Quality silage starts with good management

Moisture

Forage moisture plays a critical role in a successful ensiling process. When forage moisture is too low, it is difficult to pack the ensiled material. As a result, air can remain trapped within the forage mass. This encourages yeast and mold growth, which leads to excessive heating and loss of DM.

Extremely high temperatures, (> 46°C/115°F), which can occur when oxygen is trapped during ensiling, can bind proteins in the forage to carbohydrates, and make both unavailable for digestion and absorption by cattle. This protein binding reaction occurs most commonly in alfalfa haylage. In addition, moldy silage can reduce the livestock’s resistance to infections, and can contain mycotoxins.

Silage that is too dry and has heated extensively often has a dark-brown to black color and a burned, tobacco-like odor. If moisture is below recommended levels, it might be necessary to add water at ensiling, although this is usually difficult to do because of the large amount of water required.

Forage that is ensiled too wet can result in effluent (i.e., runoff or seepage). Effluent can be prevented or minimized if the DM content is at least 32 percent in bunker silos and 35 percent in tower silos. Effluent contains about six percent DM and includes water-soluble carbohydrates and proteins. These nutrients are not only lost for the fermentation phase, but represent a loss in nutritional value of the silage. The lower sugar levels can increase the risk of a clostridial fermentation, while protein loss means the producer will have to spend additional money for a protein supplement.

Ensiling at the correct moisture also creates the best environment for LAB in the fermentation phase. Recommended moisture ranges vary for different crops and silo types (Table 1).

Maturity

Stage of maturity of the forage crop at harvest is an important factor in determining nutritional value. Maturity affects both silage yield and quality. Forage yield usually increases with advanced maturity, while nutritional value usually decreases. Recommendations for the correct stage of maturity vary with different crops and silo types (Table 1).

It is generally recommended to harvest whole-plant corn when the milk line is one-half to two-thirds of the way down the kernel. At this point, the moisture of the whole plant will normally be 64 to 68 percent. This makes packing easier, and assures adequate fermentable sugars for the LAB and maximum energy value for livestock. Because corn should be ensiled in upright or oxygen-limiting silos at a lower moisture range, whole-plant corn can be more mature under these conditions.

Recommended maturity for alfalfa is the mid-bud to early bloom stage. A delay in harvesting decreases protein content and increases acid-detergent fiber and neutral-detergent fiber values. This, in turn, negatively affects the relative feed value of the forage.

Weather

Weather conditions at harvest are a major concern for alfalfa, but less of a concern for corn. Alfalfa contains 75 to 80 percent moisture at cutting, and should always be wilted in the field before ensiling to prevent effluent and potential clostridial fermentation. The amount of time required to wilt alfalfa depends on the weather. Warm and windy conditions should dry the forage to about 65 percent moisture within four to six hours. If temperatures are cool or the humidity is high, the wilting period is prolonged.

The longer the wilting time, the higher the DM and nutrient losses will be. This is due to plant respiratory enzymes and undesirable microorganisms utilizing plant sugars, which otherwise could be used by beneficial LAB. Alfalfa that is too dry is prone to excessive heating in the silo and has lower nutrient digestibilities, as well as higher mechanical losses in the field. Very dry haylage (< 45 percent moisture) can lead to excessive heat damage and has the potential for spontaneous fires in the silo. Because grasses and small grains wilt considerably faster than alfalfa, good drying conditions are a lower priority when harvesting these forage crops. Chop length

Forage that is chopped at the recommended length (Table 2) promotes good packing, faster air exclusion, and even distribution in the silo. Forage that is chopped too coarse is difficult to pack and traps oxygen. This can result in excessive heating from a prolonged aerobic phase and increased yeast and mold growth. Large forage particles also might be more difficult to unload and might be a problem in rations.

Generally, higher DM forages require shorter chop lengths because they are more difficult to pack. Cutting forages too fine, however, can lead to a lower milk fat level, less rumination, and a high incidence of displaced abomasums and rumen acidosis. A general recommendation for alfalfa is to chop so that 15-20 percent of the particles are more than 1.5 inches long.

To insure correct chop length, properly adjust harvesting equipment and regularly sharpen knives. Dull knives tear forage, which contributes to excessive effluent and loss of nutrients. Worn knives also can be a safety hazard.

Forage additives

Several different forage additives are available to minimize loss of nutrients and help produce high quality silage. These additives include bacterial inoculants, enzymes, acids, and carbohydrate and nonprotein nitrogen sources. Described on page 12, are common types of forage additives and their advantages and disadvantages.

Bacterial inoculants

Of the various types of silage additives available, bacterial inoculants are the most widely used. A silage inoculant should contain live, homofermentative lactic acid bacteria and should provide at least 100,000 Colony Forming Units per gram (CFU/g) of wet forage.

When good silage management is practiced, inoculants have been shown to consistently improve the nutritional quality of silage, and to provide a substantial return on investment. Inoculants help insure that forage is properly fermented, and nutritional value and palatability are maximized.

Lactobacilli and pediococci are the most common bacterial species in silage inoculants. Both are efficient producers of lactic acid, which is needed for a fast drop in pH. It should be recognized, however, that genetic diversity among LAB causes differences in response between different strains of the same species. Strains can differ in their ability to utilize certain substrates and to proliferate at various pH and temperature conditions.

Two basic types of inoculants are available: water-soluble and dry granular. Water-soluble inoculants are supplied as a concentrated powder that is mixed with water prior to application. Once mixed, use the inoculant mixture within 24 hours to insure effectiveness. Water-soluble inoculants are usually packaged in bottles or pouches. Dry inoculants are applied directly to forage and are generally packaged in 20 or 50 pound bags.

In university studies, DM recovery for inoculated silage is consistently greater than for untreated silage. Studies show that inoculated silage undergoes a more efficient homofermentation, which can lead to improved milk production, weight gain, and feed conversion.

In a two-year dairy study at the University of Wisconsin, higher DM intake of inoculated haylage resulted in greater milk yield. Daily milk production for cows fed inoculated haylage was five pounds greater than for cows fed untreated haylage.

The study showed that a dairy producer with a 250-cow herd potentially could earn additional net income of more than $11,500 per year by using a silage inoculant (Table 3). As herd size increases, potential income increases as well (Figure 1).

A Kansas State University research trial showed that a microbial inoculant improved corn silage fermentation, which resulted in better steer performance. Dry matter recovery of inoculated silage was greater than untreated silage. Steers gained 7.9 pounds more weight per ton of inoculated silage consumed than steers consuming untreated silage.

Applicators

A uniform distribution of a bacterial silage inoculant on forage is important for maximum product effectiveness. Many types of applicators are available for water-soluble or dry inoculants. Use an applicator attached to the forage harvester to insure immediate, uniform inoculation prior to ensiling.

An applicator mounted on the blower is commonly used for filling upright silos. Inoculant can also be sprayed or sprinkled on top of each wagon or truckload of forage prior to unloading, or after the forage is dumped into trench or bunker silos prior to packing. However, this method is not recommended and should only be used as a last option.

Storage structures

Conventional upright silos, oxygen-limiting silos, plastic bags, wrapped-bales, and trench, bunker, or drive-over pile silos are all used as structures to ensile forages. High quality silage can be made successfully in any of these storage structures when good forage management is practiced. The decision on which type of silo to use depends on the crop, available labor, capital investment, feeding management, herd size, and personal preference.

Conventional upright silos

The shape of an upright silo offers vertical pressure for good packing, and exposes less silage surface area during feedout than other silo types. Conventional silos are well suited for storing 1,000 tons or less of silage.

Upright silos and their filling and unloading equipment require regular maintenance. Make sure walls are not cracked, and doors fit tightly to keep out air and moisture. The silage surface should be sealed with plastic after filling to reduce spoilage.

Oxygen-limiting silos

Oxygen-limiting silos minimize air infiltration into ensiled forage. Because these structures unload from the bottom, they can be refilled during feedout, and no minimum amount must be fed each day to avoid spoilage. Some air, though, will inevitably enter at the unloading ports. Because air infiltration is limited in these structures, many producers believe an inoculant is unnecessary. Research shows, however, that inoculants can improve nutrient preservation in forage ensiled in oxygen-limiting silos.

Bunkers, trenches, and drive-over pile silos

These silos are commonly used to store large volumes of silage (more than 1,000 tons). These horizontal structures, however, need to be filled as rapidly as possible, packed adequately, and sealed immediately to minimize aerobic spoilage.

Bunker silos are constructed above ground or slightly below ground. They usually have concrete floors, with walls of concrete, wood, or other material.

A trench silo is a ditch in the ground that often slopes gradually to the front. It is popular in areas with moderate climates and well-drained soil. Trench silos can have floors and lined walls, but often are constructed solely from earth that is smoothed along the bottom and sides.

Plastic bags

Plastic silo bags provide a flexible storage system, require a relatively small investment, and are a good alternative to conventional structures. Many producers have had success with all types of forage crops and high moisture grain in silo bags. Disposal of the used plastic can be a concern.

Packing forage in bags can be inconsistent because there is no vertical pressure applied. Use an inoculant to help promote good fermentation in silo bags where packing pressure is not ideal. Be sure the moisture level is in the recommended range for the forage.

Wrapped-bale silage (balage), popular in Europe, also offers lower capital investment and labor requirements compared with other systems. High-density round bales, each weighing 600 to 1,200 pounds, are wrapped in plastic film, or stacked and covered with a plastic sheet. Limited research indicates that silage quality can vary widely among bales. Spoilage and excessive surface waste are the main challenges to producing silage in this type of storage system.

Filling, packing, and sealing

Perhaps more nutrients are lost when silo filling is prolonged than at any other area of silage management. Regardless of silo type, filling, packing, and sealing should be completed as quickly as possible to achieve anaerobic conditions necessary for optimum fermentation, storage, and feedout.

During filling, always distribute forage evenly and in thin layers. In upright silos, use a distributor to avoid separating coarse and fine forage materials. In trench, bunker, or drive-over piles, use a heavy wheeled tractor that travels back and forth over each layer of forage.

Storage in bunkers

Step 1

Sidewall sheets

Use Silostop Wall Film on sidewalls before filling to:

* Reduce the risk of wastage at shoulders

* Ensure a good seal between top sheet and sidewalls

* Divert water run-off away from silage

* Protect side walls from damage

Apply Silostop Wall Film to sidewalls, allow for at least one metre at floor level and a one metre overlap on the top surface.

Use forage at the foot of the walls to hold the Silostop Wall Film in place.

Once filled, pull Silostop Wall Film over the forage before placing the top layer and adding Silostop Gravelbags to seal and weight the bunker.

Step 2

Fill with chopped forage

When filling, aim to achieve a high compaction density of at least 240kg dry matter per cubic metre (15lbs dry matter per cubic foot). Shape all surfaces so water drains off the back, front and sides. Slopes should not exceed an incline of 1 to 3.

Fill in continuous thin layers of forage which do not exceed 15cm (6 inches). Avoid driving over large lumps or thick layers of forage during filling. If filling after a break (e.g. overnight), do not re-compact the surface as this allows more air to enter the packed forage.

Do not spend time compacting the last few loads excessively. Compact them the same amount as all the other loads and cover immediately.

Step 3

Cover forage with Silostop Film

After filling the bunker and compacting the final forage surface, cover with Silostop Ultimate Oxygen Barrier Film.

Silostop Film should be overlapped on all joins to prevent entry of water and air. When using Silostop Gravelbags, the joins should be overlapped by at least 1m (3 ft) of film. If tyres are used, the overlap should be at least 1.2m (4ft). Use a solid row of Gravelbags or a double row of tyres or truck sidewalls on all joins.

Silostop Film should NOT be pulled tight but allowed to follow the contours of the forage surface. If you need to walk on Silostop, please do so with care.

Step 4

Protect Silostop Film

Silostop Ultimate Oxygen Barrier Films are very strong. However, they can be pierced by sharp objects, and should be protected from physical damage with a robust cover. Any air entering through holes will affect the quality of the silage.

Silostop offers two covering products:

* Silostop Anti-UV Cover, which should be used to cover Silostop Orange Film.

* Silostop Open Net, which can be used to cover Silostop Black Film. Silostop Open Net should only be used to protect Silostop Orange Film if an additional layer of conventional black / white-on-black PE plastic is applied over the Silostop Orange Film to give UV protection.

Step 5

Seal and weight

When using Silostop products, Silostop Gravelbags should be used to secure and weight the covers.

Emphasis must be placed on sealing the edges and joins by using a solid row of Gravelbags, or at least two solid rows of car tyres or truck tyre sidewalls. There should be no gaps where air can enter.

Silostop Gravelbags

When using Gravelbags, tyres can be eliminated altogether. Place a solid row of Gravelbags along all outside edges and joins. Place rows of Gravelbags approximately 4 to 6 metres (13 to 20 feet) apart.

Place Gravelbags on top of the Protective Net in a position where they also weight and secure the joins of the film to prevent entry of air at joins and edges.

• Approximate weight of a filled Gravelbag is 20kg (45 lbs) • Effective length of a filled Gravelbag is 1 metre (3.3 ft)

Tires

If the is no alternative but to use tires or tire sidewalls instead of Gravelbags, cover the entire surface of the forage with each tire or tire sidewall touching the next. Consider using touching tires with Gravelbags on the outside edges to improve the seal.

Step 6

Feedout

For optimal feedout, use Silomats on the leading edge of the cover above the feedout face. As the silage is removed from the face, Silomats can be moved back, keeping the front of the covering secure and to prevent lifting.

Alternatively keep a solid row of Gravelbags on the leading edge of the cover to ensure that air does not travel under the Silostop film. Do not walk close to the edge of the exposed feedout face or operate with your back to the edge of the face.

Protective nets can be folded and put away ready for next season while leaving the cover in place.

Stack and store Silomats and Gravelbags on pallets for easy handling.

Learn more:

To learn more about harvesting and storage of high-quality forage, contact (add hyperlink to Contact here) your MojoMoo representative who can help ensure you are maximizing your time, effort, and investment.