INTERBULL Routine Genetic Evaluation for Dairy Production Traits

August 1998

Introduction

The ninth routine international evaluation for dairy production traits took place as scheduled at the Interbull Centre. Twenty one (21) countries provided national data for this evaluation. Results were distributed on August 10, 1998, to designated representatives in a total of twenty three (23) countries currently subscribing to the service.

International genetic evaluations for milk, fat and protein yields of bulls from Canada, Germany, Denmark, Finland, France, Italy, the Netherlands, Norway, Sweden, the United States of America, Switzerland, the United Kingdom, New Zealand, Australia, Austria, Ireland, Spain, the Czech Republic, Slovenia, Estonia and Israel were computed. Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey and Simmental breed data from 8, 10, 4, 22, 7 and 7 bull populations, respectively, were included in this evaluation.

Changes compared to the previous (February 1998) INTERBULL evaluation

New data (national genetic evaluations):

• Red Holstein data from Switzerland were included for the first time in the Interbull Holstein evaluation. National genetic evaluations for Red Holstein in Switzerland are computed separately and at a different site than for Black & White Holstein, therefore, genetic evaluations of the two bull populations are not directly comparable. Swiss Red Holstein data were included in this Interbull evaluation as a new country-breed population, separate from the Swiss Black & White which had been already included since 1996.
• New national genetic evaluations for Holstein were computed in Germany using a test-day model and included in this Interbull evaluation. New estimates of sire variance were higher than before and genetic correlations with other populations generally decreased.
• New national genetic evaluations for Holstein, Jersey and Brown Swiss were computed in Denmark using an animal model (previously sire/MGS model) and included in this Interbull evaluation. New estimates of sire variance were lower than before and genetic correlations with other countries generally increased.
• New national genetic evaluations for Holstein were computed in Italy using a modified model and included in this Interbull evaluation. The following changes had been considered nationally: 305-d projection for 2nd and later parity records, new definition of phantom parent groups, and new heterogeneity of variance adjustment.
• Systems to identify non-AI and import (second proof) bulls in some countries are still in development stage; this may account for differences in national data set sizes from one evaluation to the next, in addition to young bulls first entering the system. In all such countries, progress is being made towards consistent definition systems. Non-AI bulls are not included in Interbull evaluations whereas import bull proofs are subject to stricter editing criteria ie, presence of first country proof in the Interbull data and second country proof based on minimum 75 daughters in 50 herds (40/20 for breeds other than Holstein).

Changes in the INTERBULL evaluation

• A new method to estimate reliability/repeatability of international genetic evaluations was applied. The method is attributed to Bevin Harris and David Johnson of LIC, New Zealand, and is described in their article "Information source reliability method applied to MACE", Interbull Bulletin No. 17. This method makes better use of the different sources of information than the previously used approximation. In general, reliability estimates decreased in countries where bulls have no own daughters.
• National genetic evaluation results from Belgium were not included in this Interbull evaluation, on this country's request, and in view of upcoming changes in the national genetic evaluation system in this country. New data from Belgium will be considered in the next test run.

Data and method of analysis

Data were national genetic evaluations of AI sampled bulls with daughters in at least 10 herds. Table 1 presents the type and amount of data included in this Interbull evaluation. The difference between "No. Records" and "No. Bulls" is explained by common bulls with proofs in more than one country. The entry "Publishable Proofs" reflects bulls whose international evaluations were distributed to service customers. The difference between "No. Bulls" and "Publishable Proofs" is explained by bulls not meeting the minimum criterion for official publication in the country of origin.

Estimated genetic parameters are shown in APPENDIX I. Parameters are listed by breed, trait, and country.

National proofs were first de-regressed within country and then analysed jointly with a linear model including the effects of evaluation country, genetic group of bull and bull merit. Different breeds were analysed separately. Heritability estimates used in both the de-regression and international evaluation were as in each country's national evaluation (Table 1).

Ancestor-bulls without own proofs were traced back two generations from the oldest bulls with proofs in order to increase across country connections and account for the effect of selection.

Genetic groups were defined according to unidentified parents by national origin, breed and birth year of the bull and path of selection (sire, maternal grand-sire, maternal grand-dam). Birth year grouping was by 1-5 year periods. Smaller groups (consisting of less than 10 bulls) were combined.

Publication of INTERBULL evaluations

Results were distributed by the Interbull Centre to designated representatives in each country. The international evaluation file comprised international proofs expressed on the base and unit of each country included in the analysis. Hopefully such records readily provide more information on bull performance in various countries, thereby minimising the need to resort to conversions.

At the same time, all recipients of Interbull results are expected to honour the agreed code of practice, as decided by the Interbull Steering Committee, and only publish international evaluations on their own country scale. Evaluations expressed on another country scale may only be used for internal purposes.

Use of INTERBULL evaluations in various countries

Table 2 presents current national policies regarding use of INTERBULL evaluations in countries participating with data. These statements do not provide permission to any country for publication of international evaluations expressed on the scale of another country. Publication references pertain to each country's own scale.

Table 3 shows release dates of national and INTERBULL evaluation results in various countries.

INTERBULL conversions

Since all data are now becoming available, conversions are not as useful as before. When an international proof is available, customers of the service are encouraged to use this instead of a converted proof. Conversion coefficients were, however, computed from international evaluation results and may be considered "Proposed Interbull Conversions" for the interim until the next international evaluation run.

Next test international evaluation

The next test international evaluation is scheduled for September 1998. Countries wishing to enter the system for the first time or planning to submit new information (critically modified evaluation procedure, new breeds etc) for the next routine evaluation must have their data tested in this test run. Deadline for sending new data to the Interbull Centre for the next test run is September 1, 1998.

Next routine international evaluation

The next routine international evaluation is scheduled for November 1998. New data for that run should reach the Interbull Centre not later than October 30, 1998; in any case, the most recently received data will be considered. Results will be distributed on November 9, 1998.

Means of result distribution from the INTERBULL Centre

Electronic exchange of data is probably more efficient than anything else. Currently most countries in the service have established internet connections and receive international evaluation results on the day of their release. Subscribers to the service that do not already exercise this option are encouraged to consider it and establish an internet connection and ftp account. When such accounts are available, please provide their specifications to the INTERBULL Centre. Until then, data will be delivered in diskettes.

For more information about the international genetic evaluation service please contact the INTERBULL Centre: address: SLU Box 7023, 750 07 Uppsala, Sweden; tel: +46-18-671974; fax: +46-18-672648;

e-mail: Georgios.Banos_at_hgen.slu.se

e-mail: Freddy.Fikse_at_hgen.slu.se

e-mail: Jan.Philipsson_at_hgen.slu.se

e-mail: Dan.Englund_at_hgen.slu.se