Understanding Baleage Terms and Observations

Baleage is a beneficial option for making high quality stored forage in Kentucky. Baleage is the ensiling of wilted forage in round bales wrapped in UV-resistant, stretch wrap plastic. The technology is well proven but not without its challenges. The primary challenge is  achieving a moisture content (MC) in the target range of 40 to 60%. Baleage is not ideal for ensiling for many reasons, but especially because the fermentable carbohydrates are on the inside of cells and must diffuse out to come in contact with the fermenting bacteria on the surface of the plant. For this reason, fermentation reports will often flag baleage samples as high risk because they will have low lactic acid values and pH above 5.0 compared to chopped haylages at similar moisture levels.

An on-farm research study in Kentucky over the past three years collected data on the fermentation characteristics of over 100 lots of baleage with MC ranging from 20 to 80%. As a result of studying these samples and the associated production practices, what follows is a guide to interpreting baleage fermentation reports.

Interpreting the terms on a fermentation report

· Moisture/Dry Matter – The moisture content of the forage as tested. The MC of baleage should fall between 40 and 60 percent to be conducive to fermentation and to inhibit the growth of Clostridial bacterial.

· Crude Protein – The estimate of the protein value of baleage, calculated by measuring nitrogen (N) content and multiplying by 6.25.

· Lactic Acid – The product of anaerobic fermentation of soluble sugars and carbohydrates by lactic acid bacteria such as Lactobacillus plantarum. Lactic acid values of 3% or greater are desired in baleage (DM basis).

· Acetic Acid – Concentrations of acetic acid should be between 1 and 4% (DM basis) and ideally no more than half of the lactic acid present.

· Propionic Acid – Propionic acid levels should be less than 0.5 to 1% (DM basis). High levels indicate that insufficient sugar was available for fermentation.

· Butyric Acid – Butyric acid should be no more than 0.5% (DM basis) and ideally less. Cattle intake has been shown to be depressed by as little as 0.3% butyric acid.

· pH – Ideally baleage should have a pH of 5.0 or below to inhibit secondary fermentation by Clostridial bacteria.

· Ash – is the fraction of the forage that is inorganic minerals. Standing forage is about 8 to 10 % ash (DM basis). Elevated ash content (>11%) indicates that the baleage has been contaminated with dirt.

Observations are important

To assess the quality of baleage fermentation, your observations can tell you a lot. Good baleage will not have an off odor, while butyric acid baleages can have a very putrid odor. Bales that squat or that have effluent seeping out are likely excessively wet and have undergone undesirable fermentation. Finally, bales that have holes in the plastic, particularly those formed soon after baling will lead to poor fermentation in that area and even botulism. To assess the damage caused by holes, it may be necessary to take multiple samples at and around the damaged area. It is far safer to discard bales where the holes have allowed significant air infiltration. The worst case of botulism I ever encountered came from feeding from a row of bales wrapped with an inline applicator that had a significant gash in the plastic mid-row. Cows did not experience a problem until they reached the compromised baleage.

Baleage is a valuable option to allow harvest of high quality feed while avoiding rain damage. Even though ensiling parameters for baleage are generally less desirable than chopped haylages at the same moisture content, a fermentation analysis plus careful observation can be very helpful. Baleage with MC between 40 and 60%, cut at early maturing, baled tight and wrapped with six layers of plastic will generally ferment well enough to be stable through one feeding season. High moisture, elevated butyric acid levels, ammonia N above 15% (as percent of total N), ash content above 11%, bad odors and holes in plastic are all indicators that baleage has a high probability of causing feeding problems, even botulism. ~ Dr. Jimmy Henning, for Hay and Forage Grower