Research »   Storing Forages

Storing Forages

It is essential to harvest forage at the best time, from the point of view of nutritional quality, quantity available and climatic conditions, and then to store it properly to reduce losses. The objective of harvesting forage for storage is to preserve forage produced in the summer months in order to ensure winter feed for livestock when grazing is not feasible or accessible.


Hay uses desiccation or dry storage containing less than 15% water to prevent spoilage. Silage or wet storage uses the acidifying power of lactic bacteria, which reduces the pH to around 4, below which all chemical reaction and fermentation ceases. Haylage usually refers to a crop that is wilted to 60% moisture and is stored in oxygen limited structures or plastic bags. Limited haylage is produced in North America due to material handling problems, however it is very popular in Europe.

Hay baled at a high moisture content will spoil and mold. Silage must be firmly packed to minimize the oxygen content or it will spoil.

Silage can be successfully made from any green crop that has sufficient water-soluble carbohydrates and appropriate moisture content.1 In regions where frequent rain has a high risk of reducing hay quality, silage is a better option for storing forage nutrients. In regions that are dry and have challenges with targeting 68-70% moisture in silage after wilting due to high evapotranspiration, hay is preferred assuming the same forage is used with comparable quality and yield.

Advantages of Silage

  • Silage is harvested at relatively high moisture content and is wilted in the field for short periods of time, reducing field losses compared to hay production.
  • Preservative: During fermentation, the silage bacteria act on the cellulose and carbohydrates in the forage to produce volatile fatty acids (VFAs), such as acetic, propioniclactic, and butyric acids. By lowering pH, these create a hostile environment for competing bacteria that might cause spoilage. The VFAs thus act as natural preservative, during winter in temperate regions, when green forage is unavailable. The fermentation process that produces VFA also yields energy that the bacteria use: some of the energy is released as heat. Silage is thus modestly lower in caloric content than the original forage. However, this loss of energy is offset by the preservation characteristics and improved digestibility of silage.
  • Palatability: When silage is prepared under optimal conditions, the modest acidity also has the effect of improving palatability and provides a dietary contrast for the animal. It should be noted that excessive production of acetic and butyric acids can reduce palatability.
  • Several of the fermenting organisms produce vitamins (e.g. lactobacillus species produce folic acid and vitamin B12).
  • Consistency: Feedlot rations need to be consistent. Erratic ingredient quality can affect feed intake and animal performance. Alfalfa silage tends to be more consistent than alfalfa hay in cattle rations when wilted to 68-70% moisture, then packed properly2. However, the highly variable energy content of corn silage makes it challenging to maintain animal growth rate when cattle are fed high forage diets.

The choice of how forages are stored will depend on the region and climate but a producer must also consider that while silaging may have higher input costs, the per unit cost of production (COP) may be lower when taking into account that yield loss after wilting is only about 5% compared to hay, which can be 15-30% depending on weather. Further losses occur during storage, around 15% for silage and 20-35% for hay.3 Differences in feed quality must also be considered.

References

1. Crops for Silage production. Saskatchewan Ministry of Agriculture. http://www.agriculture.gov.sk.ca/Default.aspx?DN=cce79134-cefe-4e7c-a64e-08ea52f8ff99

2. Sprague, Dr. James I. September/October 1999. Alfalfa Silage vs. Alfalfa Hay. Feedlot VII (5) http://feedlotmagazine.com/archive/archive/issues/199909/alfalfa_pg52.html

3. Switch to hay could be a false economy. April 2011. Farmers Guardian. http://www.farmersguardian.com/home/livestock/profit-from-grass/switch-to-hay-could-be-a-false-economy/38277.article

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This topic was last revised on June 3, 2015 at 07:06 AM.

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