Many farmers preserve forage as dry hay, but for some, baleage is a good alternative.
Depending on storage conditions, losses in baled dry hay stored outdoors is between 10% and 30%, while properly wrapped baleage should have almost no quality loss. Storage for baleage is less costly than a chopped silage system, which requires a silo or a bunker.
Rory Lewandowski, Ohio State Extension educator, says baleage is a hybrid system that combines baling with ensiling. "You're baling at a higher moisture content than dry hay, then wrapping it in plastic," he said. "Our goal with this system is to produce a really high quality, highly palatable fermented forage."
Baleage minimizes unpredictable weather disruptions, and it's often the only option if conditions are excessively wet. Baleage is also a good choice for storing autumn forage when shorter days don't allow for adequate hay drying.
It's possible to cut forage for baleage and bale it soon after mowing. Because baleage is baled at a higher moisture content, quality is higher because there's less leaf loss and shatter from raking, tedding and baling. Baleage uses much of the same equipment as a dry hay system.
Several negatives with baleage include the need for determining moisture throughout the harvest and storage process. Plastic wrap disposal can be problematic - only a few places offer recycling programs. Because baleage is a fermented product, farmers must be able to plan and manage feed out.
Although specialized equipment is needed for wrapping, many farmers rely on custom operators for this step. High moisture content means heavy bales, which requires equipment that can handle extra weight.
A multi-stage fermentation process is involved in achieving a stable final product. "When we start with fresh forage, there's potential for desirable and undesirable microorganisms," said Lewandowski. "We want to get the forage into an anaerobic state and kill or render dormant undesirable bacteria and yeast that cause mold and spoilage. We want to make sure anaerobic bacteria have the advantage so they can convert plant sugars to acids and drive down the pH."
Desirable fermentation includes a short anaerobic phase to minimize the loss of plant sugars so those desirable anaerobic bacteria can convert them into lactic and acetic acid and to drop the pH below 5.0. The product should have a pleasant odor and eventually, good bunk life. Lewandowski said it takes at least 14 days before baleage is stable.
Temperature is driven by both moisture and the amount of air present. Lewandowski compares this aspect to composting that reaches high temperatures. It's important to manage temperature to avoid a Maillard reaction, which occurs at around 120º F. This reaction results in caramelization, converting crude protein to non-available protein. Animals may be willing to consume such a product but it doesn't have the quality desired to achieve good performance.
Legumes and grasses differ significantly in lactic acid production. "The production of lactic acid is required to drive the pH down," said Lewandowski. "That's the reaction we want to dominate in a fermentation process."
Compared to grasses, legumes have a lower sugar content and a high buffer capacity to help resist pH changes. Lewandowski said legumes leave little room for error, so grasses work better in most silage systems.
While more mature stands produce more tonnage, quality goes down. Mature stands are highly stemmy, which means increased fiber content along with lower plant sugars and starches. With increased fiber content, it's more difficult to get good fermentation that results in higher quality product. Excess stemminess makes it more difficult to get a dense pack, which lowers the chance of good anaerobic activity. Drier forage material requires more plastic wrap to exclude air and promote a good anaerobic environment.
Other factors that affect baleage quality include maturity. "We can't improve forage quality with fermentation.," said Lewandowski. "We can affect palatability, but we are never going to have better quality than the day the forage was mowed."
Moisture content in ensiling is a driving factor for baleage quality. Baleage that's too wet results in quality issues. The goal for moisture is 50% and is key to good fermentation. Excess moisture (65%+) can cause a "sour" fermentation, which can result in clostridial fermentation and higher risk of botulism.
Good quality baleage requires uniformly packed, dense bales, which is a matter of excluding air. If forage is cut at the correct maturity stage, density is the next critical factor. Lower tractor speed with faster PTO speed promotes dense bales.
"Bale density has an impact on bunk life," said Lewandowski. "Once we open a bale, oxygen is the enemy. Some of the undesirable organisms that might have been dormant will start generating molds and spoilage, which affect bunk life."
Another quality point is wrapping bales with sufficient plastic as soon after baling as possible. Wrap within several hours but no more than 24 hours after baling to preserve sugars that bacteria will convert to usable nutritional assets.
Delaying wrapping prevents adequate fermentation, resulting in higher baleage pH. Research shows that bales should be wrapped at least six times with 1 ml plastic to adequately preserve baleage. This prevents heating and helps initiate anaerobic fermentation.
Drier and mature forage require more plastic layers. This is due to lower sugar content and because older forage is stemmier and can poke through plastic.
Lewandowski pointed out key differences between baleage and silage: "Baleage takes longer to ferment," he said. "It's because we're not chopping the forage - we're baling long stems. Chopping releases sugars so bacteria have better access to sugars, which allows a more complete fermentation. Baleage may not be packed as tightly as chopped forage, and extended respiration time may slow fermentation. Again, the goal is a short respiration time and a rapid drop in pH.
"The closer we get to mimicking some practices that result in a high-quality chopped silage, the better the product will be," said Lewandowski. "But it's never going to go through the same amount of fermentation as a chopped product."