SS 3 Agricultural Science (1st, 2nd & 3rd Term)




  • Selection
  • Culling
  • Identification of farm animals
  • De-beaking
  • De-horning
  • Castration
  • Servicing
  • Incubation
  • Candling
  • Hatching



Selection is the process of picking from a group of animals those animals with breeding value as the parent to maximize genetic gain. Animals with desirable characters like good meat production, egg laying abilities, resistance to diseases, excellent mothering abilities, good milk producers etc are selected. Selection is grouped into two main classes.

  1. Natural selection: This is the ability of an individual animal to survive and reproduce during unfavourable environmental conditions. Those that are unable to survive die off.
  2. Artificial selection: This type of selection is carried out by man through close monitoring of the animals. The man uses his intelligence to select and mate animals. Four types of artificial selection include
  1. Mass selection: Animals with desirable characteristics are selected in preference to those not possessing them from a large group of animals.
  2. Progeny selection: The animals are selected based on the performance of their offspring. Best mothers are retained.
  3. Family selection: The animals are selected based on the performance of their relatives. It is useful when the family is large and heritability is low.
  4. Pedigree selection: The animals are selected based on the performance of their ancestors. It is based on heredity.



  1. It ensures that animals with desirable qualities are selected.
  2. Animals from best breeds are bred for distribution.
  3. It reduces the spread of diseases and parasites associated with breeding stock.
  4. It increases the rate of reproduction and yield.
  5. It reduces the cost of management.



  1. Labour requirement is high.
  2. It is time consuming.
  3. It requires expertise which may not be readily available.
  4. It brings about the elimination of some desirable traits.



  1. Differentiate between progeny and pedigree selection.
  2. Mention five importance of selection



Culling is the removal of undesirable or unproductive animals from the farm. It may take the form of mass culling when the entire flock is removed e. g. old layers or selective culling when one or more animals are removed. Culling is done for the following reasons

  1. Failure to reproduce or low rate of reproduction.
  2. Ill health
  3. Cannibalism
  4. Low eggs production in poultry.
  5. Fighting among animals.
  6. Pronounced deformation of parts of the body.
  7. Over weight due to excessive fat.



  1. It reduces the cost of production.
  2. It reduces the cost of maintenance (feeding, health).
  3. It ensures greater production of animals.
  4. It ensures elimination of animals with undesirable qualities.
  5. It controls bad habits or vices from spreading to other animals.
  6. It creates space for the comfort of other animals.
  7. It controls diseases from spreading to other animals.



  1. What is culling?
  2. Give five reasons for culling in a animal farms



Identification of farm animals is essential for farmers to prove ownership, accurate recording and proper management of animals. Most common methods of identifying farm animals include branding, tattooing, ear-notching, chaining, nose punching etc.

  1. Branding: – It is a special marks in form of letters, numerals, designs make on some parts of the body of farm animals such as cattle, sheep, goat and pig. It is easy and cheap to carry out but it may be painful to animals and it can cause infections and death. It is usually carried out on horns, cheeks, body sides, thigh, shoulder, ore legs or below the shank. It could either be done with the use of heat generating machines (hot branding) or cold generating machine (cold branding). The cold branding is painless to the animal but more expensive for the farmer.
  2. Tattooing: – It is the piercing of outlines of desired numbers and letters made from metal pins on the skins or ears of farm animals and then incorporate a black pigment into these punctures. It is easy and cheap to carry out but can easily tear off the skin of farm animals.
  3. Ear-notching: – It is the practice of making small cuttings (a common code) on the ears of farm animals such as goat, cattle, sheep and pig. It is one of the best, cheap and most satisfactory methods of identifying farm animals.



It is the partial removal of beaks of birds using a debeaker. De-beaking is done to prevent pecking of other animals, egg eating, cannibalism and feather removal. It should be done carefully to prevent stress and permanent damage to the beak and tongue of the birds.



De-horning is the removal of horns of mature farm animals while disbudding is the removal of young horns from young animals using hot iron, saw, chemical or electric dehorner. It makes handling of farm animals easier. It prevents injuries to the body of other farm animals and prevents secondary infections caused by horn injuries. It must be carefully done to prevent injuries and infections to the animals.



  1. Differentiate between tattooing and branding
  2. State three reasons each for i) de-beaking ii) de-horning



This is the mating of a male animal with a female animal identified to be on heat. The breeder should watch out for signs of heat in the female animal. Natural mating such as flock, pen and stud mating can be employed.



Castration is the removal of testes in male animals. It is done in animals that are not required for breeding purposes. Castration is carried out when animals are young by open incision, buddizzo or rubber rings. It prevents indiscriminate mating, quickens the fattening up of the animals and the quality of meat. It also makes the animals to be calmer and easy to handle. It causes pain to the animal and infections if not properly treated.



Incubation is the keeping of fertilized eggs warm so that the embryo will develop to produce young birds. Fertilized eggs are incubated for 21 days using incubators which supplies adequate temperature, ventilation and relative humidity until the eggs are hatched. The eggs are turned regularly to expose all sides to the incubator conditions.



This is the process of passing light through set eggs to identify and separate fertile eggs from unfertile ones. It is usually carried out on the 6th and 18th day of incubation. Other management practices includes brooding, weaning, flushing, steaming up, creep feeding



  1. Define i) servicing ii) candling iii) incubation in poultry
  2. What is castration? Give three importance of castration.



Essential Agricultural Science for senior secondary school by I. O Iwena chapter 46, pages 423 – 431.

Answer revision questions 2 and 8 on page 431.

Prescribed Agricultural Science chapter 5, page 279, 303, 319, 321



  1. Which of these is not a method of identifying farm animals a) chaining b) tattooing c) candling d) ear-notching
  2. The following are routine practices in poultry farm except a) incubation b) brooding c) tattooing d) de-beaking
  3. Identification and removal of unfertilized eggs from the incubator is aided with the use of as a) candler b) culler c) hatcher d) incubator
  4. Which of these is not a reason for carrying out selection in animal farms a) good meat production b) resistance to diseases c) maximize genetic gain d) cannibalism
  5. The following except one are factors to be considered in incubation a) feeding
  6. b) temperature c) relative humidity d) Air flow



  1. State three advantages and disadvantages of selection in farm animals.
  2. Describe briefly three routine practices in cattle management


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