Farm livestock are divided into two broad classes; those that are ruminants, and those that are non- ruminants. Cattle, sheep and goats are ruminants, their natural food being grass. Horses, pigs, poultry and rabbits are non-ruminants. The natural food for horses is grass, but pigs and poultry eat mainly cereals. Rabbits eat both green foods and cereals. Livestock products are:

  • Cattle:        milk and beef
    • Sheep:       lamb, mutton and wool
    • Goats:        milk and meat
    • Pigs:            meat
    • Poultry:      eggs and meat
    • Rabbits:     meat
      Carbohydrates: any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose. They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body.

Horses are kept for working and riding, although in some countries they are used for meat, particularly when they come to the end of their useful lives.

The role of ruminants in farming is to convert grass, in veld or pastures into human food, meat or milk. Grass is not a human food, and were it not for the ruminant animal, the large areas of the world covered with grass would be useless. The ruminant converts this grass into human food, which is particularly valuable because it is very high in protein, and it is done reasonably quickly and efficiently. Non-ruminants, on the other hand, are chiefly used to convert the starchy, high carbohydrate foods such as cereals into high protein food. The problem is that the cereals fed to pigs and poultry are themselves human foods and the conversion of these foods into high protein meat and eggs is not, a very efficient process.


Farm livestock are found throughout the world. Most farms keep some form of animals. Their roles vary greatly. On some farms they play a major part in the farming pattern producing most, or all of the farm income, while on other farms, they are kept just as a sideline.

In Africa, farm animals are found over the whole continent. In the ranching areas they are the only source of income to the farmer. In the cropping areas, they are integrated with the crops in order to utilise areas which cannot be cropped, and to use up crop residues; they provide an extra source of income to the farmer. An important point to remember is that the profit margins from livestock are not as great as those from crops. This applies in most countries. Unless the farmer exercises the maximum efficiency to his enterprise, livestock farming can easily become unprofitable.

An efficient, successful, livestock farmer is one who is in full control of his animals, knows what makes them profitable, and knows how to adapt to changing conditions and costs. He should know which animals are best suited to the conditions on his farm and the most beneficial and economical ways of feeding them.

He should be aware of the common diseases, the symptoms which tell him that an animal is sick, and


above all, be prepared on keeping an eye on his animals. Most disease can be successfully treated if spotted in good time, but, if treatment is neglected, you could lose the animal, and dead animals are worth nothing. The farmer should know exactly how many animals he has on the farm, where they are, what they are being fed and who is in charge of them. As with all aspects of farming, attention to detail is the secret of success.

In the same way that the motor mechanic must have a good working knowledge of engines, so the livestock farmer must have at least some idea of the internal workings of his animals. The study of the structure and function of animals is usually divided into two parts; anatomy, which is the study of the structure of the animal, and physiology, which is the study of how the various organs of the animal function. In order to simplify matters, we have put the two subjects together in this course and called it Animal Structure and Function, but remember, it covers the two topics of anatomy and physiology.


The following topics will be covered in the Animal Structure and Function Course, and in the order given below:

  • Cells:

a) Various types of animal cells and tissues.

  • Digestion:
  • Structure of the digestive tracts of ruminants and non-ruminants.
  • Digestion in the stomach, both simple and ruminant.
  • The actions of the pancreas and liver.
  • Absorption of the nutrients after they have been broken down, and the utilisation of the end products of digestion.
  • Circulation:
  • The structure and actions of the heart.
  • The blood system and the veins, arteries and capillaries.
  • The function of blood, and its role in defence against disease.
  • Lymph vessels, nodes and the spleen.
  • Immunity.
  • Respiration:
  • The function of the lungs.
  • Gaseous exchange.
  • Control of respiration.
  • Kidneys:
  • Structure and function.
  • Water balance.
  • Nervous System:
  • The brain and the spinal cord.
  • Receptors and special sense organs.
  • Control of the sympathetic system.
  • The endocrine system.
  • Reproductive System:
  1. The male reproductive organs.
  2. Hormones.
  3. Sperm production.
  4. The female reproductive organs.
  5. Oestrus and ovulation.
  6. Pregnancy and parturition.
  7. The development, structure and function of mammary glands.
  8. The formation and secretion of milk.
  • Bones and Muscles:
  • The structure of the skeleton.
  • Joints in bones.
  • The function of muscles.
  • Meat quality, carcass cuts and meat grading.
  • Growth and Development:
  • The physiology and rates of growth.
  • Differential growth.
  • Effects of nutrition on growth.
  • Compensatory growth.

Although this may seem a rather formidable list, by going through it systematically and carefully, you should have no problems, and remember that this is important information if you intend to have dealings with livestock.