DISCIUSSION QUESTIONS
1. Describe the origin and characteristics of any ONE breed of your choice for each of the
following livestock enterprises;
a. Beef
[4 marks]
b. Dairy
[4 marks]
c. Pig
2.
[4 marks]
d. Goat
[4 marks]
e. Sheep
[4 marks]
A) A Tuli bull at the University Farm gains 1.4kg/day on a feeding trial in which average
gain is 1.0kg/day. All animals are feed and managed identically and gains are adjusted for
beginning age and weight. If heritability of weight is 0.45, what is the animal’s EBV and the
accuracy of that estimate.
[5 marks]
b) Holsteins (H) in the warm climate zones will yield 4 400kg of milk on average. Given
that a Tuli (T) cow yields an average of 900kg of milk per lactation. The F1 HxT crosses
in Zimbabwe will yield 2 537kg of milk per lactation.
i.
Calculate hybrid vigour as a percentage.
[4 marks]
ii.
If you used a Mashona (M) cow averaging 1 474kg milk per lactation and F1
HxM crosses in Zimbabwe are 519kg above the average parental mean.
Calculate the percentage hybrid vigour.
[4
marks]
iii.
Which cross would you recommend for Zimbabwean conditions? Give
reasons.
3. Describe the economics of successes and failures in animal breeding.
[6 marks]
[20 marks]
4. Assume a population of goat in South Africa has a gene frequency of 0.7 for A1 (A2 allele
has a frequency of 0.3). Twenty percent of the gene for a new population comes from a goat
population in Botswana, where the gene frequency of the A1 allele is 0.5. The gene pool
merges and then the population is transferred to Zimbabwe.
i.
What TWO factors determine the rate of change (delta q)
[4 marks]
ii.
What is the frequency of the A1 allele in the population going to be in Zimbabwe?
[3 marks]
iii.
Determine delta q for the above example.
[3 marks]
5. You are interested in selection on growth per day. You want to estimate the breeding values
for the different boars on own performance. Assume the following values for parameters;
Phenotypic Variation
3 600g2
Additive genetic variation
1 200g2
Population mean
750g2
i.
Calculate the weighting factors and the accuracy of selection
ii.
If the growth of the boar was based on the average of 30 offsprings of different
litters, redo (a).
[5 marks]
[5 marks]
6. How would you set up a small ruminant improvement programme in your district
[20 mark]
7. Describe and explain factors affecting response to selection in common livestock species
[20 Marks]
8. Explain the importance of the following in beef cattle improvement:
a. Birth mass
[4 marks]
b. Weaning mass (205 day mass)
[4 marks]
c. 120 day mass
[2 marks]
d. Yearling and long yearling mass
[5 marks]
e. Maternal effects
[3 marks]
f. Functional efficiency
[2 marks]
9. Describe the following mating systems;
a) Close breeding
[10 marks]
b) Outbreeding
[10 marks]
10. Describe the non-genetic factors that affect milk yield in dairy cows.
[20 marks]
11. How would you set up a small ruminant improvement programme in your district
[20 mark]
12. Selection in animal breeding is considered a formidable task. Describe the problems
associated with performance selection in most developing countries.
[20 Marks]
13. Describe how you can employ the following selection programmes to improve poultry
production.
g. Mass selection
[5 marks]
h. Progeny testing
[5 marks]
i. Selection pressure
[5 marks]
j. Cross breeding
[5 marks]
14. Discuss the importance of biotechnology in the field of animal breeding in Zimbabwe.
[20 marks]
15. Are indigenous species of domestic animals relevant to the success of the local livestock
industry? Provide explanations for your answer.
[20 marks]
16. Describe and explain traits of economic importance in dairy cattle in Zimbabwe.
[20 marks]
WISH YOU THE BEST