Evaluation of the breeding program

22 important questions on Evaluation of the breeding program

What is, apart from genetic progress that has been achieved, another important aspect that needs to be evaluated in breeding programs?

To what extend has the genetic diversity been maintained

How is it possible to get a good approximation of the genetic improvement accross generation?

By estimating the EBV with high accuracy and using BLUP

Why is it covenient in livestock to look at the average EBV per birth year rather than per generation?

Often generation intervals are not equal in both sexes and generations are overlapping rather than discrete
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What exactly requires evaluation in the EBV?

The difference between the realsied and predicted response?

How can realised genetic improvement be determined?

By taking the diference in average EBV, for example between generations or birth years

What is a genetic trend?

A compilation of average EBV per birth yea, and indicates the diection of change across birth years

What if there is an incease in EBV?

indicates a possitive genetic trend. Animals genetically improved across birth years, so selection has been sucessfull

What do you do when the realized genetic response deviates substantially from the predicted genetic response?

It is important to assess the assumptions with respect to selection intensity, accuracy, additive genetic standard deviation and generation interval are met

What can be a reason for not meeting the expected response to selection?

The population is reaching the selection limit

What are the main reasons for the occurence of a selection limit?

- Loss of genetic diversity
- Opposing natural selection through reduced ferility or oven mortality
- Limiting environment to express potential

What can be reasons for deviations from expected genetic trend?

May be due to a change in breeding goal or a change in phenotype recording

What is genotype by environment (GxE)?

When the ifference in performance of thwo genetypes depends on the environment in which the performance is measured

What is the reaction norm?

- Teh slote of the reactio norm will tell you how sensitive the genotype is

What does a reaction norm represent?

A reaction norm represents performance of genotypes in a range of environments

What do non-prallel reaction norms of genoypes indicate?

Indicates the presence of genotype by environment interaction

What do two environments require?

Seperate breeding programs if the correlation between performance in both environments is smaller than 0.6

What is a reason for correlation?

That the genes that are involved in the correlated trait are involved in the trait under selection

What is a pleiotropic effect of a gene?

A genetic correlation can also exist because the gene affecting the trait is influencing another trait as well

What are the reasons for genetic correlation to excist?

- Linkage disequilibrium
- Pleiotropic effect
- Conflicting resource allocation

What is the cost of avoiding correlated responses?

Lower genetic response in the main traits under selection

Where does multi-trait selection to avoud undesirable correlated responses lead to?

Leads to lower genetic respons for one traitcompared to single-trait selection

What is also important in predicting the future?

You have to respect limits (legislation) and opportunities (market expansion) and adjust your breeding program accordingly

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