In today’s usage, silage is a type of animal feed formed when grass or other green crops of sufficiently high moisture content are fermented in anaerobic conditions in order to prevent spoilage by aerobic microorganisms. In fact, silage is sometimes casually referred to as “pickled pasture,” a fun term for fodder that’s been compacted, fermented, preserved, and fed to cattle, sheep, and other livestock during seasons where grazing is not optimal. Unlike hay, which is dried, baled, and stored in a manner that’s intended to protect it from any hint of moisture, silage is stored in a very damp state. The relatively higher moisture content of silage allows it to retain far more nutrients and energy than dried forage, making it a much more efficient food source.
Another important distinction between silage and hay is that, while animals don’t actually digest hay, silage is easily digested and offers greater nutritious value than dry alternatives. It’s true that ruminants, like cows and sheep, use their multi-chambered stomachs and specialized rumen bacteria to break down hay and many plant by-products that other animals can’t digest. Some other non-ruminants, like horses, are able to break down fibrous material like hay, soy hulls, beet pulp, and so on, essentially by allowing it to ferment in their hind gut. However, even in these cases, while animals can certainly thrive on a diet composed primarily of hay, silage generally provides more nutrition and energy, an important consideration when you’re looking for overall efficiency and cost-effectiveness.
Silage supplies energy, protein, and digestible fiber to livestock and it’s routinely fed on dairy and livestock farms around the world. Preserving forage through fermentation minimizes nutrient loss, allows feed to be mixed efficiently, on an as-needed basis in daily operations, and reduces the amount of wilting necessary at harvest. Unlike haymaking, ensiling is much less dependent on the weather and allows large volumes to be processed quickly.
Any green forage crop can be used for silage, and the best choice depends on your goals for your livestock, and which types grow well in your region. Corn and sorghum are well known high energy silage crops, while excellent low energy options include ordinary grasses, pearl millet, rye, vetches, and a variety of legumes such as alfalfa, red clover, and perennial peanut. When planting, In most cases, the best strategy for low-energy forage is to seed a number of ryegrass varieties (perennial, hybrid, or Italian) along with an alternative grass like timothy and white or red clover.
While it may be tempting, based on its name, to picture silage stored only in the scenic tower silos found on many farms, silage can be produced in anything from a simple hole in the ground, a series of constructed and lined bunkers to wrapped bales. Regardless of the complexity of the storage structure, the ultimate objective is to preserve organic material and prevent it from rotting, as would happen in a compost heap. Whichever fermentation and storage structure is used, there are two main phases in the ensiling process. The aerobic phase, when oxygen is initially present in the forage material, should be as brief as possible. The anaerobic phase is the longest phase and occurs when all oxygen has been consumed and a different set of bacteria launch the fermenting process. This means that perhaps the most important factor in producing and storing high quality silage is effective control of oxygen flow.
It’s probably not a surprise that different types of crops need to be managed differently during the ensiling process. High-energy crops, which are rich in simple sugars and starches, ferment rapidly and yield the greatest amount of energy per acre. Corn and sorghum are popular examples. Low-energy crops have comparatively lower levels of soluble carbohydrates, meaning they ferment more slowly and must be maintained at lower moisture levels to prevent spoilage. Regardless of which type of silage you’re making, there are well-established best practices and management techniques that will ensure your ensiling efforts produce consistently safe, high quality feed.
Because it offers a number of practical advantages over dry storage options, the use of silage is growing in popularity in the US, as well as across the world. The use of silage increases the potential yield of nutrients from available land, accommodates any type of forage crop, lowers overall feed costs, reduces harvest losses, and often increases forage quality. Compared to dry feed, crops destined for ensilage are less susceptible to damage from the vagaries of weather. The nature of silage also allows more use of mechanization during harvesting and feeding, potentially reducing labor costs.
