The difference between hay and silage
Hay and silage are both forms of preserved forage used to feed livestock, but they are produced and stored in different ways, resulting in different characteristics.
**Hay**:
- Made by cutting and drying grasses or legumes until they have a moisture content of around 15-20%.
- Drying typically occurs in the field, with the forage being turned periodically to ensure even drying.
- The low moisture content prevents microbial activity, which preserves the forage.
- Once dry, hay is usually baled into small square bales, large round bales or large rectangular bales for storage and transport.
- It is susceptible to mold and spoilage if it gets wet or isn't dried properly.
- Hay generally has a lower nutritive value than silage, as some nutrients are lost during the drying process.
- Hay is used to provide the fiber component in the diets of animals and is typically fed in situations where animals have plenty of space to graze and move around.
**Silage**:
- Produced by fermenting high-moisture forage (anywhere from 40% to 70% moisture) in an anaerobic (oxygen-free) environment.
- The forage is chopped into small pieces and then compacted in a storage unit such as a silo, silage bag, or wrapped in plastic as a silage bale to exclude air.
- The high moisture and lack of oxygen encourage the growth of lactic acid bacteria, which ferment the sugars in the plant material to produce lactic acid. This acid lowers the pH and stabilizes the forage, preventing spoilage and retaining more of its nutrients.
- Silage can be made from a range of forage crops, including grass, corn (maize), sorghum, and other cereals.
- Properly made silage has a characteristic acidic smell and is often more palatable and digestible for livestock, leading to increased feed efficiency.
- It must be carefully managed to avoid contamination with air that could spoil the batch and to ensure that the pH is low enough to prevent the growth of undesirable microorganisms.
In summary, the key difference between hay and silage is the moisture content at the time of storage and the method used to preserve the forage. Hay is dried and baled, while silage is compacted and fermented in a moist, anaerobic environment.