Selection programs

Question 1

an estimate of the genetic value of an animal as a potential parent of the next generation

Answer 1

estimated breeding value

Question 2

used to compute EBV

(non-acronym answer)

bonus: meaning of EBV

Answer 2

Best Linear Unbiased Prediction (BLUP)

bonus: estimated breeding value

Question 3

what are accounted and unaccounted for in statistical models used to describe traits of interest

Answer 3

• accounts for and separates out factors that influence animal’s performance in order to better estimate an animal’s genetic value
• pedigree of animals involved

Question 4

what is an animal model?

Answer 4

a statistical model estimating an animal’s genetic value which also includes the pedigree of all the animals

Question 5

balances information on the performance of an animal compared to others in the same herd with the performance of its relatives in the same and other herds

Answer 5

estimated breeding values

Question 6

___________ inherit half of their genes from the male parent and half from the female parents

Answer 6

progeny

Question 7

the expected genetic merit of a progeny for a trait depends on what?

Answer 7

half of the EPV of the male parent and half of the EPV of the female parents

Question 8

expected performance of a progeny in an average environment

Answer 8

expected genetic merit of a progeny

Question 9

Other than EBV, what can be also calculated? (non-acronym answer)

Answer 9

Estimated Progeny Differences (EPD)

Question 10

• EPD is equal to half of an EPV
• the expected performance of a progeny in an average environment is the sum of the EPD of the male parent and the EPD of the female parent

provide the equation for the expected performance of a progeny in an average environment using only estimated breeding values

Answer 10

EPV of progeny = 1/2 EPV of male parent + 1/2 EPV of female parent

Question 11

process of choosing animals to be the parents of the next generation

Answer 11

selection

Question 12

tools for selecting animals (expand)

bonus: why

Answer 12

Estimated Breeding Values (EPV) and Estimated Progeny Differences (EPD)

bonus: provides estimates of the genetic value of the animal and provides the farm manager with an estimate of how well the offspring of that animal should perform

Question 13

selection should be based on what?

bonus: why?

Answer 13

selection criteria

bonus: so the process is focused on a particular goal

Question 14

opposite of selection

bonus: give the definition

Answer 14

culling

bonus: removed from the herd and not allowed to breed

Question 15

True or False:
culling is most often applied to breeding males

bonus: why?

Answer 15

false, most often applied to breeding females

bonus: females are culled from breeding herd due to poor reproductive performance, injury, poor genetic qualities, and old age

Question 16

which is more expensive: male or female?

Answer 16

male, because it is the scope of genetic improvement

Question 17

the number of replacement females that are kept

bonus: what is meant by replacement?

Answer 17

replacement rate

bonus: purchased

Question 18

_______________ is the number of females that are removed from the herd

Answer 18

culling rate

Question 19

differentiate replacement rate and culling rate

Answer 19

• both are used in livestock production systems with continuous turrnover of breeding females; balancing selection of young females to replace breeding females which are to be culled

replacement rate
- number of replacement females that are kept

culling rate
- number of females that are removed from the herd

Question 20

Good target level for replacement level?

Answer 20

30 - 40% for pigs and dairy cattle and lower than that for sheep and beef cattle

Question 21

When old breeding females are culled and removed from the herd, they are replaced with young females that have _______________

bonus: why?

Answer 21

a higher EBV

bonus: with continuous genetic improvement, the new generation is expected to have a higher EBV than previous generations

Question 22

results from the various forms of selection

Answer 22

genetic progress

Question 23

how is genetic progress measured?

Answer 23

the average of EBVs or a herd or whole population over time

Question 24

measured by the average of EBVs or a herd or whole population over time

Answer 24

genetic progress

Question 25

what factors influence genetic progress?

Answer 25

• selection intensity
• heritability
• generation interval

Question 26

what does it mean to select more intensely?

bonus: why?

Answer 26

selecting fewer but better animals

bonus: to give better genetic progress

Question 27

True or False:
females can be selected much more intensely than males

bonus: why?

Answer 27

False, males selected more intensely

bonus: because male can mate with any females and so fewer males are needed than females

Question 28

traits with higher heritability have more (more / less) genetic variation and are (easier / harder) to improve

Answer 28

higher heritability = more genetic variation = easier to improve

Question 29

explain how generation interval affect genetic progress

Answer 29

the faster the turnover rate of the herd, the higher the replacement rate and the shorter the generation interval; inversely, the longer the generation interval, the slower the genetic progress

Question 30

modified true or false:
the factors affecting genetic progress always interact positively

bonus: what are these factors?

Answer 30

false, factors affecting genetic progress sometimes interact negatively

bonus:
- selection intensity
- heritability
- generation interval

Question 31

refers to the length of time it takes on individual to be replaced by one of its offspring

Answer 31

generation interval

Question 32

why does genetic progress differ between breeds and species?

Answer 32

due to differences in biology