Agricultural Science Notes

Animal Nutrition


  • Meaning of Animal Nutrition
  • Classification of livestock feeds
  • Food Nutrients of livestock


Animal nutrition is the process by which an animal obtains nutrient necessary for its healthy growth and development.


  1. Animal feeds are needed for growth
  2. Useful for repair or worn out tissue
  3. It provides energy
  4. It is useful for the general well-being of the animal.
  5. It aids animal’s resistance to diseases.
  6. It influences maturity in animals.
  7. It aids optimal production in animals.


Feed refers to the food given to animals. They contain nutrient element either alone or in combination with other substances which supports the healthy growth and development of livestock.


Animal feeds can be classified into four main groups according to the digestibility, quantity of fibre, quantity required and moisture in the feed. The four groups of feeds are;

  1. Concentrates: They are fee with a low proportion of fibre and water content. They are easily digested by farm animals. Concentrates can be further be subdivided into two groups: Those containing a high proportion of carbohydrates are called carbohydrate concentrates/basal feed/energy feed e.g maize, guinea corn, cassava e.t.c while those with a high proportion of proteins are called protein concentrates e.g beans, peas, cotton seed, sunflower seeds and heads, groundnuts, palm kernel and animal products such as meat, blood meal, bone meal, fishmeal and milk.
  2. Roughages: Roughages are very low in protein and carbohydrate but high in fibre. They are not easily digested by animals, therefore are fed together with concentrate foods for young animals and those kept for milk and meat production. Examples are hay, groundnut hulls, straw, bean pods and maize stover.
  3. Succulents: These have high water content. They are easy to digest. Examples are freshly cut/lush grass and legume plants (soilage), pumpkin, silage, melons and most green crops.
  4. Supplements (minerals and vitamins): they are required in small quantities, low in energy, protein and fibre but high in vitamins and minerals. They aid digestion and increase animals resistance to diseases. They are available in basal and protein concentrate feeds. Other sources are bone meal, oyster shell, salt licks etc.
  1. Basal/Energy Feed or Carbonhydrate Concentrates


  1. They are fed with crude fibre content less than 18%
  2. They are high in energy and starchy food e.g. maize and cassava
  3. It is high in carbohydrates or fats
  4. It is low in proteins
  5. Low in fibre
  6. It is highly digestible
  7. It is low in minerals
  • Protein Concentrate


  1. They crude fibre content is less than18%
  2. Protein concentrate is high in protein
  3. They are low in carbohydrates and fats
  4. They are low in fibre
  5. They are highly digestible
  6. They are low in minerals
  • Mineral and Vitamin Supplements


  1. They are required in small quantities in feeds
  2. They supplement basal and protein concentrates
  3. They are low in energy
  4. Low in protein
  5. Low in fibre
  6. High is vitamin and minerals
  7. Necessary for growth and development
  8. They aid food digestion
  9. They aid resistance to diseases
  • Roughages


  1. They are feeds which contain crude fibre that is greater than 18%
  2. They are high in fibre
  3. They are low in digestible carbohydrates
  4. They are low in protein
  5. They have poor or low digestibility
  6. Pasture grasses and legumes form roughages
  7. Roughages exist in different forms which are; hay, straw, soilage and salvage.

Hay: It refer to the aerial part of a young and succulent grass or herbage cut and dried for feeding animals

Straw: This is the aerial part of grass or harvested crops cut and store for future use. They are difficult to digest. Both hay and straw are called dry roughages

Soilage: This refer to the process of cutting fresh or succulent grass or legumes from the field and taking them to the animals in their pens. It is also called zero grazing

Silage: This refers to the preservation of green and succulent forage crops under anaerobic conition.


Describe the preparation of silage.


  1. What is animal nutrition?
  2. State the classes of animal feed


These are the raw materials used in production of animal feeds. These includes; blood meal, fish meal, groundnut cake, palm kernel cake, cotton seed meal, bone meal, maize, guinea corn etc.


Explain the method of preparing the ingredients mentioned above.


There are six classes of food nutrients. These are;

  1. CARBOHYDRATE: It is made up of carbon, hydrogen and oxygen.

Sources: Maize, guinea corn, cassava, grasses, wheat, potato, rice, millet, yam, hay, silage, potato, rice millet, yam, hay, silage potatoes etc


Provides energy to farm animal for growth, reproduction, milk production and other activities.

  • PROTEIN: It is composed of carbon, hydrogen, oxygen and sometimes sulphur, nitrogen and phosphorus

Sources: The sources of animal proteins are; fish meal, blood meal, meat meal, milk, earthworms, eggs  e.t.c. Plant proteins sources are; soyabeans meal, groundnut cake, palm kernel cake, cotton seed meal, sunflower seed meal, cashewnut meal and leguminous forage. Synthetic sources of proterins are; methionine, lysine, cysteine


  1. Essential for the growth of young animal tissue
  2. They are used to repair worn out tissue
  3. They are used in the formation of gamates in reproduction
  4. They are needed for the production of enzymes
  5. They are necessary for flesh built-up
  6. Essential for sustenance of life
  7. Help to provide raw materials for building protective covering such as hair, nails roof, wool feather e.t.c.
  8. They are useful in the production of

Fat are composed of carbon, hydrogen, and oxygen

Sources: These are palm oil, palm kernel cake, groundnut cake, coconut meal, cotton seed cake, milk, lard and fallow.


  1. Fats provide more energy than carbohydrates
  2. Fat supply essential fatty acids and fat build-up
  3. They provide fat soluble vitamins
  4. They improve the diet
  5. They help in the maintenance of body temperature
  • MINERALS: these are essential elements needed by the body but which the body cannot produce. They are grouped into two major classes:
  • Structural mineral elements: Carbon, Hydrogen, Oxygen and Nitrogen
  • Mineral elements is further divided into
  • Macro-elements or mineral: These are required by animals in large quantity e.g. calcium, photophorus, magnesium, potassium, sulphur, sodium and chlorine
  • Trace Elements or micro elements: These are required by animals in small quantity e.g. iodine, cobalt, copper, manganese, zinc and fluorine.

Sources are born meal, oyster shell, limestone and salt licks


  1. It helps to ensure good health and productivity
  2. Present in muscles for muscle contractions
  3. Constituent of milk, egg and meat
  4. Help in the formation of hormones.
  5. Maintain PH balance of body fluids
  6. They prevent diseases
  7. Regulate blood clothing
  8. Help in bone and teeth formation
  9. Prevent tooth decay
CalciumBone meal, oyster shell, limestone, milk rock calcium phosphateBone and teeth formation Egg shell formation Blood clottingRicket, osteomalacia, soft egg shell. Retarded growth
PhosphorusBone meal, Dicalcium phosphate, fish mealBone and teeth formation; Acid-base balance; Egg shell formationRicket, Lack of appetite. Osteomalcia
MagnesiumSalt licks, wheat germs, forage, grassesAid functioning of the nervous system. Activation of enzymesHyper-irritability, Nervous disorder Called tetany
Sodium and ChlorineCommon salt, salt licks, fish mealRegulates acid-base balance; Maintenance of osmotic pressure, constituents of Hcl Improves pleasant taste of feed.Reduced growth and weight; decline in appetite.  
SulphurSalt licks, fish mealConstituent of protein and amino acids like cysteine, methionePoor growth
IronYeast, iron injection, salt licksConstituent of haemoglobin in red blood cell. Constituent of protein called myoglobulineAnaemia e.g. baby pig anaemia of piglets.
IodineIodined salts, fish mealConstituent of hormone called thyroxineGoitre
CobaltSalt licks, Activate some enzymesConstituents of vitamins B12General malnutrition
CopperSalt licksAids formation of haemoglobin & Iron absorptionAnaemia
FlourineSalt licks, fluorinated waterPrevents tooth decayTooth decay.
  • VITAMINS: are organic substances also required by animals for proper growth and bosy development. The types are;
  • Fat Soluble Vitamins: These are vitamins which are soluble in fat e.g. A,D,E and K
  • Water Soluble Vitamins C and B-Complex. Examples of vitamin B-Complex are; cobalamine, pantothenic acid and folic acid.
Vitamin A (retinol)Fish meal, grasses, yellow maizeProper eye sight (or vision), Epithelical cell formation, Aid reproduction.Nightblindness
Vitamin C (Ascorbic) acidGrasses, vegetables and fruits.Formation of connective tissues, bone and dentineScurvy
Vitamin D (Calciferol)Bone meal, fish meal and sunlightAids bone and teeth formation, egg shell formationRicket, Osteomalacia, soft shell egg.
Vitamin E (Tocopherol)Vegetables, grasses, synthetic vitamin EAids reproduction. As an antioxidant.Reproductive failure like sterility and premature
Vitamin K (phylloquinone)Fish meal,  vegetablesAids blood clotting. ProthrombinHaemorrhages i.e inability of the blood to clot in time.
Vitamin B1 (Thiamine)Yeast, cereals, green plantsCo-enzyme in energy metabolismPoor appetite, Bere-beri
Vitamin  B2 (Riboflavin)Green herbage and milk productsCo-enzyme in protein and fat metabolismSlow growth, Dermatitis
Vitamin B12 (Cobalamin)Fish meal, milk productsAs co-enzyme in several biochemical reactions. Red blood cell formationPernicious anaemia.
Vitamin B3 Niacin (Nicotinic acid)Yeast, cereals, grassesCarbohydrate oxidationPellagra

Sources of water; tap, feed, rain, rivers, pond and fresh fodder.


  1. Water is provided for drinking purposes
  2. It is used for metabolic and digestion of food
  3. For dipping/drenching animal against ectoparasites
  4. For washing or cleaning of animals
  5. For sanitation, cleaning of floor and pens
  6. For processing animal products
  7. For maintenance of body temperature
  8. For irrigation of pasture
  9. It helps to get rid of waste products in the body
  10. Helps to maintain body turgidity


  1. Helps to fight against pathogen
  2. Helps to heal sore and wounds in animals
  3. They increase absorption of nutrient from digestive tract


  1. State five functions of proteins.
  2. What are macronutrient?


Diet: is defined as the feed formulated to meet specific needs of an animal. It is also referred to as the amount of feed regularly given to or consumed by animal. It is formulated to meet specific metabolic or physiological functions such as growth, location, maintenance of pregnancy, reproduction or egg laying.

Ration: is the total supply of food given to animals in a twenty four hour period.

Balanced Ration: A balanced ration is the feed containing all essential nutrients in the correct quantity and in adequate proportion for feeding animals.

Types of balanced ration

  1. Maintenance Ration: This is given to farm animals just to maintain normal functioning of the body system.
  2. Production Ration: This is the type of ration given to farm animals to enable them to produce.

Factor to be considered when deciding the type of Ration to feed an Animal

  1. The purpose for which the animal is kept
  2. Age of the animal
  3. Animal’s condition of health
  4. Management System
  5. Physiological state of the animal

Categories of farm animals that require production ration are;

  1. Lactating  animals
  2. Weaned animals
  3. Pregnant animals
  4. Fattening animals
  5. Broiler
  6. Layers
  7. Steaming up or flushing


  1. What is balanced ration?
  2. Distinguished between production and maintenance ration
  3. State five functions of vitamins
  4. State five functions of water


  • Essential Agricultural Science for senior Secondary School by O.A. Iwena Chapter 33, pages 329-338
  • Answer the following questions from WAEC PAQ 1995 theory question 7, 2012 theory question 8 and 2014 theory question 4


  1. ____ is essential for bone formation A. iron B. calcium C. carbon D. lodine
  2. Night blindness is as a result of lack of vitamin ____ A. A  B. B C. C D. D
  3. Ricket is as a result of deficiency of vitamin ____ A. A  B. B C. C D. D
  4. Which of these is a micronutrient A. calcium B. manganese C. magnesium D. sulphur
  5. Goitre is as a result of deficiency of ____ A. iron B. cobalt C. copper D. lodine


  1. a. What is a nutrient?

b. List five characteristics of roughages.

  1. a. Define (i) Diet (i) nutrition (iii) production ration

b. State five functions of proteins.

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