Principles of Selection

Question 1

is the art and science of the genetic improvement of farm animals.

Answer 1

Animal Breeding

Question 2

choosing some animals as parents of the next generation of animals.

Answer 2

Selection

Question 3

removal of inferior animals

Answer 3

Culling

Question 4

What is the basis of animal breeding is ?

Answer 4

correct selection of breeding animals for mating

Question 5

obtained as a regression of a phenotypic deviation

Answer 5

Estimation of Breeding Value

Question 6

records deviated from a mean

Answer 6

Phenotypic Deviation

Question 7

Breeding Value in the phenotypic deviations

Answer 7

Regression

Question 8

is the proportion of the phenotypic variance that is due to genetic effects including additive, dominance and epistasis:

Answer 8

Heritability in the broad sense (H2)

Question 9

is the proportion of the phenotypic variance that is due to additive genetic effects only.

Answer 9

Heritability in the Narrow Sense (h2)

Question 10

What does the heritability in the narrow sense measure?

It measures the degree to which the offspring —-

If a trait has a large heritability, animals with high performance for the trait will produce offspring with —- ———

Answer 10

resemble their parents in performance for a trait.

High Performance

If a trait has a small heritability, performance records of parents reveal —— —— about the performance of their offspring

Question 11

Traits with low heritability ranges from??

Answer 11

h2 < 0.20

Question 12

Moderately heritable traits ranges from ??

Answer 12

h2 0.2 to 0.4

Question 13

Highly heritable traits ranges from?

Answer 13

h2 > 0.40

Question 14

Traits with low heritability (h2 < 0.20): charactersitics:

Answer 14

• reproductive traits

• longevity or productive live ( about 0.10)

Question 15

Moderately heritable traits (h2 of 0.2 to 0.4): Characteristics: ll

Answer 15

• Milk yield, fat yield and protein yield (0.25-0.35)
• Birth weight
• Weaning weight
• Yearling weight

Question 16

Highly heritable traits (h2> 0.4):

Characteristics:

Answer 16

• Carcass traits and traits related to skeletal dimensions like mature body weight

• Fat and protein% in milk.

Question 17

animals are selected based on their ancestors, where the performance of these ancestors is known then a useful selection can often be made.

Answer 17

Pedigree Selection

Question 18

the breeding value of each individual is assessed on the average performance of a random sample of its progeny, and animals are selected or culled based on this progeny performance

Answer 18

Progeny Testing

Question 19

any animals unsatisfactorily for the character being selectedcan be culled before breeding is commenced.

Answer 19

Mass or Individual Selection

Question 20

selection based on theperformance of nearby relatives

Answer 20

Family Selection

Question 21

selection is made for one trait or character at a timeuntil it is improved, then for a second trait and so on.

Answer 21

Tandem Selection

Question 22

a method where minimum standards of performanceare established for each trait in the criteria. Anyanimal not satisfying the minimum standard for alltraits is culled.

Answer 22

Independent Culling Level

Question 23

Each character is given a score and scores for all characters being considered are added together. Those with the poorest total scores would be culled.

Answer 23

Selection Index

Question 24

breeding of two or more different breed of animal.

Answer 24

Crossbreeding

Question 25

means that breeding of animal with the same breed.

Answer 25

Purebreeding

Question 26

Mating between animals, which are more closely related to each other than the average relationship between all individuals in the population.

Answer 26

Inbreeding

Question 27

1st mating: A x B 1st generation: ½ A ½ B 2nd mating A x ½ A ½ B 2nd generation ¾ A ¼ B

Answer 27

Inbreeding

Question 28

Mild form of inbreeding. Mating of cousins, grandparent to grand offspring or half-brother to half sister.

Answer 28

Linebreeding

Question 29

Example: A is ♀; B & C is ♂ 1st mating: A x B A x C 1st generation: ½ A ½ B ½ A ½ C 2nd mating ½ A ½ B x ½ A ½ C 2nd generation ½ A ¼ B ¼ C

Answer 29

Linebreeding

Question 30

Mating of animals of different families within the same breed that are not closely related. (For at least the first four to six generation.

Answer 30

Outcrossing

Question 31

is the mating of two animals from different breeds.

Answer 31

Crossbreeding

Question 32

The increased level of performance of the offspring as to compare to the average of the parental type is known as

Answer 32

Heterosis or Hybrid Vigor

Question 33

There is a -------- relationship between heterosis and heritability: the traits that demonstrate the most hybrid vigor are those that show the ------- heritability.

Answer 33

Reciprocal Lowest heritability

Question 34

Crossbreeding can be used to:

Answer 34

•Develop new breeds •Upgrade local breeds

Question 35

Two different populations can be crossed with each other to produce an F1 generation which is used only for production purposes and not for breeding.

Answer 35

Single Two-Way Cross

Question 36

This system relies on the crossing of two breeds A and B to produce a female excelling in maternal performance in a particular environment and the use of a third breed to produced the ideal animal for the market product.

Answer 36

Three Way Cross

Question 37

Populations A and B are first crossedwith each other, and so are C and D to obtain the F1generation A x B and C x D. These are then crossedtogether to produce the double hybrids AB x CD. It isnecessary to maintain only relatively small number ofanimals of the lines A, B, C, and D.

Answer 37

Four way cross

Question 38

The F1 females are back crossed to oneof the parental populations. For example, A x B females are mated with A or B to produce an offspring AB x A or AB x B.

Answer 38

Backcross

Question 39

This method takes fulladvantage of heterosis in the F1 females and half ofthe potential heterosis in the offspring.

Answer 39

Backcross

Question 40

In which males of each of the two breeds involved are used alternately; this system hasthe advantages over the two-way cross, in that thecrossbreed females can be used for breeding.

Answer 40

Two-way rotational cross

Question 41

A x B ------ AB First mating : A x AB Second mating: B x AB Third mating: A x AB

Answer 41

Two-way rotational cross

Question 42

In which males of each of the three breeds are used in turn; cross bred females produced can be used for breeding.

Answer 42

Three-way rotational cross

Question 43

A x B x C ------- ABC First mating : A x ABC Second mating: B x ABC Third mating: C x ABC

Answer 43

Three way rotational cross

Question 44

Selection for Quantitative Traits

Answer 44

Estimate merit (BV's) Determine accuracy of estimation Predict response to selection

Question 45

Methods of Selection

Answer 45

Tandem Selection Independent Culling Level Selection Index

Question 46

Aids to Selection

Answer 46

Pedigree Selection Progeny testing Mass or Individual Selection Family Selection

Question 47

Mating Systems

Answer 47

Cross breeding and Purebreeding

Question 48

Types of Crossbreeding

Answer 48

Inbreeding Linebreeding Outcrossing

Question 49

Methods of Crossbreedings

Answer 49

Single two way Crosses Three way cross Four way cross Back cross Two way rotational cross Three way rotational cross