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Flashcards in Exam 4 Deck (27):
1

Heritability can be defined as a ratio of what two variance components?

BV and Phenotype

2

Repeatability can be defined as a ratio of what two variance components?

Phenotype and Producing ability

3

Give an example of a trait with low, moderate and high heritability.

Low-Fertility
Moderate-Milk Yield
High- Marbling

4

List two ways to increase heritability and repeatability. How would this benefit a producer?

1) treat all animals the same way
2) record more data on individual animals
This helps improve selection accuracy

5

What range of values is possible for heredity?

0-1

6

Define contemporary group.

A group of animals of the same gender, about the same age and managed the same way

7

Define heritability.

Regression BV on P

8

What is an important use for heritability?

Makes selection decisions for traits

9

Why does the regression coefficient increase as the number of records increase?

It decreases environmental variation

10

What is the essential principle involved in the several approaches to increasing heritability and repeatability?

Decrease environmental variation

11

Why do we use adjustment factors?

Increase accuracy of breeding value predictions

12

Heritability as regression coefficient looks like?

h^2= cov(P,BV)
-------------
6^2p

13

Heritability as a correlation coefficient looks like?

h^2= cov (BV,P)
-------------
6BV 6P

14

In what region of the graph are true breeding values under estimated?

Above the line

15

Explain why heritability for a trait is not always constant among different groups.

1) Genetic variation of BV
2) Environmental variation

16

Why should producers use contemporary groups when possible?

Increase accuracy for BV predictibility

17

Why would livestock producers calculate ratios of trait values?

Easier to tell which animals are above or below average for a trait

18

Provide one reason why data on all producers animals should be reported to breed associations.

Increase accuracy

19

What are the four factors that affect genetic gain in a herd or breed?

Selection Intensity
Selection accuracy
Genetic interval
Genetic Variation

20

Why is the two path version of the genetic change equation usually more appropriate than the one path version? Why?

1) Two path accounts for selection accuracy
2) Selection intensity
3) Generational interval
Different between male and female

21

What quality in genetic change equation is measured by the correlation between true breeding vales and estimated breeding values?

Selection accuracy

22

With truncation selection, the selection intensity can be found found in a table. what piece of information is needed to find appropriate selection intensity?

% animals kept as replacements

23

List two tradeoffs of the key equation.

1) Selection accuracy and genetic interval increase together
2) Selection intensity and generational interval increase together

24

List three ways that can be used to increase accuracy of a breeding value.

1) Increase Heritability
2) DNA test
3) # of records

25

What are 2 general methods for predicting breeding values?

Animals performance
DNA testing

26

What does is mean when we say the EBV is unbiased?

The estimate could go in a favorable or unfavorable way

27

Why is BLUP more commonly used in breed associations?

1) Genetic trends
2) Contemporary groups
3) Non random breeding