Classification of Feeding Stuff and Feed Supplements: Cereals

Cereals play an important role in world agriculture. They contribute significantly to the global food pool in achieving food and nutritional security. Cereals that are mostly used in the tropical countries are maize, rice and guinea corn and to a less extent millet and wheat.

In temperate climate, wheat, barley, oat and rye may be available for use in the diets of farm animals and human beings. Cereals are high in starches that are readily digested by animals.

They are relatively low in protein content and in general are of poor quality because of the lack of balance in amino acid composition. Cereal energy constitutes below 45 – 70% of the energy in poultry, swine and rabbit diets.

Cereals contain fair amount of calcium, phosphorus and iron, although the absorption of these minerals vary. Whole cereals contain useful amounts of B vitamins although most of these B vitamins are lost in the milling process to which the grains are subjected in the preparation of various foods from them.

They are however totally devoid of vitamin B12 and ascorbic acid. Vitamin A in cereals is low except for yellow maize, cereals are also deficient in the amino acid such as lysine and tryptophan.

Examples of Some Cereals and Their Nutritional Value

1. Maize (Zea mays)

It is grown extensively in the country for human food as well as livestock feed. It is used for all classes of livestock. Essentially maize supply energy which is as high as 14.2 MJ/kg. It is low in protein (8-10%) depending on the variety. Its protein content is low in lysine and tryptophan.

The fat content is about 4% and high in linoleic acid an essential fatty acid (about 50%). Yellow maize contains Xanthophyll which gives yellow colouration to the shank, skin, egg yolk of birds and carcass of pig fed diet containing yellow maize.

Yellow maize contains carotenoids which have pro vitamin A activity 100 – 800 mg/100g. White maize is low in xanthophylls and lacking in vitamin A activity.

Green leaves, palm oil or synthetic colourant can be added to white maize. Niacin in maize is in bound form and is not easily available.

However, treatment with home water makes the niacin more available. Maize is used up to 60% in livestock feed. It is sometimes difficult to do 100% replacement of maize.

2. Sorghum (Guinea corn)

It is widely grown in several parts of the world. Sorghum can be grown successfully on poorer soils and in drier conditions than maize. Its energy content is comparable to that from maize up to 13.79MJ/kg.

Its protein content is slightly higher than that of maize. It contains low levels of xanthophylls, linoleic acid, lysine, methionine, tryptophan and fibre. It is also low in calcium but high in phosphorus. It is used to substitute maize to a reasonable extent in livestock feeding.

It is also used in human food in various forms especially in the Northern part of the country. The use of sorghum in livestock feeding is limited by its content of tannin. Although low tannin sorghum has been bred to improve its utilization in poultry.

Tannins are a group of compounds that bind to proteins, thus impairing protein digestion. Tannins also reduces palatability. Guinea corn leaves are used as feed for ruminant animals. However, it must be noted that young sorghum contains cyanogenic glucoside.

The glucoside occurs in the germinated plant and its contents increases as the plant matures and disappears completely when grain appears, glucoside hydrolysis yields hydrocyanic acid (HCN).

3. Rice (Oryza sativa)

Rice is grown locally but principally as human food, though it is useful in livestock feeding. By products obtainable from rice includes rice husk, rice bran, broken rice, rice polishing and rice mill by products.

Rice bran consists of the pericarp or bran layer and germ. The fat and linoleic acid contents of rice bran are relatively high. The protein content is between 12 and 13%. Rice polishing is obtained in the operation of brushing the grain to polish the rice.

The protein content and linoleic content of rice polishing are higher than those of maize. The crude fibre content is low (4.1%). Its energy value is higher than rice bran. Rice mill by-products consist of rice husk, rice bran, rice polishing and broken rice grains. Its crude fibre may be higher than 32%.

Rice mill by-products crude protein is low and fat content 5 – 6 %. Its high crude fibre and its low metabolizable energy (ME) values discourage its use in poultry and swine diets.

Protein and lysine content of cereal crops

Limiting amino acids in cereal protein

4. Cereal Grain By-products

Cereals grain by- products are obtained during the processing of grains into food and drinks for human. The by-products are used mostly for feeding livestock.

Some are now processed into human foods for example oat bran and breakfast cereals.

Examples of cereal by-products include: Wheat Bran, Wheat Shorts, Wheat middling, Wheat mill run, Rice Bran, Rice Polishing, Rice mill by – products, maize Gluten meal, Maize gluten feed, Maize Distillers Dried grains, Hominy feed, Brewer’s dried grains, Sorghum distillers grain, Breweries dried yeast, Torula dried yeast, Dried Bakery products.

Wheat Bran: wheat bran consists of the coarse, outer covering of the wheat in the usual process of commercial milling of wheat. Although of low energy value, wheat bran is useful when low calorie diets are required. It is also cheap. The crude fibre level is above 9.5%

Wheat Shorts: Wheat shorts consist of fine particles of wheat bran, wheat germs. Wheat flour and the offal from the tail of the mill, in the usual process of milling wheat. Because of the endosperm fraction, wheat shorts contain more energy and less crude fibre than wheat bran. It has not more than 7% crude fibre.

Wheat Middling: wheat middling are essentially similar to wheat shorts except for the differences in crude fibre content. Wheat middling consist of fine particles of wheat bran, wheat shorts wheat germ, wheat flour and some of the offal from the tail of the mill. Has not more than 9.5% crude fibre.

Wheat mill Run: This consists of coarse wheat bran, fine particles of wheat bran, wheat flour and the offal from the tail of the mill. The chemical content of wheat mill run is similar to those to those of wheat shorts.

Not more than 9.5% crude fibre. Wheat mill run and the other wheat by- products are ingredients that can be used but in restricted amount in poultry and swine diets.

Rice bran: Rice bran is the by-product of the milling of rice to produce edible rice. Rice bran consists of the pericarp or bran layer and germ of the rice, along with small quantities of hull fragments, and some chipped, broken rice and perhaps CaCO3 as is unavoidable in the rice milling process but which should usually not exceed 5%.

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The fat and linoleic acid contents of rice bran are relatively high. The protein content is below 12 – 13%. The oil gram rice bran is used largely in human diets. The protein content is below 12 – 13%. The oil grain rice bran is used largely in human diets.

Rice bran can be used successfully to replace some part of the grain portion of some poultry and swine diets. As much as possible, rice bran should be avoided in the diets of younger poultry and pigs.

Rice polishing: this is a by – products of rice obtained in the milling operation of brushing the grain to polish the rice. The protein content and linoleic acid content of rice polishing are higher than those of maize.

The product is characterized by relatively low crude fibre content 4.1%. Its energy value is higher than rice bran. There are no special limitations to the use of rice polishing in poultry and swine diets. It is however not as available as rice bran.

Rice mill by – product: this consist of rice hulls, rice polishing, and broken rice grains. Rice mill by-product is in actual fact the total offal obtained in the milling of rice. Its crude fibre content should normally not exceed 32%. Its protein content is low, with fat content of 5.6%.

Maize gluten meal: Maize gluten meal is the dried residue from maize after the removal of the larger part of the starch and germ, and the separation of the bran by the process employed in the wet willing manufacture of corn starch or syrup or by enzymatic treatment of the endosperm it may contain fermented corn extractive and/or maize germ meal.

The amino acid contents of maize gluten meal are much higher than those of maize gluten feed. Like maize the maize by-products are deficient in lysine and tryptophan.

Maize Gluten feed: This is that part of the commercial shelled maize that remains after extraction of the larger portion of the starch, gluten and germ by the processes employed in the wet milling manufacture of maize starch or syrup it may or may not contain fermented Maize extractives and or maize. Contain about 21 – 23% crude protein and 9 -10% crude fibre.

Maize Distillers Dried Grains: These are derived from the fermentation industry particularly the alcohol industry. There are 2 types of maize distillers dried grains, with soluble and maize distiller‘s dried grains, both containing 27% Crude protein.

The crude fibre (12%) is high and energy value relative. Generally, the distillers dried Grains and the distiller dried soluble are by-products obtained after removal of ethyl alcohol by distillation from the yeast fermentation of grains and grain mixture.

Homing feed: this is a mixture of maize bran, maize germ and part of the starchy portion of the maize grain as produced in the manufacture. There have at least 5% Crude fat (ether extract). The fat of homing feed is high in lionoleic acid (3.2%) and the energy content is fairly high.

Brewers dried grains: this is the dried extracted residue of barley alone or in mixture with other cereal grain or grain products resulting from manufacture of beer and may contain pulverized dried spent hops in an amount not exceeding 3% evenly distributed.

Because of its low energy content and high fiber content (over 18%). BDG is more suitable as cattle feed. It is also used extensively in swine production.

Table 5: Proximate composition of some brans and hulls

In summary,cereals contribute significantly to food security and are high in starches that are readily digested by animals. The processing of cereals results in a lot of by- products. The use of these products by animal production is a form of environmental management.

In this article we have learnt that cereals and their by-products are important in animal production however the imbalanced amino acid limits their usage.

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