Term
| Direct Response to Selection |
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Definition
| genetic change in a trait resulting from selection of that trait |
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Term
| Correlated Response to Selection |
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Definition
| genetic change in one or more traits resulting from selection in another |
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Term
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Definition
| how closely genes are located on the chromosome |
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Term
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Definition
| a phenomenon of a single gene affecting more than one trait |
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Term
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Definition
| 2 causes of correlated response to selection: |
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Term
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Definition
| measure of strength of the relationship between the phenotypic value in one trait and the phenotypic value in another trait |
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Term
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Definition
| measure of strength of the relationship between the BV in one trait and the BV in another trait |
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Term
| Environmental Correlation |
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Definition
| measure of strength of the relationship between the environmental values in one trait and the environmental values in another trait |
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Term
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Definition
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Term
1. Factors that affect a response to a trait that you are directly selecting for
2. Genetic correlation between traits X and Y
3. Genetic variation in the correlated trait |
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Definition
| Factors that affect correlated response |
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Term
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Definition
| selection for a trait as a means for improving that same trait |
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Term
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Definition
| selection for one trait as a means of improving a genetically correlated trait |
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Term
1. Difficult/Expensive to measure traits
2. Greater accuracy in a correlated trait
3. Indicator Traits |
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Definition
| Why should we use indirect selection? |
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Term
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Definition
| a trait that may or may not be important in itself, but is selected for as a way of improving some other genetically correlated trait |
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Term
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Definition
| selection pressure placed on only one trait (may result in correlated response) |
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Term
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Definition
placing direct selection pressure on more than one trait
- must use EBV |
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Term
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Definition
| a value that represents an individuals genetic merit across more than one trait |
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Term
| 1. Tandem Selection 2. Independent Culling Levels 3. Selection Index |
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Definition
| 3 General Methods of Net Merit |
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Term
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Definition
| selection for one trait for a period of time followed by selection for a second trait |
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Term
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Definition
| a level of breeding value that is considered optimal |
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Term
1. Only successful when traits are "favorably" correlated
2. Genetic correlations make it impossible to maintain a trait at its optimal level |
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Definition
| Disadvantages of Tandem Selection |
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Term
| allows producers to be flexible and quickly respond to changing market needs |
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Definition
| Advantage of Tandem Selection |
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Term
| Unfavorable Genetic Correlation |
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Definition
| improvement in one trait results in poorer performance in another trait |
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Term
| Favorable Genetic Correlation |
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Definition
| improvement in one trait results in improvement in another trait |
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Term
| Independent Culling Levels |
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Definition
minimum standards for traits undergoing multiple trait selection
- animals failing to meet any one standard are rejected regardless of merit in other traits |
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Term
1. Simultaneous selection (as opposed to tandem selection)
2. Convenient for selection at different stages of the animal's life
3. Saves money by eliminating rejects early on |
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Definition
| Advantages of Independent Culling Levels |
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Term
1. How do we determine culling levels?
a. if levels are too strict, may not have enough breeders
b. if levels are not strict enough, you will not make as
much genetic progress
2. Potential to exclude really good animals because they are not within the guidelines of a different trait |
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Definition
| Disadvantages of Independent Culling Levels |
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Term
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Definition
an index or combination of weighing factors and genetic information on more than one trait
- used to predict an aggregate breeding value |
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Term
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Definition
| the change in profit expected for a unit change in each of the traits |
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Term
1. Fastest, most efficient way to improve multiple traits
2. Balance superiority in one trait versus inferiority in another trait
3. The index clearly lays out traits and economic weightings of importance |
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Definition
| Advantages of Economic Selection Index |
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Term
1. How do you determine the economic weightings?
2. Economic weights change over time
3. Assigns a single value to an animal that has many characterstics |
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Definition
| Disadvantages of Economic Selection Index |
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Term
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Definition
the mating of relatives
- parents share a common ancestor |
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Term
1. Fixing favorable alleles
2. Uniformity
3. Create opportunity for hybrid vigor (heterosis) |
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Definition
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Term
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Definition
| the mating of individuals within a particular line; a mating system designed to maintain a substantial degree of relationship to a highly regarded ancestor or group |
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Term
1. Increase heterozygosity
2 Increase genetic varience
3. Decrease uniformity |
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Definition
| Reasons to Outbreed (Cross-breed) |
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Term
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Definition
| the mating of unrelated individuals |
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Term
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Definition
| an increase in the performance of hybrids over that of purebreds |
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Term
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Definition
a measure of the level of inbreeding in an individual
- the probability that both genes of a pair are identical by decent (IBD)
- the probable proportion of an individual's loci containing genes that are identical by descent |
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Term
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Definition
| genes that are copies of a single ancestral gene |
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Term
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Definition
| Inbreeding and Relationship Coefficient Range |
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Term
1. Formula
2. Path Method
3. Tabular Method |
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Definition
| 3 Methods to Calculate Inbreeding/Relationship Coefficient |
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Term
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Definition
| a method for calculating inbreeding and relationship coefficients that simulates the paths taken by identical genes as they flow from ancestor to ancestor |
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Term
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Definition
| a method for calculating inbreeding and relationship coefficients involving construction and updating of a table (Relationship Matrix) relating all members of a population |
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Term
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Definition
| the population of animals whose parents are either unknown or ignored (typically the animals at the beginning of the pedigree) |
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Term
| BLUP and Large-Scale Genetic Evaluation |
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Definition
| Additional Methods to Calculate R(x,y) and F(x) |
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Term
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Definition
| the increased homozygosity and expression of unfavorable recessive alleles caused by inbreeding |
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Term
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Definition
| effect of an individual's genes on its performance |
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Term
| Maternal Genetic Component |
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Definition
| the effect of the genes in the dam that influence the performance of the individual through the environment provided by the dam |
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Term
| Paternal Genetic Component |
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Definition
| the effect of the genes in the sire that influence the performance of the individual through the environment provided by the sire |
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Term
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Definition
| hybrid vigor for the direct component of a trait |
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Term
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Definition
| hybrid vigor for the maternal component of a trait |
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Term
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Definition
| hybrid vigor for the paternal component of a trait |
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Term
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Definition
the amount of hybrid vigor that is attainable in the first-cross individuals
- the maximum amount of attainable HV |
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Term
| Retained Hybrid Vigor (Retained Heterosis) |
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Definition
| hybrid vigor remaining in later generations of hybrids (after the F1 generations) |
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Term
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Definition
| hybrids designed to retain hybrid vigor without crossbreeding |
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Term
1. Merit of component breeds
2. Hybrid vigor
3. Breed complementarity
4. Consistency of performance
5. Replacement considerations
6. Simplicity
7. Accuracy of genetic prediction |
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Definition
| Ways to Evaluate Crossbreeding Systems |
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Term
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Definition
| the mating of a hybrid to a purebred of a parent breed or line |
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Term
| Sire x Dam Complementarity |
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Definition
| mating sires strong in paternal traits to dams strong in maternal traits |
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Term
| Rotational Crossbreeding System |
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Definition
| a crossbreeding system in which generations of females are "rotated" among sire breeds in such a way that they are mated to sires whose breed composition is most different form their own |
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Term
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Definition
| a rotational crossbreeding system in which all sire breeds are used simutaneously |
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Term
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Definition
| %Retained Hybrid Vigor of a 2-way rotation using purebreds |
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Term
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Definition
| %Retained Hybrid Vigor of a 2-way rotation using crossbreds |
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Term
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Definition
| %Retained Hybrid Vigor of a 3-way rotation using purebreds |
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Term
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Definition
| %Retained Hybrid Vigor of a 3-way rotation using crossbreds |
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Term
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Definition
a rotational crossbreeding system in which sire breeds are not used simultaneously but are introduced in sequence
-reduced hybrid vigor due to backcrossing
-easier to manage; only one breeding site required |
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Term
| Terminal Crossbreeding System |
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Definition
| a crossbreeding system in which maternal-breed females are mated to paternal breed sires (terminal breeds) to efficiently produce progeny that are desirable from a market standpoint |
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Term
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Definition
| terminal sire crossbreeding system in which replacement females are either purchased or produced from separate purebred population within the system |
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Term
| Rotational/Terminal System (Rota-Terminal) |
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Definition
| a crossbreeding system combining a maternal rotation for producing replacement females with terminal sires for producing market offspring |
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Term
| Composite Synthetic Animals |
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Definition
a hybrid animal with at least two breeds in its background
-bred to their own kind |
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