Interbull genetic evaluations for production traits - Test-run evaluation schedule

At the October 12, 1998, meeting of the Steering Committee of Interbull, it was decided to continue with biannual test-run evaluations for production traits.

Test-run evaluations intend to investigate the impact of new or modified national genetic evaluation results on the international evaluation; also to investigate potential improvements of the international genetic evaluation procedure. Results of such test-runs are reviewed by technical representatives of all countries involved. Pending on this review, changes are incorporated in the following routine evaluation.

Starting in 2010, test-runs will be conducted in January and September at the Interbull Centre.

The test-run of January intends to investigate changes with the view to introduce them in the April routine evaluation of the same year.

The test-run of September intends to investigate changes with the view to introduce them in the December routine evaluation of the same year.

More in general, partecipation in a test evaluation run with modified data implies that an official implementation of the modification is targeted for a near future, usually within 6 months.

Participating countries are requested to consider potential changes/modifications of their national genetic evaluation procedure in line with the above-mentioned time schedule.

Guideline for assessing the necessity of a test-run

Changes in models for genetic parameter and breeding value estimation and modification of preadjustment factors, such as age, require new validation according to the established procedure and a test-run before acceptance to a routine international evaluation.

Frequently countries introduce changes in their system with only minor effect on the national bull ranking. Such changes, however, may have considerable impact on international evaluations.One way to assess this would be to estimate the within-country sire variance with the procedure currently used by Interbull. Large changes of this parameter are invariably associated with substantial re-ranking in the international list.

Experience shows that changes in sire variance estimates (based on data included in the international evaluation) larger than 5% from one evaluation to the next can not be explained by added information from young bulls. In such case, trend validations and a test-run will be required.