Animal Breeding and Genetics Final

Question 1

Selection

Answer 1

the practice of allowing certain individuals more opportunity to reproduce than others

Question 2

results of selection

Answer 2

are predictable in magnitude and direction
prediction only as good as the information used to make the prediction

Question 3

if the environment conditions have remained constant

Answer 3

the phenotypic change should mirror the genetic change

Question 4

response is a function of

Answer 4

heritability and the selectional differential

Question 5

sectional differential

Answer 5

the difference between the mean performance of the selected individuals and the avergae of the entire herd

Question 6

generation interval

Answer 6

the length of time it takes to replace the members of one generation in a herd

Question 7

average generation intervals - cattle

Answer 7

male - 3-4
female - 4.5-6

Question 8

average generation intervals - sheep

Answer 8

male - 2-3
female - 4-4.5

Question 9

average generation intervals - swine

Answer 9

male - 1.5-2
female - 1.5-3

Question 10

average generation intervals - horses

Answer 10

male - 8-12
female - 8-12

Question 11

average generation intervals - chickens

Answer 11

male - 1-1.5
female - 1-1.5

Question 12

an individuals phenotype is the result of its

Answer 12

genetic merit/breeding value and the effect of the environment

Question 13

What is the exception of an individual that gets half of its genetic make-up from each parent

Answer 13

a parent does not pass on the same genes to all offspring
mendelian smapling occurs and a random member of each gene pair ends up in each gamete

Question 14

the actual breeding value of an individual is

Answer 14

never known

Question 15

How can BV be estimated

Answer 15

an individuals preformance and the preformance of its relative
close relationships like progeny, sibs, and parents

Question 16

Addition of information from relatives

Answer 16

will always increase confidence in an estimate of breeding value

Question 17

accuracy

Answer 17

the confidence we have in an estimate of breeding value
correlation between the true breeding value and the estimated BV
values range from 0 to 1

Question 18

individuals own performance

Answer 18

single most important piece of information for estimating breeding value

Question 19

As heritability increases

Answer 19

EBV and Acc increases

Question 20

multiple records on an individual

Answer 20

some traits measured several times during an animal’s lifetime

Question 21

repeatability

Answer 21

is the associtation between successive records on an individual

Question 22

accuracy is always ________ for a ________ number of records when selection is based on multiple records for an individual

Answer 22

higher
larger

Question 23

increase is the most pronounced when

Answer 23

heritability and repeatability are both lower

Question 24

each additional record

Answer 24

adds to the accuracy but adds less than the previous record

Question 25

two reasons sibs may have similarities

Answer 25

same fraction of thier genes in common - full (1/2) and half (1/4)
frequently raised in similar circumstances - particularly true for full sibs, same maturnal environment, similar general health and food supply

Question 26

accuracy always

Answer 26

increases as n increases although less with each additional sib

Question 27

accuracy of using half sibs can never be

Answer 27

over 0.5

Question 28

in general…
sib info is -
sib info never -
should never -
should be used -

Answer 28

useful to estimate BV - carcass traits that cant be measured on the individual
results in really high accuracy - half sib info is limited to 0.5 or less, full sib info is freguently hampered by the environment
be used to replace an individuals own preformance record
to supplement the info on the individual

Question 29

progeny testing

Answer 29

one of the most powerful means of estimating breeding value

Question 30

as the number of progeny increases

Answer 30

accuracy increases

Question 31

accuracy is never

Answer 31

high when pedigree info is used

Question 32

pedigree info

Answer 32

should be used to supplement individual information

Question 33

tandem selection

Answer 33

only one trait is considered at a time
after it is improved sufficiently, another trait is considered by itself

Question 34

independent culling levels

Answer 34

all important traits are considered together
a minimum level of performance is established for each trait
any animal that does not meet the minimum for every trait is eliminated
animals that are deficient in one trait, but superior in all others will be culled

Question 35

selection index

Answer 35

most effecient procedure for improving several traits at once
takes into account hertabilities, genetic and phenotypic correlations, standard deviations, and economic values for all the traits
the trait being improved is economic merit

Question 36

what is marker assisted section tested on

Answer 36

hair
tissue
semen
blood samples

Question 37

traits that can get the most benefits from using MAS

Answer 37

1) have low heritability
2) are dificult and expensive to measure
3) cannot be measured until the animal is already contributed to the next generation
4) are currently not selected for as they are not rountinely measured
5) are genetically correlated with a trait that you do not want to increase

Question 38

igenity beef

Answer 38

for animals of angus, simmental, limousin, gelbvieh and herford descent
great for commercial breeders wishing to select better replacement heifers
the igenity beef profile provides 1 to 10 scores for 16 traits and 3 indexes

Question 39

igenity angus gold

Answer 39

for heifers that are 75% or more angus descent
great for commercial angus breeders to increase genetic gain within thier herds and profitability
comes with seeksire parentage analysis

Question 40

MAS is a

Answer 40

tool to increase accuracy of selection