Question 3
QUESTION 3
(a) State two functions each of the following reproductive hormones in livestock:
(i) progesterone;
(ii) androgen;
(iii) oestrogen;
(iv) luteinizing hormone [8 marks]
(b) Complete the table below.
Common name |
Botanical name |
Type of forage |
Elephant grass |
(i) |
Grass |
Tropical kudzu |
(ii) |
Legume |
Gliricidia |
(iii) |
(iv) |
(iv) |
Andropogon gayanus |
(vi) |
(vii) |
Centrosema molle |
Legume |
Leucaena |
Leucaena leucocephala |
(viii) |
Bahama grass |
(ix) |
Grass |
(x) |
Panicum maximum |
Grass |
[10 marks]
(c) Mention two methods of mating in animal production. [2 marks]
Observation
Question 3 was a bit challenging for many candidates and marks were below average.
- Although many candidates were able to state the functions of progesterone
and androgen, very few of them could state the functions of oestrogen
and luteinizing hormone.
- Many candidates displayed poor knowledge of botanical names and type of common forages. They also failed to follow the scientific convention of writing botanical names of species; thus losing marks.
The expected answers include:
(a) Functions of reproductive hormones in livestock
(i) Progesterone
- Ensures implantation of fertilized ovum
- Maintains pregnancy
- Inhibits oestrus
- Causes the development of alveoli in the mammary gland
- Supports lactation
- Supports thyroid function
(ii) Androgen
- Initiates spermatogenesis
- Responsible for the development of male secondary sexual characteristics
- Maintains sex drive/libido
- Sustains the life of sperms in the epididymis
- Reduces fat deposition
- Enhances muscular growth
- Enhances skeletal growth
- Promotes the growth of accessory sex glands
(iii) Oestrogen
- Stimulates growth of ducts in the udder
- Promotes egg production
- Induces rapid multiplication of epithelium in the vagina
- Increases blood supply to uterus
- Increases the water content of uterus
- Prepares the uterus for reception of fertilized ovum
- Stimulates the development of female secondary sex characteristics
- Increases cilliary activities and mucous secretion in the vagina
(iv) Luteinizing hormone
- Causes rupture of graafian follicle
- Stimulates release of ova
- Stimulates secretion of oestrogen and progesterone
(b) Completion of table
Common name |
Botanical name |
Type of forage |
Elephant grass |
(i) Pennisetum purpureum |
Grass |
Tropical kudzu |
(ii) Pueraria phaseoloides |
Legume |
Gliricidia |
(iii) Gliricidia sepium |
(iv) Browse plant/legume |
(v) Gamba grass |
Andropogon gayanus |
(vi) Grass |
(vii) Centrosema/Centro |
Centrosema molle |
Legume |
Leucaena |
Leucaena leucocephala |
(viii) Browse plant/legume |
Bahama grass |
(ix) Cynodon dactylon |
Grass |
(x) Guinea grass |
Panicum maximum |
Grass |
(c) Methods of natural mating in animal production
- Pen mating
- Flock mating /herd mating
- Hand/stud mating
- Pasture mating