Agricultural Science



  • Animals are fed for the purpose of production and body maintenance.
  • The edible material given to animals is called food.
  • It is digested, absorbed and utilized in the body.
  • Nutrients are organic and inorganic substances contained in the food materials

Components of Food material

  • Water, protein,
  • Carbohydrates,
  • Fats and oils,
  • Vitamins
  • Mineral salts.



  • Free water (through drinking)
  • Bound water (contained in feeds).
  • Metabolic water (obtained from oxidation of food).


  • Regulates body temperature.
  • Transport agent in the body.
  • Universal solvent in the body.
  • Gives shape to the cells (turgidity).
  • Acts as a lubricant.
  • Acts as constituent of body fluids.

Factors Determining the Requirements of Water by Livestock

  • Production level.
  • Amount of dry matter eaten.
  • Temperature of the surrounding area.
  • Type of animal.
  • Type of food eaten.



  • Groundnut cakes,
  • cotton seed cakes,
  • fish meal,
  • meat meal.


  • Growth of new tissues.
  • Repair of worn out tissues (body building).
  • Synthesis of antibodies.
  • Synthesis of hormones and enzymes.
  • Production of energy during starvation.

Digestion of Proteins

In non-ruminants, protein digestion takes placed in the stomach.

  • Food is subjected to mechanical breakdown through chewing into small particles.
  • Protein is acted on by enzymes to turn into amino acid which is assimilated into the bloodstream.

In ruminants, protein digestion initially takes place in the rumen.

  • Food is acted on by micro-organisms into microbial protein.
  • Later, enzymatic action takes place in the “true stomach” or abomasum where proteins are broken down into amino acids which are then assimilated into the bloodstream.



  • Cereals,
  • tubers
  • commercially mixed feeds.


  • Supply energy and heat to the body.
  • Excess is stored in form of fat for insulation of the body.

Digestion of Carbohydrates

In non-ruminants:

– Carbohydrate feeds are broken down by chewing into small particles.

– Then enzymatic action further breaks down carbohydrates into glucose, fructose and galactose which are then assimilated into the bloodstream.

In ruminants:

Mechanical breakdown of carbohydrate feeds is followed by microbial activities which break down cellulose into volatile fatty acids.

These are absorbed through the rumen walls.

Some carbohydrates are broken down by enzymatic action in the “true stomach” or abomasum.

Fats and Oils


  • Cotton seeds,
  • soya beans


  • Supply energy and heat to the body.
  • Excess is stored as fat adipose tissues.
  • Source of metabolic water in the body.
  • Required for the development of neural system.
  • Insulator in the body.

Digestion of lipids in Ruminants

  • Fats are hydrolyzed in the rumen into fatty acids and glycerol.
  • Others are fermented into propionic acid,
  • The shorter chains are passed to the true stomach where enzymatic action takes place.



  • Green materials,
  • Dried grass

Ffish liver oil.


  • Protects the body against diseases.
  • Regulate the functions of all parts of the body.
  • It acts as a co-enzyme in the body.


  • Vitamin A,
  • Vitamin B2
  • Vitamin C,
  • Vitamin E
  • Vitamin K.



  • Salt licks,
  • Bone meal,
  • Legumes


  • Form part of the tissues such as bones and teeth.
  • Work together with the enzymes.
  • Act as acid -base balances. Act as
  • Electrolyte in the body. Regulate
  • Osmotic balance in the body.


  • Calcium,
  • phosphorus,
  • magnesium,
  • iron,
  • iodine,
  • sodium

Calcium and phosphorus

– Needed for teeth and bone formation.

– Lack of these minerals leads to rickets, osteomalacia.

–  Lack of iron leads to anaemia.

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