Animal Nutrition: Classifications of Animal Feeds in Detail

Nutrition is defined as the science of feeding: The word nutrition is traceable to Lavoiser in 1750. One of the ultimate objectives of any livestock industry is the conversion into animal products of feeds which are either inedible by man or surplus to his immediate requirements. This article is about animal nutrition and it also covers the classifications of animal feeds as well as the classes of food.

A nutrient is also any element or compound present in the food and required by the animal for proper functioning.

The reasons for feeding livestock are:

  1. Most humans demand a mixed diet as man is an omnivorous being and sometimes, is willing to pay higher prices for foods of animal origin than foods of plant origin. Although man can exist on plant food alone, animal food is very palatable and usually rich in protein, fat and mineral contents.
  2. There are many plant food, particularly forage, that cannot be properly digested by man and at present can only be processed into food suitable for man by giving them to ruminant livestock.
  3. Plants and animals are complementary and the utilization of the both as sources of food may increase total food production per unit area of available land.

Classification of Animal feed


Feeds and feeding stuff are classified according to the amount of nutrients they contain (chemical composition), bulkiness and the use.

The chemical composition gives the potential value of the feed but does not give the actual nutritive value. Hay, silage and forage/roughages are known for their bulkiness.

Therefore Animal Feeds can be classified into four main groups,


  1. Concentrates
  2. Basal or energy feeds
  3. Forages and roughages
  4. Addictive/pre-mix/vitamins/minerals/growth promoters.

1. Concentrates

These are animal feeds prepared from cereals and other materials used in feeding farm animals. They are by-products of plants and animal origin. They contain less crude fibre than roughages and relatively large but varying quantities of carbohydrates, crude protein and fat, together with relatively little water.

They can be utilized by non-ruminant livestock such as pigs and poultry as well as ruminants.

Other Qualities of concentrates include:

  • Less crude fibre
  • High protein content
  • Low in carbohydrate
  • Low in fat
  • Digestibility is high
  • They are low in minerals

Contents of concentrates

Carbohydrates: Processed Wheat, oats, maize, millet, Guinea corn, etc.

Vegetable Proteins: Groundnut cake, cotton, seed cake, soya bean cake, etc.

Animal Protein Supplements: Fish meal, meat meal or tankage, bone meal, blood meal, etc.

Synthetic Protein: Urea (45% Nitrogen or 28.1% crude protein), biurette.

Miscellaneous by-products: Wheat bran, dried brewers grain, rice bran, maize bran, brewers yeast, cod liver oil, sea weed meal, etc.

Additives: Common-salt, grits, drugs, antioxidants, antibiotics, anti-fungal, vitamins, minerals, pre-mix, etc.

Uses of Concentrates

  • Concentrates are used to feed all livestock to supply all the necessary requirements of the body of the farm animal for their optimum growth and production of milk, meat, egg, wool, fur, hides, and skin for use during pregnancy (foetal development).
  • Used in feeding all livestock to supply all the necessary requirements of the body.
  • Mostly used in feeding monogastric animals because of their low fibre content and high digestion rate.
  • Concentrates are blended by feed manufacturers to provide balanced ration for livestock at various stages of growth.

The above are the major features, contents and uses of animal concentrate feed (food).

2. Basal or Energy Feeds

The second class of animal feed is basal feeds which are highly digestible energy-giving feeds, rich in soluble starch, highly palatable to livestock and low in fibre contents.

Features of Basal animal feeds

Basal feeds consist mainly of the following:

  • Grain/cereals: Maize, sorghum, millet, rice, etc.
  • Roots and tubers: Yam, Cassava, potatoes. It is characterized by the following:
  • The cereal grains contain an appreciable amount of protein but usually very low in amino-acids like methionine, lysine, tryptophan.
  • Roots and tubers contain very low amount og proteins and fibres.
  • Both grains, roots and tubers are deficient in some essential amino-acids, minerals and vitamins.
  • Low in calcium and phosphorus as only by-products of cereals.
  • Highly digestible.
  • High carbohydrate.
  • It is low in minerals.
  • It is low in fibre.
  • Low in protein content.

That’s all about Basal or Energy animal feeds and its features.

3. Forage and Roughages

Roughages are characterised by the relatively large amount of crude fibre that their dry matter contains. They are further sub-divided into dry roughages and succulents.

Succulents include practically all growing or fresh vegetables of which forages form a major part. The water content of succulents is always high usually between 75% and 95%.

Forages constitute a complete food for ruminant livestock, as long as they are not grown on soils that are deficient in an essential nutrient.

Forages consists of the following:

  • Legumes like centrosema, pueraria, calapogonium, stylosanthes, etc.
  • Grasses like Guinea grass, elephant grass, rice, bermuda grass.
  • Roots like Cassava, yam, sweet potato, arrow roots, amd breadfruit (although not a root crop has the same feed value).
  • Silage: this varies in nutritive value

The dry roughages imclude mostly grasses, hay, straws and millet. Others are haulms from legume crops like groundnut, dried stalk materials of sesame and cotton.

4. Additives

Additives are another class of animal feed that contains certain chemicals added to rations as supplements to the existing ones. Producers of animal feeds normally add vitamins and mineral supplements to their rations. Specific amino acids like lysine, other substances like antibiotics, hormones, arsenicals, tranquilizers, detergents and in the case of pig rations – additional copper sulphate (CuSO4) are usually added.

Still on animal feeds and nutritions…

Six Components of Animal Food

The food that animals eats is essentially composed of the same elements that form its body and products. Thus, all foods contain the following 6 components:

  • Water
  • Mineral salts
  • Carbohydrates
  • Lipids (fats & oil)
  • Protein
  • Vitamins

Water and mineral salts are inorganic food components while carbohydrates, lipids, protein and vitamins are organic components.

Therefore, carbohydrates (sugars and starches) proteins, lipids (fats) are the energy components of food while vitamins, minerals, water and dietary fiber are the non-energy components of food.

The mineral salt and vitamin requirements are quantitatively small but qualitatively important and as such they are called accessory food while the principal organic foods are called nutrients. Each must be considered with reference to its function within the animal’s body and in relation to each other.

Below are the main 6 components of food:

1. Water

Water as one of the components or classes of food is more vital for the maintenance of animals life than any other food component.

Water is one of the most important chemical compound in the animal body.

It is the biggest constituent of the animal body about 2/3 of the animal body is water.

Functions/features of Water

  • It helps in the regulation of animal body temperature.
  • Assists in enzyme and hormone formation and distribution.
  • Helps in the digestion of food.
  • It helps in the turgidity of muscles and cells of the body.
  • Since water is a universal solvent, it therefore dissolves solutes in the body.
  • Quickens the excretion of waste products from the body.
  • It is the constituent of all body fluids.
  • It accounts for about 65% of the total body weight and 95% of blood.
  • In addition, water is essential for other activities in the farm like (a) washing of tools (b) cleaning of the equipment (c) cleaning of the housing units of animals (d) irrigation (e) washing or cleaning of animals (f) dipping of animals.
  • A major component of milk.
  • It is used in acid/base balancing.
  • In the cerebrospinal fluid, it acts as cushion for the nervous system and helps to maintain homeostasis.
  • It serves as a lubricant in synovial fluid.

Animal Nutrition: Water Requirement

This varies with the age of the animal and the breed of the animal.

For example;

  • The water content in new-born animals ranges from 75-80%, where as mature, fat animals may contain only 50% or less. The average animal probably consists of between 55 and 65% water.
  • Cattle requires about 30 – 40 litres of water per day while sheep, goats, need only about 4 – 5 litres. Pigs, rabbits and poultry requires between 0.5 – 1 litre of water per day.

Sources of animal water

Below are the major sources of water in the animal body:

  • Fresh grasses.
  • Fresh fodder.
  • Metabolic water from the oxidation of fats.
  • Direct drinking of free water.
  • Fruits.

Symptoms of Deficiency of Water in the body

Lack of water in the body causes (1) dehydration (2) restlessness (3) stoppage of some certain functions in the body (4) gasping for breath (5) reduces animal activities like egg-laying and milk production.

2. Mineral Salts

Mineral salt is a component of animal feed/food divided in two groups, they are the macro-minerals like calcium, phosphorus, Potassium, sodium, chlorine, sulphur and magnessiumand they are required in large quantities while the micro-minerals are iron, zinc, copper, bromine, barium, strontium. Note that all animals including human beings require certain inorganic elements called mineral salts.

3. Vitamins

Vitamins are small complex organic materials present in food stuff and required in small quantities by animals. Vitamins are classified into two groups. They are:

  • Fat soluble vitamins
  • Water soluble vitamins

The fat soluble vitamins includes vitamins A, D, E and K while the water soluble vitamins are vitamins B and C.

Quantities of vitamin supplements include: required in small quantities – low energy development, – aid resistance to diseases.

Sources of Vitamins

  • Fish liver oil
  • Green leaves
  • Cod liver oil
  • Yellow Maize
  • Palm oil
  • Carrot
  • Synthetic
  • Fish meal
  • Bone meal
  • Sunlight
  • Milk
  • Groundnuts
  • Yeast
  • Cereals
  • Egg yolk

Some of the features and functions of Vitamins includes: proper night vision, formation of egg shell, maintenance of the surface of the cornea in eyes, essential for bone and teeth formation, necessary for calcium and phosphorus deposition, acts as co-enzyme, essential for blood clotting or coagulation.

Deficiency of minerals in the body of animals includes: night blindness,xerophthalmia,rough coat and scaly skin,low fertility,abortion in pregnant animals,rickets,osteomalacia, soft shells, shell-less eggs,sterility in male and female animals, haemorrhage,inability of clotting to take place, beri-beri, loss of appetite, serious diarrhoea, curied toe paralysis, decreased hatchability of eggs.

4. Proteins

proteins are complex organic compounds of high molecular weight with many and diverse functions within the animals body. Chemically, all proteins consist of carbon, hydrongen, oxygen and nitrogen. In addition, some contain phosphorus and sulphur.

Sources: (1)Groundnut cake (2) palm oil cake (3) palm kemel cake (4) inseed cake (5)cotton seed cake (6) cotton seed meals (7) blood meal (8) cowpeas (9) pear (10)soya bean (11)brewers spent grain (12) milk (13)fish meal (14) whole seed.

Functions of Protein:

  • They are essential in the formation of oxygen-carrying pigment of the blood, collagen antibodies in the chemical units of hereditary transmission.
  • Help in tissue formation.
  • Essential for cell maintenance.
  • Repair worn out cells.
  • Help for eggs, milk and blood production.
  • Very essential for the growth of of young ones.
  • Essential for the formation of enzymes.
  • Necessary for hormone formation.

As you can see, protein is very important to the body and that is why it’s one of the most vital food components.

Protein deficiency causes:

  • Reproductive failure
  • Kwashiokor
  • Slow growth rate
  • Malfunctioning of enzyme, blood, hormone formation
  • In severe cases, maramus and death may occur.

5. Carbohydrates

Carbohydrate is a popular component of food that consists of chemicals like carbon hydrogen and oxygen. They are classified into simple sugar, complex sugar, starch and cellulose.

Cellulose can only be digested by ruminants while the others can be digested by other animals.

Sources of carbohydrates includes: tubers like cassava, yam, sweet potato, Irish Potato, Corn like maize, Millet, guinea corn and wheat. Others are plantain, banana, forage, spent grain, molasses, etc.

Functions of Carbohydrate

  • Production of energy in the body
  • Can be transferred and stored as fat
  • Help in milk productions

Meanwhile, the deficiency of carbohydrate will result to emaciation and general weakness.

6. Fats & Oil (Lipids)

This component of food mainly contain carbon, hydrogen and oxygen. Facts are solids at room temperature and are got from animals while oil is liquid at room temperature and are got from animals. Fats come in different colors, depending on the rate at which the animal converts its food into fats. White fats are formed when species of animals convert the assimilated food into fats immediately, while yellow fats result from delay in converting assimilated food into fats.

Sources of Fats and Oil

  • Groundnut cakes
  • Palm oil
  • Palm kernel cake
  • Linseed cake
  • Cotton seed cake
  • Milk
  • Lard
  • Tallow
  • Whole seed of groundnut, oil palm, cotton, etc.

Functions of Fats & Oil

  • Provide the richest and highest amount of energy
  • Help to also build up fats
  • Help in temperature regulation
  • Insulate the body
  • They are the sources of the fat soluble vitamins like A, D, E and K
  • Reduce hunger and restlessness
  • They form parts of cell membrane e.g. phospho-lipids
  • As body building materials.

You can also include “fiber” as the seventh class of food.

Animal nutrition is a vast topic and I hope this articles touches the key points and most of your queries on it. For better growth, all animal should be fed with balanced diet which contains all the 6 components of food. So when you think of animal feeds, consider the classes of food for a healthy living.

The Author

Mr. Wisdom

Mr. Wisdom is a tech guru who turned his passion for ICT into a successful entrepreneurial career. He believes in the power of technology to improve our lives and businesses, and enjoys sharing personal anecdotes about how tech gadgets have transformed his routine and fueled his journey. He is constantly immersed in the latest gadgets and is eager to help others navigate the ever-evolving digital landscape.


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  1. I need contact with you

  2. Crude fiber can be digested by monogastric as well but in low quantities

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