddy approach when working with any type of silo is a good safety practice.
4. Sidewalls: Not seen often today and for good reasons – round bales used as sidewalls. The bales are simply not heavy enough to serve as good walls and represent a safety and DM loss nightmare. The lower weight can cause slipping while filling and packing the silo. This often means the sides are not packed as good as possible, increasing the DM loss in the silo.
A significant but avoidable loss is top spoilage. The amount of loss in bunker silos has been studied extensively and the addition of a cover has been shown to reduce loss of DM. Covering bunks and drive-over piles can significantly reduce the DM loss. We commonly hear, “There are only a few inches of spoilage.” What we really need to look at is where the silo was initially filled to and where did it settle during fermentation. This can provide an indication to how much shrink has occurred. Or try to note how much time is spent shoveling off the spoiled part – every day or every week.
When covering bunkers and piles with plastic, make sure it is sufficiently weighed down to keep it in place. If using ag bags, then be sure to check them on a regular basis for holes or wear. Economically important damage can come from birds and pests or from other physical insults. Using a good-quality tape designed for the application is critical when making repairs. These types of tape do not accumulate damage from UV radiation, and they seal against the plastic film of the bag significantly better than duct tape.
At feedout, we need to consider what is done with the spoiled silage or crud layer. Is it pitched off the silo or fed? Neither of these is an ideal option. The removal of the crud layer is a safety concern, as we are usually putting an employee in an unsafe position near the face of the silo to remove this layer. Feeding the spoilage is also an issue, as it can reduce DM intake and digestibility of the ration. If we prevent as much spoilage as possible, either by using a surface-applied inoculant designed to help prevent spoilage losses or use an oxygen barrier film or the combination of the two along with the tried-and-true plastic cover with tires, we can help minimize the spoiled layer in a silo.
Loss of DM is a natural consequence of making silage. However, it can be minimized by using best management practices at every point in the process from harvesting to feedout. Typically, reducing losses increases quality and amount – less loss, better and more feed – and it doesn’t matter if we are talking about corn silage for dairy cows or high-moisture corn for finishing beef cattle, the concept and principles are the same.
With the high value of harvested forages and feeds today, it only makes sense to invest the effort to do the job right. Remember: That extra attention to details in a few weeks of the season will impact a full year of everyday ease.
