What Is Baled Silage?

Baled silage is forage that is baled at a higher moisture than forage to be stored as dry hay - between 40 and 60 per cent, depending on its use as feed. Bales are then sealed with airtight plastic (either in a stack, as individual bales, or in a long tube) and kept in the same package until they are required. The high moisture and lack of air promote fermentation, which preserves forage quality.

Large, round bales have been the most popular form of baled silage in Manitoba - but medium-sized, square bales are now coming into popularity because they are easier to transport and to market.

Baled silage was first harvested in Manitoba at a 1975 Eastern Grassland (EGS) demo at Rosa, and is now very popular with Manitoba forage producers. Why? Because it is a practical method of reducing harvest and storage losses in the high-quality forage that our soils and climate can produce.

In Europe, too, baled silage is popular; it is estimated that at least 20 per cent of that continent's silage is harvested as baled silage.

Feeding Benefits

Baled silage is an excellent feed option, especially for backgrounding calves, because it has improved palatability over most feeds - due to the soft texture. It also reduces bloat and other digestive problems that occur with fresh alfalfa or alfalfa hay.

The increased palatability of baled silage also results in less waste compared to dry hay, when it is fed in traditional round-bale feeders. In fact, a Manitoba Agriculture comparison trial found a 25 per cent feed saving over hay when both kinds of feed were used in this type of feeder.

Baled silage is readily adaptable to most dry hay systems (such as round-bale feeders) and can be unrolled in the field with less leaf loss than dry hay. It can also be chopped and fed on its own - or used in a variety of different feeding systems.

Baled silage can differ greatly in quality, depending on the type of forage used, the stage at which it is harvested, and how well it has been fermented. A University of Manitoba trial showed vast differences in animal performance and amount of feed required, when it compared low, medium and high quality baled silage (see chart below).
 

Baled Silage Performance Based on Forage Quality

The Fermentation Process

Silage preservation depends upon fermentation - which must take place in an airtight storage environment.

It is extremely critical that plant respiration (use of oxygen to produce carbon dioxide) called the aerobic phase - be stopped as soon as possible. This is achieved by making firm, dense bales that are then wrapped air tight. If air gets into the system during the aerobic phase (through tears in the plastic or because of loose bales), mould will develop.

Once there is no respiration taking place (and no air getting in), the anaerobic phase begins. This is when the lactic acid bacteria that are present in the forage ferment the carbohydrates (plant sugars), resulting in the production of lactic acid. Acetic acid and propionic acid are also produced.

The supply of carbohydrates will affect fermentation. For example, crops such as corn or grass, which have high levels of carbohydrates, will ferment easily. Alfalfa, on the other hand, has a lower carbohydrate level and takes longer to ferment. However, a late-fall harvest of alfalfa will usually contain higher amounts of carbohydrates - and will provide more-active fermentation.

Fermentation will stop between two to four weeks (depending on the crop), when acid levels increase and pH levels decrease - to a point where fermentation is no longer possible. At this point, the stable (storage) phase begins.

The pH levels, which are an indication of silage storage life, should be requested when feed is analyzed. If pH is above five, storage life will likely be short and forage should be used before spring. On the other hand, pH below five will most likely have a longer storage life.

Baled Silage Versus Chopped Silage

Research indicates that baled silage has a slower fermentation rate than chopped silage. This may be because plant juices produced by chopping are more readily available for fermentation, whereas plant juices from the long fibre of the whole plant (in baled silage) are released more slowly. Another reason may be that the surface area available to bacteria (for fermentation) is less with baled silage.

As the chart below shows, it could take up to 60 days for baled silage to drop to the same pH level as chopped silage can reach in one day. This drawback can be improved, however, by some of the new baling equipment now available, which will slice the forage as it is being baled.

Although it ferments more slowly, long-fibre silage may be more digestible than chopped (short-fibre) silage. Research shows 90 per cent digestible energy with baled silage, compared to 69 per cent with chopped silage.
 

pH Levels - Baled Silage Versus Chopped Silage

Fermentation Tips

• Ensure bales are dense and forage is well sealed, in order to cut down the amount of air in the system. This will reduce the length of the aerobic phase (to ensure good fermentation) and will prevent mould.
• Bale only the amount of forage that can be hauled/sealed in a day. In hot weather, the forage temperature will rise quickly and fermentation of unwrapped forage could begin within a few hours which could result in heat damage and lower digestibility.
• Avoid any manure contamination, in order to keep undesirable bacteria out of the system.
• Avoid raking the swath, if possible, in order to prevent contamination by soil organisms.
• Try and avoid using hay that has been rained on because it has a greater potential to be contamination by soil organisms.
• Avoid mature forage because of low sugar content that will result in poor fermentation. As well, crops at this stage have stiff stems which are difficult to pack and could puncture the plastic.
• Use a lactobacillus bacteria inoculant to improve fermentation - particularly in alfalfa. Agriculture and Agri-Food Canada research has shown this type of inoculant could improve livestock intake by five per cent, and daily gain by 11.6 per cent.
• Apply propionic acid or anhydrous ammonia, at amounts of one to two per cent of the dry matter, to prevent mould growth in lower-moisture forage moisture levels (25 to 35 per cent at harvest).
   

Anhydrous ammonia can be applied to lower-moisture forage to prevent mould. Shown here is a stack of covered bales, but this technique can be used with individually-wrapped bales and bales in a tube.

Moisture - the Critical Factor

The right forage moisture level is one of the most important elements in a baled silage system. A minimum of 40 per cent moisture is required for fermentation - although moisture content can range from 40 to 60 per cent, with a targeted average of 50 per cent.

Most farmers prefer forage to be on the drier side, as the bales are easier to handle. However, the drier the forage, the more dense and firm the bale should be in order to avoid air pockets.

Moisture below 40 per cent will make it difficult to get a firm, dense bale and will result in minimal fermentation and increased risk of mould. With this type of forage, an airtight seal is critical if is to be maintained until feeding time with minimal reduction in feed quality. Even though it will not change color, it should be used over the winter before the return of warm weather, as it has the potential for heat damage.

Moisture in excess of 60 to 70 per cent will result in heavy bales (see chart below) that have a potential to sour (due to excess butyric acid) and freeze in storage. There will also be more effluent (liquid waste from the fermentation process) at the bottom of the silage bags or stack.

The wilting period - the time between cutting and baling - of the cut crop is very important in achieving the right moisture level for fermentation. The objective is to bale the crop as soon as it drops from 80 per cent moisture (the usual moisture content of a standing crop) to 50 or 55 per cent - which will happen very quickly, especially in warm weather. Delays will result in dry matter losses due to respiration, as well as leaching of soluble carbohydrates if it rains.

Moisture for good-quality silage should come from the plant - and not from dew or rain. Forage that has been dried for hay, and then received rain before it's been baled, will usually produce poorer-quality silage.
 

Bale Weight at Varying Moisture Levels

Harvesting Management

The first hay cut is usually a priority for making into baled silage. Using this first cut is a good management technique, because it allows the season's hay harvest to begin on time (no need to wait for ideal weather, or for the crop to dry). As a result, subsequent harvests will be on time - and quality can be controlled.

Other priority crops for silage baling include green feed/high-moisture crops which are often difficult to dry, surplus forage not required in a grazing system, and third-cut/late-fall harvests that are cut under cool conditions and at high moisture levels. The latter will produce especially good silage because the sugar levels are usually quite high.

The crop should be cut leaving a high stubble, in order to avoid the soil-contaminated parts of the forage - which are also lower in feed value.

Swath size should be as close as possible to the width of the baler, in order to ensure bales are even and to avoid barrel-shaped bales - which are difficult to wrap and may allow leaks into a tube wrap system. If the ideal swath size is not possible, a good weaving pattern should be used to produce even bales.

A wide swath size is also important to promote rapid dry down of the crop - as is a good crimping system.

Note that when baling, plastic twine is preferred over sisal twine for securing bales, as the oil-based preservatives in the sisal may degrade the plastic once the bales are wrapped.

Bales should be wrapped within two hours of baling at higher temperatures (22 to 30 degrees C), and within four to 12 hours when baled at lower temperatures (10 to 15 degrees C).

Baling Options

Round Balers

Round balers are most commonly used for baled silage - with hard-core or variable-chamber balers being the most popular. They can produce firm, dense bales that can be varied in size to match the forage moisture content and the hauling equipment. However, some cannot handle the moisture - so it is wise to check with your dealership. A soft-core baler should be used only if it can produce a firm bale.

Round-silage balers are now available, and come with special features that have been designed especially for baled silage production. Some have scrapers that clean the rollers when they become clogged with high-moisture forage, and most have cutting attachments that slice the forage as it is being baled. Slicing aids in fermentation and makes the feed easier to include in mixed rations. An eight-inch cut is recommended when using this attachment, even though it can usually be set anywhere between four and eight inches.

Square Balers

Medium-square balers are gaining popularity because they produce bales that are more practically sized for moving and marketing. As well, they have high capacities. Some units now come with forage slicers, and are being used for silage harvesting.
 

Small-square balers are seldom used for silage production because it is too impractical to wrap and store the size of bales produced by this equipment.

Hauling Equipment

Most bale-hauling equipment can be used with high moisture bales in a baled silage system - provided bale weights are not too excessive. Loaders, trailers, etc. need to be tested to ensure they can handle the heavier weights.Medium-square bales are gaining popularity.

Storage Options

Stack System

With this system, large-round bales are stacked in a pyramid formation - two or three bales high. Medium-square bales are stacked on top of each other, also two to three bales high. The stack width is determined by the width of the plastic used to cover it, although 40 by 100-foot black plastic is usually used. Plastic should be a minimum thickness of six mils.

Plastic is sealed to the ground using sand, manure or soil - although manure is preferred because it does not contain sharp objects to tear the plastic. As well, manure tends to pull the plastic tight - and there is usually a good supply of it on hand. Plastic must be well sealed and tight; loose plastic whipping around in the wind will develop tears to allow air in, and will also act like a bellows to pump air in.

Once plastic is sealed, surplus air can be pumped out using a shop vac - or similar pump. However, if forage is above 50 per cent moisture, respiration will utilize the surplus oxygen in the system.

Tube Systems

There are a number of tube systems to choose from, which all involve moving the forage bales through a hoop and into a folded plastic tube attached to the hoop. Plastic needs to be at least four mils thickness, and should have sufficient ultra violet resistance. Most plastic in these systems is white, and quite often has a black liner for increased strength and protection from the sun.

With a home-made tube system, bales are manually pushed through the hoop and into the folded plastic. The hoop is moved forward to accommodate the next bale - creating a tube of wrapped bales behind it. Care must be taken to "anchor down" loose plastic - a common disadvantage with this system. As well, this method is time consuming.

The tube-o-lator system is an automated version of the home-made system. Specialized equipment uses guides to raise the bales so they can be moved through the ring, and into the plastic tube folded around the ring. The hoop starts at the end of a row of bales and keeps moving forward, leaving a long and sealed tube of silage behind. An adjustable ring allows for a tight fit of the plastic - a major advantage to this system. As well, this equipment can tube bales very quickly up to 200 bales per hour.

Other tube systems use hydraulic equipment to push the bales through the hoop and into the plastic. There are often hydraulic fingers to stretch the plastic and give it a tight fit.

Individual Bale-Wrap (Stretch-Wrap) System

This system involves equipment that individually and evenly stretch wraps (with controlled tension) each bale with four separate pieces of plastic wrap. Plastic film must have a 50 per cent stretch factor, be resistant to ultra violet light, have a good tear strength, and be able to adhere well. White is used for high sunlight areas and black for lower sunlight areas.

A commonly-used system in Europe, it produces minimal silage spoilage because of the tightness of the wrap. Another advantage is that bales can be moved for storage, and can be stacked in small storage areas.

Square-Bale Individual Wrap

A relatively new system, this one involves equipment that stretch wraps plastic (same type as used in individual wrapping of round bales) around individual square bales. Bale length is adjusted to accommodate desired bale weight and wrapping equipment - usually four to five feet in length instead of eight feet.

Tube-Wrapped System

This system uses equipment that places a bale on a platform, hydraulically moving it through a revolving ring that stretch wraps four layers of plastic around it. The bales are encased in the wrap, as opposed to being placed into existing tubes (as with the tube systems). However, like the tube systems, it creates long tubes of wrapped bales, which can vary in length. Plastic wrap specifications are the same as for the individual bale wrap (stretch wrap) system.

The tube wrap is similar to the individual wrap system, but over 70 bales can be processed in an hour. The wrap is just as tight, but it uses one half of the plastic.

Storage Site Recommendations

• Ensure baled-silage storage site is well drained.
• Ensure site is free of long grass, in order to reduce rodent problems.
• Do not allow debris to collect in the area; it could puncture the plastic.
• Locate bale stacks, if possible, in a wind-sheltered area - in order to reduce wind damage to the plastic. Wind whip can quickly wear holes in the plastic, and it will act as a bellows to pump air into the system.
• Set up rows or stacks, where possible, with ends in a north-south direction. If they are set in an east-west direction, the sun's warmth on the wide expanse of southern exposure in the winter can cause moisture to migrate to the north side of the tube or stack. As well, the warm south side will attract rodents.
• Check all wrapping regularly to ensure there is no damage to the plastic seal. If the plastic is punctured or torn, use red construction tape to repair the damage.

Advantages of Baled Silage

• Requires one-half to one-third the drying time of hay - only 13 to 20 hours, as opposed to 40 or more for dry hay.
• Permits harvest at optimum stage for high-quality forage.
• Provides flexibility in amount harvested, so that small amounts can be handled.
• Allows for a producer-controlled cutting schedule - first cut at the optimum time, and subsequent cuts when quality is highest.
• Provides the opportunity to utilize weeds, green feed or late-cut forage that are difficult to harvest as dry feed.
• Lowers leaf loss in the field by 5 to10 per cent (from 25 to 30 per cent for dry hay), resulting in minimal dry matter loss in harvest and storage.
• Uses the same harvesting equipment as dry hay bales - a major advantage for capital expenditure reduction.
• Requires less labor and less energy for harvesting than a chopped silage system.
• Allows for easy and inexpensive expansion of production; bale wrapping is not a limiting factor.
• Retains a more-natural green color than chopped silage (due to lower temperatures) - a plus for the horse-feed market.
• Has less leaf (dry matter) loss than dry hay when fed.
• Decreases feed loss because of better palatability over dry hay.
• Produces less digestive disturbances (such as bloat) than dry hay.
• Can be easily shredded so that it can be used with other kinds of feeding systems.
• Increased market acceptance because of potential as a higher quality feed with greater palatability, resulting in increased dry matter intake.
• Popular with horse farms because it lowers respiratory problems often associated with dry hay.
   

Disadvantages of Baled Silage

• Can spoil if air leaks into the plastic; rodents, birds, pets, wind and hail all have the potential for producing holes (and spoilage).
• Low-moisture forage (less than 40 per cent) will not ferment, and has a fairly high risk of developing mould.
• High-moisture forage (above 70 per cent) will produce sour silage and has the potential for producing harmful by-products.
• Animal performance may not be as good as with chopped silage (according to some research), although other research suggests baled silage is more digestible.
• Annual cost may be higher than chopped silage due to cost of plastic. However, total capital cost can be similar as it is the only harvesting system required (no extra equipment needed for another system).
• Storage life is shorter than that of chopped silage.
• Tube and bale-wrapping equipment requires additional capital expenditures. (However, a smaller operator can custom contract wrapping services.)
• Used plastic must be hauled to a landfill site, although some local governments are now developing recycling programs. (Plastic should not be burned, as it produces toxic fumes.)
• Bale weights increase drastically as moisture increases
• Bale size may be too large for handling equipment - particularly for smaller equipment such as front end loaders - and size must be adjusted.
• Bales with high moisture or minimum fermentation have higher potential for freezing.
• If used in outside feeders, open bales must be used up within three days to avoid freezing in cold weather.