Agricultural Science

Animal Nutrition


The food given to farm animal is generally known as livestock feed simply feed. Farm animal need feed for growth, repair of worn out tissues, energy and the general wellbeing of the animals.

Effects of feed shortage in animal production

Feed shortage will lead to the following effects in animal production

  • It leads to low birth weight or loss of weight
  • It result in poor reproduction or delayed puberty or late maturity
  • Poor milk, meat and egg production is recorded, and this leads to drastic

reduction in livestock production

  • Feed shortage can equally lead to high death rate of farm animals
  • It also leads to increased susceptibility to diseases
  • Generally, there is slow growth rate of livestock
  • Draft animals become weak and unable to work.

Classification of livestock feed

Animal feed can be grouped into four main classes. These are:

  • Basal / energy feed or carbohydrate concentrate
  • Protein concentrate
  • Mineral / vitamins supplement
  • Roughages
  • Basal/Energy feeds or carbohydrate concentrates

Characteristics: (i) A Basal/Energy concentrate is the feed that has crude fibre content less than 18%

(ii)           Basal feed refers to feed that are very high in energy or a starchy food e.g. maize, cassava, etc.

(iii)          It is high in carbohydrates or fats

  • It is low in protein
  • It is low in fibre
  • Basal feed is highly digestible
  • It is low in minerals
  • Protein concentrate characteristics
  • Protein concentrate is also a type of feed that has crude fibre content less than


  • Protein concentrate is high in protein
  • They are low in carbohydrate and fats
  • They are low in fibre
  • They are highly digestible
  • They are low in minerals
  • Mineral/vitamins supplements characteristics
  • They are required in small quantities in feed
  • They supplement basal and protein concentrates
  • They are low in energy
  • They are low in protein
  • They are low in fibre
  • They are high in vitamins and minerals
  • They are necessary for growth and development
  • They largely aid food digestion
  • They largely aid resistance to diseases
  • They include minerals, vitamins and essential amino acids.
  • Roughages characteristics
  • Roughages are feeds that have crude fibre content more than 18%
  • They are high in fibre
  • They are low in digestible carbohydrate
  • They are low in protein
  • They have poor or low digestibility
  • Pasture plants such as grasses and legumes form the roughages
  • Roughages exist in different forms such as hey, straw, soil-age and silage.

Hey and straw are referred to as dry roughages

  • Hey: Hay refers to the aerial part of a young and succulent grass or herbage cut and dried for feeding animals. It is a cheap source of food for ruminant animals during the dry season where green grasses are not easily available. Its nutritive value is higher than straw
  • Straw: Straw refers to the aerial part of grass or harvested crops cut and stored for future use. Straw is difficult to digest because the plants are cut after the crops have been harvested. The remains of the plant are then cut, dried and fed to farm animals during dry season. It serves just to keep the animal alive. Wet roughages are referred to as soil age and silage.
  • Soilage: This refers to the process of cutting fresh or succulent grasses and legumes from the field and taking them to the animals in their pens. They have high moisture content and high nutrients. Soilage is also referred to as zero grazing because animals are not allowed to go out to feed on the grasses but the grasses are cut and set to the animals in their pens
  • Silage: This refers to the preservation of green and succulent forage crops under anaerobic condition

Preparation of silage

  • Dig the pit to the size and depth required
  • Cut pasture species at the right stage of maturity, i.e. before flowering
  • Chop the pasture into pieces
  • Wilt the cut and chopped lush (tender) pasture species by spreading them in the

sun for about one day

  • Line the inside of the pit with palm fronds banana leaves or cocoyam leaves
  • Load the chopped, mixed pasture into the pit in stages
  • Compress each layer by rolling heavy substances over it to expel much of the air

which can cause spoilage

  • Sprinkle dilute mineral acid after each layer
  • Deposit other layer and compress the layer each time until the pit is full
  • Finally compress the help
  • Spread polythene sheet or banana leaves over the heap to ward off water
  • Pack a heap of soil on top of the leaves/ or polythene sheet
  • Provide shade over the heap

Method of preparing feed ingredients

  • ‘Blood meal: Collect fresh blood from the abattoir and allow it to clot in the

open. Heat the blood to reduce the moisture content and kill the pathogens. After heating, the blood now in lumps is dried and crushed into powder.

  • Fish meal: Fist meal can be prepared in two major ways. These are: dry and wet


  • Dry process: Collect fresh fish, sun-dry or smoke it reduce the moisture content,

than ground it into powder

  • Wet process of rendering: Collect the fish, heat it with steam. Then, dry it and

crush into powder

  • Groundnut/palm kernel cake: Collect the seeds of groundnut/palm kernel,

crush, and press to remove the oil. Then press the remnants with machines to form cakes, which are dried

  • Cotton-seed meal: collect cotton seeds, grind them and extract oil form the

crushed seeds. Dry the residue or cake later

  • Bone meal: Bone meal can be prepared in two ways. These are: dry and wet


  • Dry process: Collect bones from the abattoir, dry and burn them then crush the

burnt bones to the desired texture

  • Wet process or rendering: Collect bones from the abattoir, heat with steam,

crush and dry the crushed bones

  • Maize/ guinea corn: Remove grains from the cobs, dry them and crush or grind

to desired texture.

Feed ingredient can be prepared or processed for farm animal by making

Into mash and pellets while some have to be cooked before it can be fed to farm animals.

Food nutrients of livestock

There are six classes of food nutrients which are needed by animals for growth and proper development. These are:

  • Carbohydrate (2) Protein (3) Fats and Oil (4) Mineral (5) Vitamins (6) Water
  • Carbohydrates

 Composition: Carbohydrate is made up of carbon, hydrogen and oxygen

Sources: This include maize, guinea corn, cassava, grasses, wheat, potatoes, rice, millet, yam, Cocoyam, plantain, forage grasses, Hey, silage, molasses, spent grains etc.

Functions: Carbohydrate provide energy to farm animals for growth, reproduction, milk production and other activities like build-up of fat.

  • Protein

Composition: Protein is composed of carbon, hydrogen, oxygen and sometimes sulphur, nitrogen and phosphorus.


Animal sources of proteins are fish meal, blood meal, meat meal, feather meal, milk, skimmed milk powder, poultry offal meal, shrimp head meal, whole milk powder, cholesterol, termite, insects, earthworms, eggs etc.

Plant sources of proteins are soya-beans meal, groundnut cake, palm kernel cake, cotton seed meal, sunflower seed meal, cashew nut meal, leguminous forage.

Synthetic sources of protein are methionine, lysine and cysteine which are critical or essential. Amino acids can also be provided.


  • Protein are essential for the growth of young ones
  • They are used for the repair of worn-out tissues or cells
  • They are used in the formation of gametes in reproduction
  • Meat, egg and milk production in livestock depend on the protein level in the


  • They are required for the production of enzymes and hormones in the body of


  • Protein are essential for the sustenance of life
  • They are also necessary for flesh built-up
  • Proteins provide the raw materials for building protective covering such as hair,

nails, horns, hoof, wool and feathers etc.

  • They are also used in the formation of digestive juices and other secretions of

the intestine

  • Proteins are equally useful in the production of antibodies.
  • Fats and oil

Composition: fats are composed of carbon, hydrogen and oxygen

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


  • Fats provide more energy than carbohydrates
  • Fats supply essential fatty acids and fat build-up
  • They also provide fat soluble vitamins
  • They improve the palatability of diet
  • Fat help in the maintenance of body temperature
  • They prevent dustiness of feed
  • Minerals

Composition: Minerals required by animals are grouped into two major classes:

  • Macro-elements or mineral: These are required by animals in large quantity, e.g. calcium, phosphorus, magnesium, potassium, sulphur, sodium and chlorine
  • Trace elements or micro-minerals: These are required by animals in small quantity, e.g. iron, iodine, cobalt, copper, manganese zinc and fluorine.

Sources: These are bone meal, oyster shell, limestone, salt licks

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 gems, forage, grassesAid functioning of the nervous system activation of enzymesHyper-irritability, nervous disorder called tetany
SulphurSalt licks, fish mealConstituents 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.
LodineLodized salt, fish mealConstituent of hormone called thyroxineGoiter
CobaltSalt licksConstituents of vitamins B12. Activate some enzymesGeneral malnutrition
CopperSalt licksAids formation of heamoglobin& iron absorptionAnaemia
FluorineSalt licks, fluorinated waterPrevents tooth decay.Tooth decay.
  • Vitamins

Vitamins are organic substances also required by animals for proper growth and development of the body. Vitamins are grouped into two major classes:

  • Fats soluble vitamins: These are vitamins that are soluble in fats e.g. vitamins A,B,E and K
  • Water soluble vitamins: These are vitamins that are soluble in water e.g. Vitamins C and cabalamine, pantothenic acid, folic acid etc.
Vitamin A (retinol)Fish meal, grasses yellow maizeProper eye sight (or vision) Epithelical cell formation aid reproductionNeghtblindess
Vitamin C (Ascorbic)Grasses, vegetables and fruitsFormation 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 (Egosterol)Vegetables, grasses synthetic vitamin EAids reproduction. As an antioxidantReproductive failure like starility and premature abortions
Vitamin K (phylloquinone)Fish meal, vegatablesAids blood clotting prothrombin formationHaemorrhages i.e. inability of the blood to clot in time
Vitamin B1 (thiamine)Yeast, cereals, green plantsCo-enzyme in energy metabolismPoor appetite, Beri-beri
Vitamin B2 (Riboflavin)Green herbage and milk productsCo-enzyme in protein and fat metabolismSlow growth dermatitis
Vitamin B12 (Cobalamine)Fish meal, milk productsAs co-enzyme in several biochemical reactions. Red blood cell formationPernicious anaemia
Niacin(Nicotinic acid)Yeast, cereals, grassesCarbohydrate oxidationPellagra (reddish tongue)
  • Water: water is very important in livestock management, be it to the animals or to their immediate environment.

Sources of water: Drinking water, from tap, metabolic water from food, rain water, water from rivers and ponds, grasses and fresh fodder.

Function of water

  • Water is provided for drinking purposes
  • It is used for metabolic and digestion of food
  • Water is also used for dipping/drenching animals against ectoparasites and


  • Water is equally used for washing or cleaning animals
  • It is used for cleaning floors, pens or for sanitation purposes
  • Water is also used for milk and meat processing
  • Water is part of the body of any animal
  • It is used for the maintenance of body temperature
  • Water is used for irrigation of pasture
  • Water is a constituent of milk, egg and meat.

Types of ration/diet and their uses

Diet: a diet is defined as the amount of feed regularly given to or consumed by an animal. It is formulated to meet specific metabolic or physiological function such as: growth, lactation, maintenance of pregnancy, reproduction, egg laying etc.

Ration: Ration is the total supply of feed given to a animal in a twenty-four hour period. In other words, ration is the amount of food taken by an animal per day.

Balance Ration: A balance ration is the feed containing all essential nutrients in the correct quantity and in adequate proportion for feeding animals.  Components of a balance ration include carbohydrate, protein, fats and oil, minerals vitamins and water. All these must be taken at the right proportion by farm animal for normal growth, lactation, reproduction and other body activities

Factors normally considered when deciding the type of ration to feed an animal

  • The purpose for which the animal is being kept: If an animal is to be kept for

the purpose of production, such animal will require more feed while those not on production will require little feed.

  • The class of animal: Animals belong to different classes and as such, their feed

requirement will also vary

  • Age of the animal: Feeds are given to farm animals based on their ages, e.g. in

poultry, the chicks (0-6 weeks) requires more nutritious feed (20% crude protein) then growers (6 – 18 weeks) which require about 14% crude protein

  • Animal’s condition of health: The animals that are healthy tend to each more

feed while sick ones consume less

  • Management system: The system of management also determines the type

feed given to farm animals. Quality fed are usually given to animals on intensive system of management while animals on extensive system fend for themselves

  • Physiological state of the animals: pregnant and lactating animals tend to

consume more feeds than animals that are not in these conditions

Types of ration

There are two types of rations. These are:

  • Maintenance ration: This is the type of ration given to farm animals just to maintain normal functioning of the body system. In other words. Maintenance ration supplies enough nutrients just to enable the animal carry on the normal body activities without losing or gaining weight. The ration enables the animal to maintain its body weight but, it cannot be used for production purposes. Examples of maintenance ration include the ration given to ruminant animals like straw, hay during dry season. Maintenance ration can be supplied to breeding animals when they are non-lactating animals when they are not lactating
  • Production ration: This is the type of ration given to farm animals to enable them produce. In other words, production ration supplies nutrients above what is required for maintenance in order to make the animal capable of high production which can be in form of milk, meat, egg, growth etc.

Categories of farm animals that require production rations include:

  • Lactating animals: for milk production
  • Weaning animals: for increase growth
  • Pregnant animals: for maintenance of the foetus
  • Fattening animals: for extra addition of more meat of flesh
  • Broilers: for rapid growth
  • Layers: for more egg production
  • Steaming up or flushing: for animal before mating to produce more ova/ovum.

Ration formulation

Ration formulation involves the careful combination of all the food nutrients in such a way as to meet the nutritional requirement for a particular animal. When formulating ration for farm animals, the following principles should be considered.

  1. The physiological state of the animal, whether for pregnant, dry or lactating or

young animals

  1. The availability of the feedstuff
  2. The composition of the nutrients
  3. The age of the animal
  4. The familiarity of the feed to animals
  5. Palatability of the feed
  6. The cost of the feedstuff.

Careful combination of protein sources (e.g. fishmeal, groundnut cake), fat sources (e.g. palm kernel cake, oils) vitamins, mineral sources (e.g. bone meal, oyster shell) carbohydrate sources (e.g. maize, guinea corn) will provide all the food nutrients to prepare a balanced diet or ration.

To prepare a ration for layers, the following ingredients, for example, are required:

  1. Maize meal (carbohydrate) =              65%
  2. Groundnut cake (protein) =              20%
  3. Fish meal (protein) =              5%
  4. Palm oil (oil) =              4%
  5. Bone meal (mineral) =              5%
  6. Mineral salt (mineral) =              5%
  7. Vitamins supplement (vitamins) =              5%


Malnutrition in farm animals

Definition: Malnutrition is a condition in which an animal shows evidence of nutritional deficiency. It occurs when a ration does not supply all the essential nutrients in the right proportion and quantities. In other words. It results when an animal takes in insufficient food or it eats diet which is deficient in one or more nutrients like protein, vitamins, carbohydrate, mineral and vitamins. This eventually result in nutritional disease. Malnutrition diseases, causes, symptoms and corrections are shown below:

Ricket&OsteomalaciaLack of calcium phosphorus and vitamin DFlexible and curve bones soft-shell eggsAdd fish meal, bone or oyster shell to feed
Perosis (slipped tendon)Lack of chlorine, folic acid, calcium, phosphorus in dietChicken lie down on their kneelsAdd vitamin B-complex and bone meal
Pregnancy toxemia ketosisLack of sufficient energy intake by farm animalsLoss of appetiteFeed carbohydrate to animals
Milk feverLow blood sugarLoss of appetite, constipation and nervousnessFeed oyster shell or bone meal and carbohydrate
Grass tetanyLow iron in bloodLoss of appetite and nervousnessInject iron dextran into the body
Night blindnessLack of vitamins AInability to see clearly in dim lightFeed yellow maize
ScurvyLack of vitamin CLesion around the connective tissuesFeed vegetable and fruits to animals
Beri-beriLack of vitamin B1 (thiamine)Lack of appetite, fatigue and loss of weightFeed yeast, cereals and vegetables.

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