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Forage Crops

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As populations tended to concentrate and the need for winter feeding in northern climates grew, the need to harvest, cure and feed hay to domestic animals emerged. Although pasture dates to the earliest domestication of animals, the first cultivated forage plant may have been alfalfa, with its recorded use dating back to 490 BC in Persia and Greece.

Livestock forage is a crucial input for livestock rearing. Forages are grown for their vegetation and not their grains or seeds. Stems, leaves and inflorescences (flower clusters) of some legumes (e.g., alfalfa and clover) and a variety of non-legume grasses are used for grazing or harvested and fed to livestock. When grain crops such as corn, sorghum or straw are harvested for their vegetation, they are considered forage crops.

Production Processes

The major categories of forage crops are pastures and open ranges, hay and silage. Forage crops can be harvested by livestock (in pastures) or by humans, either by hand or machinery. The crop can be used for farm feeding or for sale. In forage production, tractors are a source of traction and processing power, and, in dry areas, irrigation may be required.

Pasture is fed by allowing the livestock to graze or browse. The type of pasture crop, typically grass, varies in its production with the season of the year, and pastures are managed for spring, summer and fall grazing. Range management focuses on not overgrazing an area, which involves rotating livestock from one area to another. Crop residues may be part of the pasture diet for livestock.

Alfalfa, a popular hay crop, is not a good pasture crop because it causes bloating in ruminants, a condition of a gas build-up in the rumen (the first part of the cow’s stomach) that can kill a cow. In temperate climates, pastures are ineffective as a feed source in the winter, so stored feed is needed. Moreover, in large operations, harvested forage—hay and silage—is used because pasture is impractical for large concentrations of animals.

Hay is forage that is grown and dry-cured before storage and feeding. After the hay crop has grown, it is cut with a mowing machine or swather (a machine that combines the mowing and raking operations) and raked by a machine into a long row for drying (a windrow). During these two processes it is field cured for baling. Historically harvesting was done by pitchforking loose hay, which may still be used to feed the animals. Once cured, the hay is baled. The baling machine picks up the hay from the windrow, and compresses and wraps it into either a small square bale for manual handling, or large square or round bales for mechanical handling. The small bale may be kicked mechanically from the baler back into a trailer, or it may be picked up by hand and placed—a task called bucking—onto a trailer for transport to the storage area. The bales are stored in stacks, usually under a cover (barn, shed or plastic) to protect them from rain. Wet hay can easily spoil or spontaneously combust from the heat of the decaying process. Hay may be processed for commercial use into compressed pellets or cubes. A crop can be cut several times in a season, three times being typical. When it is fed, a bale is moved to the feeding trough, opened and placed into the trough where the animal can reach it. This part of the operation is typically manual.

Other forage that is harvested for livestock feeding is corn or sorghum for silage. The economic advantage is that corn has as much as 50% more energy when harvested as silage than grain. A machine is used to harvest most of the green plant. The crop is cut, crushed, chopped and ejected into a trailer. The material is then fed as green chop or stored in a silo, where it undergoes fermentation in the first 2 weeks. The fermentation establishes an environment that prevents spoilage. Over a year, the silo is emptied as the silage is fed to livestock. This feeding process is primarily mechanical.

Hazards and Their Prevention

The storage of animal feed presents health hazards for workers. Early in the storage process, nitrogen dioxide is produced and can cause serious respiratory damage and death (“silo filler’s disease”). Storage in enclosed environments, such as silos, can create this hazard, which can be avoided by not entering silos or enclosed storage spaces in the first few weeks after feed has been stored. Further problems can occur later if the alfalfa, hay, straw or other forage crop was wet when it was stored and there is a build-up of fungi and other microbial contaminants. This can result in acute respiratory illness (“silo unloader’s disease”, organic dust toxicity) and/or chronic respiratory diseases (“farmer’s lung”). The risk of acute and chronic respiratory diseases can be reduced through the use of appropriate respirators. There should also be appropriate confined space entry procedures.

The straw and hay used for bedding is usually dry and old, but may contain moulds and spores which can cause respiratory symptoms when dust is made airborne. Dust respirators can reduce exposure to this hazard.

Harvesting and baling equipment and bedding choppers are designed to chop, cut and mangle. They have been associated with traumatic injuries to farm workers. Many of these injuries occur when workers try to clear clogged parts while the equipment is still operating. The equipment should be turned off before clearing jams. If more than one person is working, then a lockout/tagout programme should be in effect. Another major source of injuries and fatalities is tractor overturns without proper roll-over protection for the driver (Deere & Co. 1994). More information on farm machinery hazards is also discussed elsewhere in this Encyclopaedia.

Where animals are used to plant, harvest and store feed, there is a possibility of animal-related injuries from kicks, bites, strains, sprains, crush injuries and lacerations. Correct animal handling techniques are the most likely means to reduce these injuries.

Manual handling of bales of hay and straw can result in ergonomic problems. Workers should be trained in correct lifting procedures, and mechanical equipment should be used where possible.

Forage and bedding are fire hazards. Wet hay, as mentioned previously, is a spontaneous combustion hazard. Dry hay, straw and so forth will burn easily, especially when loose. Even bailed forage is a major fuel source in a fire. Basic fire precautions should be instituted, such as no-smoking rules, elimination of spark sources and fire suppression measures.



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