Harvesting forage for storage is only possible in meadowlands sufficiently well-maintained for this purpose or by growing intensive annual forage crops. It presupposes land prepared specifically for this use, even if it alternates with grazing. Cutting helps maintain permanent meadowland. On the other hand, intensive cropping poses the same environmental problems as agriculture.
The objective is to preserve forage resources for the dry season (hot countries) or for winter (temperate countries) in order to ensure continuous regular feed for livestock, either to sustain growth, fattening or milk production, or to continue production in difficult periods when market prices are highest.
a Chadian village (N ’Djamena region).
(click on photo to enlarge)
Preparation of green forage (containing between 65 and 80 % water) for storage relies on three different techniques:
Dessication or dry storage: the product obtained is hay, containing less than 15 % water. Silage-making or wet storage: the product obtained is silage. This method of storage uses the acidifying power of lactic bacteria, which reduces the pH to around 4, below which all chemical reaction and fermentation ceases.
During tedding, green forage is cut and dried as quickly as possible. Drying can be done naturally (exposure to the sun on the ground aerating the forage regularly by turning it over) or artificially by active circulation of air. Sun-drying requires 2 or 3 days without rain. The hay must then be kept in appropriate conditions (covered area). If, when harvesting, the grass has matured and has already dried standing, it is not hay but straw.
Silage-making is a fermentation process aimed at preserving forage in its wet state away from air. One is seeking to lose minimum dry matter and nutritional value and to avoid creating products toxic to the animal. To obtain good silage, it is necessary to:
Hay produced on grazing land (Sahel) has the nutritive value of straw because it is harvested when the plants reach maturity. The product obtained only permits basic maintenance needs and in rare cases marginal production of milk and meat.
Round Bale Silage
Round bale silage is a relatively new method of preserving forage. It is a combination of hay and silage making and has certain advantages and disadvantages over other forage preservation systems. Round bale silage is simply forage of a relatively high moisture content that is baled with a round baler and then stored in a sealed container, usually a plastic bag. Both grasses and legumes can be preserved as round bale silage if proper techniques are followed. It is much easier to make good hay crop silage in silos than in large round bales.
Although the silage obtained can be kept for approximately a year, baled silage is more likely to spoil compared to silage in traditional silos because (1) fermentation is less complete and (2) damage to the plastic covering results in harmful introduction of oxygen. Some people think that baled silage is best adapted for use late in the growing season, with bales fed as early as possible Late in the season may often be a difficult time to dry hay in the field - increasing the value of round bale silage.
The feeding value of round bale silage will be no better than the quality of the starting forage, and usually it is worse. If bales are moldy and warm when opened feeding value will be poor. Moldy forage reduces feed intake which reduces production. Warm or hot forages have reduced protein digestibility which must be accounted for when balancing diets. It is a good idea to analyze round bale silage for normal components such as protein, fibre and minerals and also for available protein prior to feeding. Severely spoiled bales also can contain harmful bacteria (e.g. Listeria) and molds and should not be fed.
Round bale silage has three distinct advantages over haymaking or conventional silage making:
These include cost of cutting and collecting, making the product (tedding, making the silage), consumables (energy, inputs), depreciation of equipment, depreciation of buildings (grain store, silo), and labor, often abundant for these operations. Preserved forage is therefore expensive.
For hay to be profitable, it is essential to:
Many different losses of nutrients can occur between cutting a forage crop and harvesting the crop. Respiration is unavoidable and largely independent of the type of harvesting system used. Other losses such as mechanical shattering and rain damage can be avoided or greatly reduced depending upon how the forage is harvested. Haymaking generally causes the greatest field losses because forage is dry when it is mechanically handled. Estimates of dry matter losses when forage is baled with large round balers range from 5 to 20% of the crop. Losses caused by small square balers generally range from 5-10%. The amount of loss is directly proportional to the dry matter content of the forage when handled. Forage containing more than 40% moisture resist echanical shattering (average loss is about 3%), but as forages become drier than 40% moisture, shatter losses increase rapidly. nother potential loss during haymaking is rain damage. The longer a forage crop lays in the field the greater the risk of rain. Silage (round bale or conventional) usually has to wilt about one day prior to harvest; therefore, the risk of rain is less than for haymaking. Round bale silage is similar to conventional silage making with less risk of rain damage and decreased nutrient losses due to mechanical shattering as compared to haymaking.
Conventional silage-making reduces field losses as compared to haymaking, but has large capital costs. Conventional silage making requires a forage chopper, silage wagons, silage blower, a silo, and unloader plus forage cutting equipment. Haymaking requires the same forage cutting equipment plus a baler, some hay wagons, and a storage barn. Capital costs for conventional silage making range from 2 to 3 times more than haymaking. Round bale silage making requires less capital cost than haymaking because a hay barn is not required. If bales are wrapped instead of bagged a bale wrapper is needed that will increase capital outlay.
Round bale silage is a very flexible system because of its low capital costs. Depending upon weather and labor factors, a producer can choose to either make large round bale hay or round bale silage. If a producer owns conventional silage making equipment, the high capital investment in equipment almost mandates that forage be stored as silage. With round bale silage, a major portion of the cost is in bags or wrapping. Therefore, if a producer chooses not to make round bale silage, he simply does not purchase any bags or plastic wrapping. His haymaking equipment, however, is still productive.
Round bale silage is a flexible, low capital cost method of preserving
forage; however, variable costs and spoilage losses can be high. This system
of storing forage might be most practical for smaller farms that can not
justify the high investment needed for conventional silage storage. Also,
it may be appropriate for occasional use by forage producers, preferably
late in the growing season. If proper techniques are followed, acceptable
quality silage can be produced. Higher storage costs and proper disposal
of used plastic must be considered when making the decision to use round
Targeted Livestock Systems
Grazing systems in conditions of intensified farming, also in mixed systems. Sometimes in extensive grazing systems.
Context of Application
Hay-making is the most important method of preserving forage in many countries, including tropical ones. Silage-making is highly developed in temperate countries, especially in Europe, and goes with intensification.
In tropical countries, plant growth coincides with the rainy season, which sometimes makes hay-making difficult. Production of silage requires suitable, expensive equipment, and uses forage which is very productive and of very high quality. This technique has come to the fore since farms have acquired powerful equipment to fill the silo quickly and since high-yield forage plants (maize, sorghum) have become available.
Demarquilly C., 1987. Les fourrages secs. Récolte, traitement, utilisation. INRA, Paris.
IEMVT-CIRAD, 1992 and 1994. Les réserves fourragères. 1. Le foin, 2. Les pailles et leur valorisation, 3. L'ensilage. Les fiches techniques d'élevage tropical . Ministère français de la coopération et du développement. 12, pp. 8 et 8.
Dairy On-Line http://www.dairyonline.com/default.htm
[Livestock & Environment Toolbox Home]