AGI Test 4 Exam 2025 Questions
and Answers
Chapter 16 - ✔✔Mating Strategies Based on Animal Performance
Random & Assortative Mating - ✔✔- Random Mating: a mating system in which mates
are chosen at random
- Assortative Mating:
Positive Assortative Mating: mating "similar" individuals
Negative Assortative Mating: mating "dissimilar" individuals
Random Mating - ✔✔- Describes the manner in which individuals are paired for mating
- Random mating is sometimes confused with random selection (They are NOT the
same thing!)
- Random mating can be very helpful from the standpoint of genetic evaluation.
Positive Assortative Mating: - ✔✔- Mating the "best to the best." Males with the most
favorable BV are mated to females with the most favorable BV
- This causes bias in some genetic evaluations. BLUP is able to correct for assortative
mating
- Tends to create more genetic and phenotypic variation
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 1
,- Appropriate method when the goal is to change the mean performance of a population
Negative Assortative Mating - ✔✔- Mating the "best to the worst." Males with the most
favorable BV are mated to females with the least favorable BV
- Tends to decrease genetic and phenotypic variation
- Appropriate method when the goal is to reduce variation and select for an
intermediate optimum
Corrective Mating - ✔✔- A form of negative assortative mating
- A mating designed to correct in their progeny faults of one or both parents.
- Example: a sickle-hocked mare bred to a post-legged stallion
- In this case, neither individual is optimum, but the intent is to produce an
intermediate optimum in the progeny
Complementarity - ✔✔- An improvement in the overall performance of offspring
resulting from the mating of individuals with different but complementary breeding
values
- A corrective mating is an example of complementarity
Crossbreeding - ✔✔- Mating of a sire from one breed or breed combination to dams of
another breed or breed combination
Linecrossing - ✔✔- A line is a group of related animals within a breed.
- Mating of sire of one line or line combination to dams of another line or line
combination
Breed Complementarity - ✔✔- An improvement in the overall performance of crossbred
offspring resulting from crossing breeds of different, but complementary, biological
types
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 2
, Maternal Breed - ✔✔- A breed which excels in maternal traits
Maternal Trait - ✔✔- A trait especially important in breeding females
- Examples: fertility, freedom from dystocia, milk production, maintenance efficiency,
and mothering ability
Paternal Breed - ✔✔- A breed which excels in paternal traits
Paternal Traits - ✔✔- A trait especially important in market offspring
- Examples: Rate and efficiency of gain, meat quality, and carcass yield
Terminal Sire Crossbreeding System - ✔✔- A crossbreeding system in which maternal-
breed females are mated to paternal-breed sires to efficiently produce progeny that are
especially desirable from a market standpoint.
- All offspring are sold to slaughter
Terminal Sires - ✔✔- A paternal-breed sire used in a terminal sire crossbreeding system
Ch. 16 Summary - ✔✔- Random, positive assortative, and negative assortative are
mating techniques which may be used to help a breeder reach their goals
- Breed complementarity may be used to address any shortcomings that breeds may
have
- Breeds have been developed over time for different purposes. Crossbreeding
programs may be developed to take advantage of those differences
- Some breeds are known to excel for maternal traits while others excel for paternal
traits
- Crossbreeding systems may be used to take advantage of breed differences and
heterosis
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 3
and Answers
Chapter 16 - ✔✔Mating Strategies Based on Animal Performance
Random & Assortative Mating - ✔✔- Random Mating: a mating system in which mates
are chosen at random
- Assortative Mating:
Positive Assortative Mating: mating "similar" individuals
Negative Assortative Mating: mating "dissimilar" individuals
Random Mating - ✔✔- Describes the manner in which individuals are paired for mating
- Random mating is sometimes confused with random selection (They are NOT the
same thing!)
- Random mating can be very helpful from the standpoint of genetic evaluation.
Positive Assortative Mating: - ✔✔- Mating the "best to the best." Males with the most
favorable BV are mated to females with the most favorable BV
- This causes bias in some genetic evaluations. BLUP is able to correct for assortative
mating
- Tends to create more genetic and phenotypic variation
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 1
,- Appropriate method when the goal is to change the mean performance of a population
Negative Assortative Mating - ✔✔- Mating the "best to the worst." Males with the most
favorable BV are mated to females with the least favorable BV
- Tends to decrease genetic and phenotypic variation
- Appropriate method when the goal is to reduce variation and select for an
intermediate optimum
Corrective Mating - ✔✔- A form of negative assortative mating
- A mating designed to correct in their progeny faults of one or both parents.
- Example: a sickle-hocked mare bred to a post-legged stallion
- In this case, neither individual is optimum, but the intent is to produce an
intermediate optimum in the progeny
Complementarity - ✔✔- An improvement in the overall performance of offspring
resulting from the mating of individuals with different but complementary breeding
values
- A corrective mating is an example of complementarity
Crossbreeding - ✔✔- Mating of a sire from one breed or breed combination to dams of
another breed or breed combination
Linecrossing - ✔✔- A line is a group of related animals within a breed.
- Mating of sire of one line or line combination to dams of another line or line
combination
Breed Complementarity - ✔✔- An improvement in the overall performance of crossbred
offspring resulting from crossing breeds of different, but complementary, biological
types
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 2
, Maternal Breed - ✔✔- A breed which excels in maternal traits
Maternal Trait - ✔✔- A trait especially important in breeding females
- Examples: fertility, freedom from dystocia, milk production, maintenance efficiency,
and mothering ability
Paternal Breed - ✔✔- A breed which excels in paternal traits
Paternal Traits - ✔✔- A trait especially important in market offspring
- Examples: Rate and efficiency of gain, meat quality, and carcass yield
Terminal Sire Crossbreeding System - ✔✔- A crossbreeding system in which maternal-
breed females are mated to paternal-breed sires to efficiently produce progeny that are
especially desirable from a market standpoint.
- All offspring are sold to slaughter
Terminal Sires - ✔✔- A paternal-breed sire used in a terminal sire crossbreeding system
Ch. 16 Summary - ✔✔- Random, positive assortative, and negative assortative are
mating techniques which may be used to help a breeder reach their goals
- Breed complementarity may be used to address any shortcomings that breeds may
have
- Breeds have been developed over time for different purposes. Crossbreeding
programs may be developed to take advantage of those differences
- Some breeds are known to excel for maternal traits while others excel for paternal
traits
- Crossbreeding systems may be used to take advantage of breed differences and
heterosis
COPYRIGHT © 2025 BY OLIVIA WEST, ALL RIGHTS RESERVED 3
