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Evaluation Challenges

  • Genetic Evaluation of beef Cattle: Validation

 

While validation of national genetic evaluation is a practice very well developed and applied within the International Bull evaluations for dairy cattle (MACE), the situation is very different for the international bull evaluation of beef cattle (Interbeef). One major different between MACE and Interbeef evaluations is that Interbeef evaluations are carried out using raw performance data while MACE evaluations are based on national EBVs. Moreover, the beef industry does have its own peculiarities compared to the dairy industry:

 

  • Lower usage of artificial insemination: fewer “well-proven” bulls available within or across countries;
  • Smaller size of contemporary groups;
  • Wider use of multi-traits and multi-breeds evaluations;
  • Other traits more commonly used as predictors for the trait of evaluation;
  • Many traits are maternally influenced.

 

It is thus relevant to identify a suitable validation method that could work well for the beef evaluations. We will exploring the possibility to apply a modified version of some of the methodology currently applied in dairy, especially given the high interest of applying genomic evaluations in the beef evaluations as well.

 

 

  • Performance Recording and Genetic Evaluation: Harmonisation of traits

 

In the context of international genetic evaluations, the definition of the trait as recorded by the different countries does play a very important role. In the MACE evaluations, an important parameter to assess the similarities of trait definitions across countries is represented by the across country correlations.

 

 

From this point of view, correlations can be negatively affected if the definition of the traits evaluated differ too much from country to country. In this regard, trying to harmonise traits across countries is an important exercise that can result in stronger correlations and, thus, more accurate evaluations.

During 2021/2022, a study on the harmonisation of calving traits was carried out at Interbull Centre and resulted in a set of recommendations. These have been made available to countries, and included in an update to the ICAR guidelines. The update to the guidelines were submitted to the ICAR Board for approval in September 2022.

The work initiated with calving will continue further in order to deliver a set of recommendations valid also for the other internationally evaluated traits.

 

Further information on the topic can be found here:

 

Presentation at the Interbull Open Meeting, Montreal, 2022

 

Recommendations on the harmonisation of Calving Traits

 

  • Genomic Evaluation of Dairy Cattle: Genomic Reliabilities

 

Genomic reliabilities (GREL) are less comparable across countries than conventional reliabilities. It is important that the GREL are consistent with the conventional REL. For this reason, we aim to develop standard procedures for GREL calculations for national genomic evaluations. The methodology developed is now also applicable to Single Step model for test day traits. The genomic reliabilities from Single Step models are now consistent between genotyped and not-genotyped groups when compared to a multiple step model. The GREL software has also been improved in its efficiency in relation to computational time which makes it possible to use all SNPs.

As the polygenic effect is not properly accounted for in the calculation process, the scaling effect of genomic reliabilities is still being investigated. It will be important to assess if the final adjustment procedure could still be considerate accurate enough. The effect of percentage of SNPs used for calculating genomic reliabilities should also be investigated further.

 

Further information on the topic can be found here:

 

Technical document on derivation and application of adjustment factors for genomic reliabilities

 

Supplementary document

 

  • Genomic Evaluation of Dairy Cattle: Genomic pre-selection

 

With the spreading of genomic evaluations introduced by an increasing number of countries, national genetic evaluations’ results, and therefore also international results, have started accumulating a new source of bias due to genomic pre-selection. The amount of this bias varies from country to country, depending on the level of pre-selection applied. Interbull aims to identify the best way to account for the different level of genomic pre-selection from countries and, consecutively, on developing a new MACE software able to properly model it.

 

Further information on the topic can be found here:

 

Interbull Open Meeting, Montreal 2022:

 

 

 

 

  • Genetic and Genomic Evaluation of Dairy cattle: Trend Validation

 

With the onset of genomic validations and the accumulation of genomic pre-selection in the national genetic evaluations’ results, it was necessary to review the validation methodologies in use, so to make them able to better detect traces of genomic pre-selection. This is expected to result in the creation of new GEBVtest software in order to overcome the known concerns related to the current available software which are:

 

  • Arbitrary of de-regressed method applied by countries
  • Base of expression in reduced and full data can be different
  • Both EBV and dEBV can carry genomic pre-selection’s bias.

 

The new software will be enhanced with the following features:

 

  • Adjustment of base of expression between reduced and full data
  • Use of GEBV and dGEBV instead of EBV and dEBV as they can be biased

 

Further information on the topic can be found here:

 

Interbull Online Meeting 2021

Useful deadlines
2022-12-12
Useful deadlines for the January 2023 test run Read more...

SAVE THE DAY!
2022-11-25
Interbull is organizing a technical workshop in February 2023 Read more...

Interbull Centre - Department of Animal Breeding and Genetics, SLU - Box 7023, S-75007 Uppsala, Sweden - interbull@slu.se

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