Q: If a trait has a narrow-sense heritability ($$h^2) of 0.3 $$and the selection differential ($$S) is 50 $$units, what is the expected response to selection ($$R$$)?

$$R = 0.3 \times 50 = 15$$ units

Question 1

Which of the following best describes the difference between genetic merit and breeding value?

Accepted Answer

Genetic merit is the value of an individual's genes based on their own performance, while breeding value is the value of an individual's genes based on their progeny's performance.

Question 2

A dairy farmer selects the top 10% of cows for breeding based on milk yield. If the mean milk production of the original herd is 80 liters/week and the selected cows average 120 liters/week, what is the selection differential ($$S$$)?

Accepted Answer

$$S = 120 - 80 = 40$$ liters/week

Question 3

If the response to selection ($$R) $$for milk yield in a herd is 20 liters/week and the selection differential ($$S) is 40 $$liters/week, what is the realized heritability ($$h^2$$)?

Accepted Answer

$$h^2$$ = \frac{R}{S} = \frac{20}{40} = 0.5$$

Question 4

Which of the following factors can a producer most directly influence to increase the rate of genetic change ($$\Delta G) in a $$population?

Accepted Answer

Selection differential (intensity)

Question 5

A farmer uses genomic testing to select the top 25% of heifers for breeding. Which components of the genetic progress equation are most impacted by this strategy?

Accepted Answer

Selection differential (intensity) and accuracy

Question 6

Which equation correctly represents the response to selection in quantitative genetics?

Accepted Answer

$$R = h^2$ 	imes S$$

Question 7

In the context of producing ability, which of the following traits would be most appropriate to evaluate using this concept?

Accepted Answer

Milk production measured over multiple lactations

Question 8

Which of the following best describes the effect of increasing inbreeding in a dairy cattle population?

Accepted Answer

It decreases genetic variance and may limit future response to selection.

Question 9

A genetic marker is most valuable for selection when:

Accepted Answer

The trait has low heritability and is complex.

Question 10

Which of the following statements about accuracy and reliability in genetic evaluations is correct?

Accepted Answer

Accuracy is the degree of confidence in predicting transmitting ability, while reliability is the precision of repeated measurements.

Question 11

Which pathway to selection is illustrated by selecting sires to breed bulls, as shown in the 'Four Pathways to Selection' diagram?

Accepted Answer

Pathway 1

Question 12

If a trait has a narrow-sense heritability ($$h^2) of 0.3 $$and the selection differential ($$S) is 50 $$units, what is the expected response to selection ($$R$$)?

Accepted Answer

$$R = 0.3 	imes 50 = 15$$ units

Question 13

Which of the following would most likely increase the rate of genetic change in a population?

Accepted Answer

Decreasing the generation interval

Question 14

Which formula correctly represents narrow-sense heritability in terms of additive genetic variance ($$V_A) $$and phenotypic variance ($$V_P$$)?

Accepted Answer

$$h^2$$ = \frac{V_A}{V_P}$$

Question 15

Which scenario would most likely increase the accuracy of genetic merit predictions in dairy cattle?

Accepted Answer

Combining genomic markers with phenotypic records

Question 16

A farmer observes that the mean phenotype of the offspring population is 100 liters/week, while the original population mean is 80 liters/week. What is the response to selection ($$R$$)?

Accepted Answer

$$R = 100 - 80 = 20$$ liters/week

Question 17

Which of the following best explains why it is harder to directly select for traits with low heritability?

Accepted Answer

Low heritability traits are more influenced by environmental factors and less by genetic variation.

Question 18

Which of the following is NOT a component of the genetic progress equation ($$\Delta G$$)?

Accepted Answer

Phenotypic variance

Question 19

How does marker-assisted selection (MAS) improve genetic gain in livestock populations?

Accepted Answer

By increasing the accuracy of selection, especially for low heritability traits

Genetic Selection and Response to Selection in Animal Breeding

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