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Flashcards in Exam 3 Deck (35):
1

Name a qualitative simply inherited trait.

Coat color

2

Name a qualitative polygenic trait.

Litter size

3

What special name is given to qualitative polygenic traits?

Threshold traits

4

Name a Quantitate polygenic trait

Ribeye Area

5

Rank the trait types in order of easiest to to most difficult to select for.

1. Qualitative Simply Inherited
2. Quantitative Polygenic
3. Qualitative Polygenic

6

Which trait alleles (disease) are dominent for color?

Black

7

What are two ways you can manage or select against a genetic abnormality?

1. Cross breeding
2. DNA test-cull carriers

8

Why is crossbreeding effective at eliminating the appearance of genetic abnormalities?

1) Recessive abnormalities-is not shown on carriers
2) Most only segregate in one breed

9

Why is selection for a simply inherited trait often easier than selection for a polygenic trait?

1) SI are only affected by a few genes
2) Polygenic are affected by environment factors such as diet

10

Which allele is dominant in Porcine Stress Syndrome?

Stress Resistent

11

Is the HYPP allele dominant?

Yes

12

Why are genetic abnormalities found more often in Angus cattle?

1) Largest registered breed in North America
2) Use of line breeding

13

T/F Genetic abnormalities are not segregating in some breeds.

False

14

How do genetic abnormalities commonly start appearing in the livestock industry?

Line breeding started many genetic abnormalities

15

The correlation coefficient measures two aspects of covariation. What are they?

Measures strength and direction between variables

16

The standard deviation of egg weight in chickens is 5 grams. What does this quantity mean?

The average deviation of the mean egg weight in this flock is 5 grams

17

Heritability is estimated by a ratio of what?

Variences

18

Genetic correlations are estimated by the calculation of what?

Correlation

19

Inbreeding coefficients are estimated by the calculation of what?

Correlation

20

Breeding values and progeny differences are estimated by what?

regression

21

Selection indicies are estimated by what?

Regression

22

Variance, standard deviation, correlation and regression all assume that the data follows what type of distribution?

Normal distribution

23

Explain why it is possible to completely eliminate a dominant allele from a population through selection but nearly impossible to remove a recessive allele, assuming DNA test does not exist.

1) You can differentiate carriers from a recessive carrier (phenotype)
2) When the frequency of the recessive gets really low in a herd most of those recessive alleles are found in heteros

24

T/F Inbreeding and crossbreeding will affect allele frequencies.

False

25

T/F Inbreeding and crossbreeding will affect genotype frequencies.

True

26

What does BV stand for?

Breeding Value

27

How is it possible for the true breeding value of an offspring to be greater than the average of the true breeding values of its parents?

Because of Mendallion Sampling

28

Why are additive gene effects transmitted to offspring yet gene combination values are not transmitted to offspring?

Because only one allele can be passed on. To pass on dominance both would have to be passed on

29

Seedstock producers are more interested in improving breeding values. Why?

They can be transmitted to the offspring and they want to sell genetics

30

Compare and Contrast Breeding Value with producing ability. Why are both of these used?

-Breeding Value-Genetic value as a parent, allows producers to make selection decisions
-Producing ability- Future performance predictor, allows for culling decisions to be made
-Both predict values of the animal

31

What is measured by the mean?

Average of the data sets

32

What is measured by the standard deviation?

The spread of the data but in units that are easier to interpret

33

What percent of a population would fall within one standard deviation from the mean

68%

34

What is measured by a regression coefficient?

Estimate the expected change in an observation per unit change in a second observation

35

Define Hardy Weinberg Equilibrium.

When no forces are acting to change allele frequencies. Alleles will not change