Animal Breeding and Response to Genetic Selection

Question 1

What are the three levels of a breeding pyramid?

Answer 1

Elite, multiplier, commercial flocks & herds

Question 2

Why is the Meidam pig used in crossbreeding?

Answer 2

Highly prolific, more teats, increased milk yield, calm maternal temperament, production durability, stress free, commercial carcase

Question 3

What is heterosis?

Answer 3

Hybrid vigour, extra performance above a mid-parent mean

Question 4

How do you calculate the response to selection?

Answer 4

R = S (selection differential) x h2 (heritability)

Question 5

How do you calculate the response to selection per year?

Answer 5

Divide by the generation interval (L)

Question 6

How can the performance of relatives be used?

Answer 6

Related animals have genes in common and so the performance of relatives can provide clues to the genetic merit or breeding value of the candidates for selection

Question 7

What are the possible methods used for selection?

Answer 7

Pedigree selection – selection using an index combining information on ancestors’ performances
Performance test – selection based on the animal’s own performance
Sib pair test – selection based on information from siblings
Progeny test – selection based on the performance of an animal’s offspring

Question 8

What is the ultimate result of continued inbreeding?

Answer 8

Terminal lack of vigour and probable extinction as the gene pool contracts, fertility decreases, abnormalities increase and mortality rates rise