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close this book Animal traction
close this folder Appendix B: Animal nutrition
View the document Energy needs: bovine animals
View the document Energy needs: equine animals
View the document Nutrient needs of draft animals: protein, minerals, vitamins
View the document Feeds and feed composition
View the document Calculating a ration
View the document Recommended rations and feeding practices

Feeds and feed composition

The feed given to draft animals is called forage. Forage sometimes refers to the leafy, fibrous, or tuberous portion of plants consumed by animals, but it may also refer to any edible portion of the plant. Forage may be wild or domestic, fresh or dry, standing (as in the field or forest) or harvested and stored. When green forage is fermented in a pit or silo, it is called silage.

It is important to distinguish the various types of forage materials, know their basic nutritive properties, and understand how they are analyzed before using feed composition tables. (Feed Composition Tables)

Forages are divided into roughages and concentrates. Roughages include green pasture (pasture grass), hays, legumes, and fadders. They are classified together because of the fiber content. When a feed analysis is made on roughages, all of the moisture is removed and composition is given on a "100% dry matter basis". That is, only the plant solids are analyzed.

Concentrates include low fiber, highly digestible feeds like grain, grain by-products, and high protein meals. They are analyzed on an "asfed basis", which means the feed is analyzed as it is normally fed to the animal.

Pasture

Pasture refers to any grass or legumes, usually green, which are fed to animals. Pasture may also refer to the land area where the plants grow and where the animals graze. Pasture is highest in nutritional value when it is young and succulent (high in moisture).

Green Chop or Soiling Crop

Normally, work animals are allowed to graze. At times, however, plants are cut and brought to

them. Cut pasture is called green chop or soiling crop. The rainy season work schedule may limit daytime grazing and the farmer may want to feed fresh-cut pasture in the stable or paddock area rather than send animals out at night.

A maturing pasture loses moisture. Feed composition tables reflect water loss by the increasing percentage of dry matter and decreasing amounts of digestible protein, minerals, and digestible energy (forage value). Most grasses with a dry matter content between 20 and 30% have greater than maintenance nutrient content. Grass with a dry matter range of 20-40% is sometimes classified as "standing hay".

Hay

Hay is any grass or legume which is cut (or mown), dried, and preserved as a winter or dry season forage. The dry matter content of hay ranges from 40-85%. Hay has a high nutrient quality when it is cut before it goes to seed. Cut grass is allowed to dry, or "cure," in the field. Because the grass contains moisture, it must be turned to expose the underside to sunlight; otherwise, it will mold. The hay is cured when it snaps without releasing juice or moisture (this usually takes 1-3 days in the tropics). Hay is stored in an enclosed compartment (an old house or hut is suitable if not termite infested) where light and wind cannot enter and cause further drying. In the humid tropics where molding is highly likely, air circulation (wind) is an advantage, and storage should allow for this. If late season rains make it difficult to cure hay, grass can be preserved by making it into silage (see below).

Good quality hay is green in color, slightly brittle, has a clean, fragrant smell, and is free of dirt, stones, and woody stems. If hay is offered from a rack or trough, it does not pick up dust; dusty hay should be sprinkled with water before it is fed to keep animals from developing heaves (coughing condition) which can lead to pneumonia.

Most kinds of grass hay (except legume hay) of the same quality or grade have about equal nutritional value. The definition of "hay" varies. Some tables, especially those based on arid area

Roughage

% dry matter

% digestible protein*

digestible energy (U.F.)

Green pasture

under 20

over 6

over 0.6

Standing hay

20-40

2-5

0.5-0.6

Cured hay

40-85

1-5

0.4-0.5

Grass straw

85

under 1

under 0.4

*Values based on 100% dry matter.

Straw

Straw is dead or dying grass. It contains very little moisture, is high in coarse fiber and low in nutritional value. Bovine animals, because of unique digestive abilities, are able to derive more nutrients from the fibers than horses or donkeys. Straw is especially useful when animals are kept on lowenergy diets (during the off season); then it should be fed with protein and mineral supplements. Straw contains few vitamins; these are supplied in the high quality hays and silages which should comprise the greater part of the roughage diet.

Legumes

Legumes include nitrogenfixing plants like clover, alfalfa or beans which are much higher in protein, calcium, and Vitamin A and D content than grasses. Legumes can be offered fresh, as silage or as hay. Their ability to "fix" or put nitrogen into the soil makes them an important part of crop rotation schemes. Planted in association with grass crops, legumes improve both the soil and the crop, adding fertilizer (nitrogen) to the pasture mix. The leaves (and stems) of cowpeas, soybeans and peanuts can be dried as hay or wilted and preserved as silage after the seed is harvested. These feeds, when mixed with drier, coarser forages, improve the nutritional value of the ration, and also have a mild laxative effect that helps the animal eliminate the indigestible fibers. However, fast-growing lush young legumes in the pre-flowering stages may cause bloat or colic when offered to cattle or equine animals, and therefore should be avoided or restricted.

Fodder

Fodder is the combination of leaves, stems, husks, hulls (peanut shells), cobs, or grain which is chopped, mixed, and usually fed in a dry state. Corn (or sorghum) grown specifically for animal feed and cut before the grain matures is called corn fodder. Corn fodder may be cured, ensiled, or fed fresh. Shock corn is similar to fodder but the grain has been allowed to mature before the plant is cut and chopped. Corn stover is a mixture made of dried stalks, leaves, and husks; the ear (cob and grain) has been removed. Tree fodder is a term applied to the leafy tree branches which graziers (herders) cut for their animals. In Africa, many species of Acacia are used as tree fodder. The leaves and stems are green during the dry season; they are high in calcium and phosphorous.

Grain

Grain is the seed portion of cereal plants-corn, sorghum, millet, and rice. Grains are low in the bulky fibers that constitute the plants which produce them; as a result, they are classified as "concentrates". They are high in starch value (carbohydrates) and therefore an important source of energy to work animals that have limited time to graze. They are not low in protein, but the proteins found in grain are not as easily digested as those found in legumes. Animals not accustomed to eating grain may find it unpalatable; in these cases the grain should be partially crushed and a small quantity of salt or brewers' wet meal added (see below). The feeding of shock corn or fodder/grain mixes is an effective means of introducing grain into the diets of animals raised on pasture. Some tests made in West Africa approximate the total nutritional value of grains as compared to quantities of mixed natural pasture:

1 kg of crushed millet = 7 kg of pasture

1 kg of crushed corn = 9 kg of pasture

1 kg of cotton seed = 6 kg of pasture.

Some grains have a U.F. value greater than one (1) because of high fat content. Fat has 2.25 times more energy per unit than carbohydrates.

Overfeeding of grains results in serious digestive problems. Generally speaking, an animal should not be fed more than 2 kg of grain per day. Horses may "bolt" grain by swallowing it whole or only partially chewed. This can be prevented by mixing grasses or legumes in with the grain or by placing several large, round stones in the feed.

Grain By-products

These include the hulls, brans, polishings and germs (centers) of the grain kernel. They are separated from the meaty, starchy portion of the kernel during the milling process. The hull is the hard, outer shell of the seed. Softer layers called bran may be found between the hull and the meat, or in the outermost coating (wheat has no hull but rather bran layers). Polishings are powdery residues that are separated from the finer flour when rice grain is milled. Brewers' wet meal is the residue of sprouted millet, corn or sorghum which is boiled to make beer. In Africa brewers' meal is sometimes mixed with water and offered as a mash to horses. Grain by-products (except for hulls) are generally high in fiber, protein and minerals and are less expensive to feed than whole kernels.

Seeds and Seed Cake

The seeds and seed cake of cotton plants (oil seed) and bean, pea, and peanut plants (legume seed) are high in energy and fat and may be fed whole or in a processed form. When the hulls (shells) of peanuts or cotton are removed and the oil extracted from the raw meat, the or cake. Sometimes the meal contains some hull material; it almost always contains some oil. Meal and cake have the same composition, but meal is loose and finely ground whereas cake consists of large chunks.

Silage

Silage is succulent forage material which has been cut, chopped and preserved in an air-tight compartment. It is a palatable, inexpensive feed which is higher in moisture and nutrient content than either hay or dry fodder. It is extremely useful in areas where seasonal dryness limits natural grazing. Green forage, preferably corn or sorghum fodder, young grass, and legumes are wilted in the field to a moisture level of 60-70X. This takes from 2 to 24 hours depending upon the humidity. The forage is dropped when stems can be twisted without breaking, but before leaves show any signs of dryness. The chopped plants then are layered and compacted in a 2mx2mx2m earth walled pit (or longer trench of equal depth, slightly pitched to allow for drainage). The pit is covered with earth and a natural fermentation process occurs. If the plant material has been tightly compressed without air pockets or leaks, no molding or rotting should occur. Hay, dry fodder, or partially-wilted legume tops (such as the leaves of the harvested peanut plant) also may be ensiled, but in drier regions, some water may have to be sprinkled in with the forage as it is trampled down to ensure that fermentation occurs. (For further information on silage, see ICE Reprint No. lie, Utilization and Construction of Pit Silos.)