Heulage

Heulage is a preserved forage made from partially dried grass, legumes, or a mixture of both. It is essentially a hybrid between hay and silage. The process involves wilting the crop to a lower moisture content than silage, typically between 40-60%, but higher than hay, which is usually below 20%. This intermediate moisture level is crucial for its preservation.

The wilting period allows for some aerobic respiration, which reduces the sugar content of the forage. After wilting, the material is tightly packed into bales or silos. The bales are then wrapped in plastic film, creating an anaerobic environment. This anaerobic condition is essential for the fermentation process to occur, similar to silage. Lactic acid bacteria, naturally present on the plant material, convert sugars into lactic acid and other organic acids. These acids lower the pH of the forage, inhibiting the growth of spoilage microorganisms like molds and yeasts.

Heulage offers advantages such as higher nutrient retention compared to hay, as it avoids the extensive drying and potential leaf loss associated with haymaking. It also generally has a lower risk of mold and dust compared to hay, making it a good option for animals with respiratory issues. However, proper wrapping and airtight storage are critical to prevent spoilage. If the plastic seal is broken, oxygen can enter, leading to mold growth and the production of undesirable fermentation byproducts, potentially making the heulage unpalatable or even harmful to livestock.