Mating Strategies and Heterosis Flashcards
Define crossbreeding.
Mating of individuals from different breeds or lines
What are the four benefits/advantages of crossbreeding?
- complementarity
- migration of new genotypes
- synthetic (composite) breeds
- rapid change in performance
Are heterosis and hybrid vigor the same?
Yes!!
Define heterosis/hybrid vigor.
The increase in the performance of crosses (hybrids) between diverse parents such that the progeny is superior to the parent average.
What are the three mechanisms of heterosis?
- dominance
- overdominance
- epistasis
True or False. Heterosis can be inherited.
False!
From the breeding equation, what part contributes to heterosis?
GCV
Which gains more from heterosis? Carcass or reproductive traits?
Overall, low heritable traits have great heterosis. As Reproductive traits are lowly heritable, they have a higher heterosis.
Define Reciprocal Cross
A pair of crosses between a male of one breed and a female of another breed, and vice versa.
What are the three types of heterosis?
- maternal
- paternal
- individual
True or False. If the parents are purebred, they will have maternal and paternal effects on the offspring.
False
Define individual heterosis.
The advantage of the crossbred individual relative to the average of the purebred individuals.
Define Heterosis Retention.
Heterosis remaining in generations after F1.
When is heterosis maximized?
In F1 crosses.
Define mating decisions.
Which male breeds to which female.
Define mating system.
Set of rules for making mating decisions.
What are the two criteria of a mating system?
Animal Performance and Pedigree Relationship
What are the three strategies under Animal Performance?
- random mating
- assortative mating
- combination of strategies
What are the three strategies under Pedigree Relationship?
- Inbreeding
- Linebreeding
- Outbreeding/Crossbreeding
Does Random Mating have anything to do with selection?
NO!
Define Positive Assortative Mating.
Mating between similar phenotypes.
Define Negative Assortative Mating.
Mating between different phenotypes.
Define complementarity.
Improvement of the overall performance of offspring resulting from the mating of individuals with different but complementary breeding values.
Define inbreeding.
Mating of individuals more closely related than average for the population.
What is the positive effect of inbreeding?
prepotency
Define prepotency
The ability of an individual to stamp its characteristic (similar performance) on its offspring to such an extent that they resemble their parents more closely than usual.
What is negative of inbreeding?
- increase in homozygosity = decrease in variation
- inbreeding depression
Define inbreeding depression.
Decreased performance of inbred animals due to unfavorable recessive alleles. Result of poor GCV.
What is an acceptable rate of inbreeding?
0.5 - 1%
Define corrective matings
Matings designed to correct in their progeny faults of one or both parents
