Selection Systems Flashcards

1
Q

who is selected

A

individuals
relative - ancestors, siblings and progeny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how are they selected

A

independent culling levels
tandem selection
index of weighted traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are correction factors?

A

sex
age of dam
age of calf
singleton vs twin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is individual selection based on

A

animals own performance
practicle if trait is measurable and expressed early

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is ancestral selection based on

A

weighted average of ancestors
father counts more then grandfather
useful if trait is not expressed early

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

when do you use ancestral selection

A
  • when individual is not available
  • use at least one relative on both the dam and sire side of the pedigree (same relatives for each individual)
  • use closest relative available
    use mean of relatives if theres many records
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the genetic selection of a horse

A

long generation
few offspring
late mating
training is a cofounding factos
improvement is slow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is genetic selection for dogs and cats

A

obedience tests
traiing is also a confounding factor
ancestral selection
progeny or sub selection (littler success, breeders should maintain contact and follow up)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how is selection typically done?

A

need to select for more than one trait
negative traits doesnt mean detrimental and positive doesnt mean bene ficial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how does genetic correlation effect meat quality?

A

marbling score and backfat thickness, lean yeild and shear force
marbling is good the more abundent the better

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are independent culling levels

A

select for minimum value per characteristic, no averaging
useful for multipurpose animal
potentially cull many animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is ROP bulls?

A

record of performance
30 cm scrotal circumference
pass on feet and legs
above average weight gain for breed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how do you choose to rebreed a cow in the herd?

A

they must produce a calf
must mother well to that calf
must not be dangerous (have temperament problems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is tandem selection?

A

seelcting for most important trait this season and second most important trait next season

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

when is tandem selection efficient ?

A

if all desired traits are positively correlated
BUT- in reality used primarily as a temporary selection to focus on the most important trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is index selection?

A

use a formula to simultaneously select for several traits, emphasizing some more than others

17
Q

what is indirect selection?

A

use of a correlated trait to select for another trait

18
Q

When is indirect selection useful?

A

traits that are difficult to measure
traits with low hieratability but high relevancy

19
Q

What does response to selection depend on?

A

generation interval
selection intensity
variation in population
hieratability of trait
accuracy of selection
effective population size

20
Q

what is generation interval?

A

average time in years between when an animal and its replacement are born
affected by: gestation length, age at puberty and like sex replacement

21
Q

what is selection intensity

A

average proportion of animal selected
fewer males kept then females
smaller proportion of litter bearers
based on animals kept - expressed as a standard deviation

22
Q

what is variation selection diferences

A

change in lb, litter size
its a selection group vs the total group

23
Q

what is hieretability?

A

the likelyhood of offspring developing a trait from parentage

24
Q

what is accuracy of selection?

A

ranges from 0-1 and depends on
method of selection and number of measurements

25
what is effective population size
must be large enough to avoid inbreeding ans to maintain variation for selection
26
what is genetic gain?
genetic improvement over time
27
how do you increase genetic gain
increased selection intensity (select fewer but it may decrease genetic variety) increase accuracy of selection(use individuals instead of pedigree) increase genetic variation - introduce new quality stock decrease generation interval - harvesting embryos = very expensive
28
what is compare to contemporaries
doesnt really measure improvement does assess position in industry see how past animal test and then see how many animals in total have the genetic progress
29
what is improvement over time
compare offsprings performance to parents compare herds performance over many years
30
what is a repeat mating design
compare new bull to old bull - breed young females with old bull and old females with young bulls transport stored emyros and fresh embryos in one season compare performance of calves
31
what happens if there is no progress
you hit a plateau that is the peak of that progress now it cant grow without serious fertility problems
32