The term ‘food’ is usually used in relation to human diets while the term ‘feed’ is used in relation to farm animals. However, foods and foodstuffs are sometimes used for both farm animals and human beings to describe foods and feed ingredients that are sources of nutrients in the diet.
The term feeds include all such material which can be used for feeding of livestock. There are various types of feed stuffs available for livestock feeding. These feed stuffs can be grouped into different classes based on bulkiness and chemical composition.
No two feeding stuffs are alike in the composition and characteristic but in practical feeding, substitution of one feeding stuff is made with another depending upon the market price and availability in a particular region.
Therefore, it is necessary to know the categories of the feeds within which substitutions are justified for the feeds having similar nutritional properties. Feeds of many origins, qualities, and availabilities are used in animal diets and nutritive content varies tremendously among them.
The National Research Council groups feedstuffs with others with similar characteristics. Feedstuffs within a group generally have similar nutritive values. Most feeds fall into these categories:
Classification of Feeding stuffs
Dry forages and roughages;
Pasture, range plants and green forages;
Silages;
Energy feeds;
Protein supplements;
Mineral supplements;
Vitamin supplements;
Non-nutritive/feed additives.
Now in this article, we shall consider dry forages and roughages.
Dry Forages and Roughages
Forage is a plant material (mainly plant leaves and stems) other than separated grain, produced to be grazed or harvested for use as feed for animals.
While the term forage has a broad definition, the term forage crop is used to define crops, annual or biennial, which are grown to be utilized by grazing or harvesting as a whole crop.
The term forage could also be defined as herbaceous plants or plant parts fed to domestic animals. On the farm, roughage is normally considered to be material making up fodder such as hay, silage; pastures, etc.
The distinguishing characteristic of roughage is usually a high fiber content. Roughages are plant based feedstuff with a high fiber content forages. Sometimes roughages and forages are used interchangeable. Roughages comprise over 50% of all feedstuffs fed to livestock animals.
Characteristics of Dry Forages and Roughages
Dry forages and roughages are high in cellulose, hemicellulose, and possibly lignin.
Are low in readily digested carbohydrates such as starch and sugars.
Fibrous carbohydrates are associated with the structural components of plants.
Roughages may also contain relatively high amounts of lignin. Lignin content increases with plant maturity.
In a nutrition analysis, the fiber components of roughages may be expressed as crude fiber, acid detergent fiber (ADF), and/or neutral detergent fiber (NDF). Crude fiber contains cellulose and a portion of the lignin.
ADF contains cellulose and lignin. Neutral detergent fiber (NDF) contains hemicellulose, cellulose, and lignin.
The nonfibrous carbohydrate content is comprised of simple sugars (i.e. fructose, glucose, and sucrose), starches, and/or fructosans.
Generally, the digestible energy contents of roughages are low. Feeds placed in this category contain at least 18% crude fiber, with values ranging up to 50% crude fiber.
The protein component in forages comprise of both true protein and nonprotein nitrogen compounds.
Protein content varies from nearly 30% for alfalfa to 2-3% for some straws for example young, well-fertilized wheat pasture can have high crude protein and be very digestible while late season prairie hay is the opposite.
As a rule of thumb, legumes and grasses have about the same energy content, but legumes have much higher protein, calcium, and carotene contents.
Grasses, even when dormant, are fair to good sources of energy for ruminant animals, but other nutrients, especially crude protein and carotene, are likely deficient when plants are dormant. New foliage is always more digestible than more mature foliage.
Legumes have a higher calcium and magnesium contents compared to grasses. Roughages are also a good source of the B-complex vitamins and fat-soluble vitamins.
Roughages may contain one or more anti-nutritional factors such as alkaloids, cyanogenic glycosides, toxic amino acids, and/or mycotoxins.
The moisture content is usually between 50-85% but can be quite variable. A forage is generally considered to be of higher quality than a roughage.
It is common to divide forages and roughages into legumes (e.g., alfalfa, lespedeza, soybeans, and clovers) and grasses (e.g., prairie grasses, timothy, Bermuda grass, and wheat). Grasses are plants with jointed stems.
The stems are normally hollow between the joints (node). Leaves are in two rows on the stem. Veins in the leaves are parallel. About 75% of forage consumed in the tropics is grass.
Legumes are generally better quality feed than grasses because the former has a lower stem and higher leaf content. The mineral content of roughages is influenced by roughage and mineral content of the soil.
Generally, roughages are higher in calcium, potassium, and micro-minerals and moderate to low in phosphorus when compared to concentrates.
In addition to grasses and legumes many other kinds of plants are at times valuable. Although seldom cultivated, they may be parts of the unimproved pasture and be convenient to use under some circumstances.
Miscellaneous Group of Roughages and Forages
This group includes annual herbs (forbs) and woody shrubs and trees (browse).
Forbs are broad-leaved plants with aboveground growth that dies back each year. Most forbs have net veins in the leaves, but a few have parallel veins. Broadleaf weeds and wild flowers are examples of forbs.
Grass-like plants look like grasses but have solid, though not hollow, stems without joints. Stems may be triangular. Veins in the leaves are parallel for example sedges and rushes.
Browse Leaf and twig growth of shrubs, woody vines, trees, cacti, and other non-herbaceous vegetation available for animal consumption. Trees and shrubs are plants with persistent woody stems that live from one year to the next.
Shrubs have stems that branch from near the base, while trees have a definite trunk and are usually bigger than shrubs. Some plants can take on a shrub or tree growth form, depending on environmental conditions.
The season of scarcity in the tropics is governed by rainfall, not temperature; the length of the dry season varies with latitude and site, from a few months to over half the year, but even when there is adequate moisture late in the season, especially in high-rainfall areas, the mature herbage may be almost worthless as animal feed and only selective grazing, and fire to “freshen” the grass, may assure survival of the stock.
Hay made from natural grassland in the tropics is, unfortunately, much less likely to give satisfactory results than that from other zones; bush hay is usually made late in the rains because of the difficulty of drying at other times and is no better than straw or stover.
This, along with a relatively low stock density in the past, may be why there is little if any tradition of haymaking in the humid and sub- humid tropics.
Hay from sown crops can be made on mechanized farms under tropical conditions, but its quality will be governed by the genetic limits of tropical grasses, except at high altitudes, where exotics can be grown.
Discussing herbage quality from tropical pastures – at all stages, not just over- mature – Butterworth (1967; 1985) indicates that the crude protein content of 235 samples was 7.5% ±3.5%, with 235 under 7% (7% is the level for zero liveweight gain.).
Crude protein content decreases with maturity as the cell contents are diluted by structural components. As the crude protein content decreases, so does its digestibility.
Of 473 samples, 58% were below the needs for growth of beef cattle. The average total digestible nutrients (TDN) of 312 samples was 54.0 ±7.9%, with 43.5% below the 55% level recommended by the Agricultural Research Council (ARC) for grazing cattle; in tropical pastures, TDN is less likely to be limiting than is crude protein.
Vegetation Terms/Definitions
Forage: Edible parts of plants, other than separated grain, that can provide feed for grazing animals, or that can be harvested for feeding. Includes browse, herbage, and mast. Forage could be
Carbonaceous (low protein) – Fresh Grama grass, fresh Wheatgrass etc.
Proteinaceous (high protein) – Fresh & early vegetative Wheatgrass, etc. Grazed parts (growing & dormant), greenchop, food crop residues, etc.
Herbage: The biomass of herbaceous plants, other than separated grain, generally above ground but including edible roots and tubers.
Forb: Any herbaceous broadleaf plant that is not a grass and is not grass- like.
Legume: Members of the plant family Fabaceae.
Grass: Members of the plant family Poaceae.
Grass-likeplants: are plants similar to grass in appearance and is usually a member of the plant family Cyperaceae (sedges) or Juncaceae (rushes).
Mast: Fruits and seeds of shrubs, woody vines, trees, cacti, and other non- herbaceous vegetation available for animal consumption.
Read Also : Uses and Importance of Fats, Vitamins, Minerals and Water in Animal Feeds
Meaning of Pasture
Pasture is a field or land planted with grass or similar plants suitable for animals to eat. Pasture it could also be defined as an area enclosed for growing forage and allowing animals, such as cattle, sheep, or goats, to graze.
Pastures can support a wide range of plant species, offering varying degrees of nutrition for the grazers, stability for the pasture in terms of soil health, and habitat for wildlife.
Meaning of Range Plants
The EPA defines rangelands as “those lands on which the native vegetation (climax or natural potential plant community) is predominantly grasses, grass-like plants, forbs, or shrubs suitable for grazing or browsing use.
Rangelands include natural grassland, savannas, many wetlands, some deserts, tundra, and certain forb and shrub communities.
Rangeland is less intensively managed than pastures, typically supports more native species, can be open (not enclosed by fencing) and can be grazed by wildlife or livestock
Meaning of Fodder
Fodder is a type of animal feed, it is any agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, rabbits, sheep, horses, chickens and pigs.
“Fodder” refers particularly to food given to the animals (including plants cut and carried to them), rather than that which they forage for themselves (called forage).
Fodder can be also called provender and includes hay, straw, silage, compressed and pelleted feeds, oils and mixed rations, and sprouted grains and legumes (such as bean sprouts, fresh malt, or spent malt).
In many cases the production of grass for cattle fodder is a valuable intercrop between crops for human consumption, because it builds the organic matter in the soil.
Function of Roughages
Feeds in these categories provide the bulk of the diets of herbivorous species (ruminants and cecal fermenters).
Roughages also function to maintain and optimize the efficiency of the GI tract for selected species.
For selected species, fibrous carbohydrates function to maintain structure, activity, and microbial population of the GI tract, essential for optimal function of the GI tract.
Roughages are a link to the efficient utilization of earth‘s resources.
Roughages alone are of minimal value to humans. However, roughages consumed by selected species provide a means for conversion of relatively low-quality raw materials to relatively high-quality products such as food and fiber that may be used to fulfill human needs.
Types of Roughages
Roughages may be fed either in a fresh, dried, or ensiled state.
Grazed roughages (e.g. pasture and range),
Preserved roughages (e.g. hay and silage);
Crop residues and by-products (e.g. groundnut husk, maize cob, cowpea haulms and cowpea husk) and hulls.
Roughages are further classified into two major group as:
Green / succulent roughages – They contain about 60-90 percent moisture examples are pastures, cultivated fodders, tree leaves, root crops and silages.
Dry roughages – They contain about 10-15 percent moisture e.g. Straw, Hay and kadbi.
Factors Affecting Utilization of Roughages
In addition to other factors such as plant species, the nutritional value of roughages depends on the proportion of cell contents to cell wall components and on the extent of cell wall lignification.
Most roughages can be effectively incorporated into at least one type of ration. Effective use of a roughage requires matching nutrient requirements of an animal with the nutritional value of a roughage.
Effective use of a roughage also requires appropriate processing and supplementation.
As stated earlier, in ruminants, enzymes from rumen microorganisms are required for the digestion of roughages.
As the population of rumen microorganisms is dep3.7endent upon the feedstuffs consumed, the composition of the diet influences the extent and rate of digestion of roughages.
Feeding of high-energy feedstuffs has a negative associative effect on the degree of utilization of a roughage. As with other feedstuffs, addition of roughages to rations is dependent on the GI tract.
As roughages are high in fibrous carbohydrates and microbial enzymes are required for digestion of fibrous carbohydrates, utilization efficiency of roughages is dependent on the site and extent of microbial fermentation in the GI tract.
Roughages are primarily added to the rations of herbivores. For monogastric animals such as swine and poultry, the low utilization efficiency limits the use of roughages in rations. Roughages can be added to the ration of swine with low nutrient requirements.
Characteristics of Good-Quality Forage
Being relatively immature when harvested;
Being green and leafy;
Having soft, pliable stems;
Being free from molds or mustiness;
Being palatable; and being free from foreign material.
Factors Affecting the Nutritive Content of Forages and Roughages
Maturity at the time of harvesting,
Weather damage,
Soil fertility,
Plant species, and harvesting method.
Maturity at the time of harvesting is perhaps the most important factor because all nutrients, except fiber (which increases), decrease with maturity. The digestibility and palatability of a forage decreases with advancing maturity and increasing fiber level.
The rate of change is much greater for some plants than for others. The effects of maturity are more pronounced for grasses than for legumes.
Examples of dry forages and roughages include; legume hay, grass hays, wheat straw, cornstalks, corncobs, cottonseed hulls, peanut hulls, and rice hulls.
Pasture, range plants, and green forages Bermuda grass pasture, sorghum-sudan grass, tall-grass prairie species, wheat pasture.
Other feeds, such as sugar beet pulp, brewers‘ grains, and pineapple bran, are by- products that remain after a food crop has been processed for human use. Surplus food crops, such as wheat, other cereals, fruits, vegetables, and roots, may also be fed to animals.
Meaning of Silages
Silage refers to the feed preserved by an anaerobic fermentation process (e.g., corn silage, haylage, high moisture corn) in which lactic acid and volatile fatty acids (produced by fermentation) lower the pH of the silage.
The low pH preserves the silage by killing off bacteria, molds, and other destructive organisms. One common misconception is that ensiling improves the nutritive content of a feed. Fermentation uses nutrients and thus reduces nutritive content of the material.
Silage additives refer to the substances added during the ensiling process to enhance production of lactic acid and/or a rapid decrease in pH of the feed.
The nutritive value of grass silage depends upon the composition of the original material and the losses incurred during the process of ensiling. Such losses occur from initial respiration, fermentation and seepage at the top and sides of the silo.
All of these losses may be considerable unless the silage is well made. For a well- made grass silage, the loss of original dry matter and TDN (total digestible nutrients) is approximately 25%. A poor-quality silage frequently results from under-consolidation.
This occurs when the ensiled material consists of very young, wet, high protein grass which has a low content of fermentable carbohydrate. When the silage mass is under-consolidated, over-heating occurs which leads to excessive destruction of carbohydrates and a marked reduction in the digestibility of the proteins.
Hence, over-heated silages have a low nutritive value, but are very palatable. The other type of poor-quality silage also made from young high- moisture grass occurs when the fermentation and acidification rate is very slow.
This happens when there is not enough fermentable carbohydrate in the ensiled material. Butyric acid-forming organisms increase rapidly, very little heat is produced and considerable breaking down of proteins to ammonia occurs.
The result is very unpalatable silage with an unpleasant smell, and a lowered feed value because of protein losses.
In summary, in this article we have seen that forages and roughages provide inexpensive feed ingredients for animals and available.
The nutritional value, function and types of roughages and forages have been explained.
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