INTERBULL Routine Genetic Evaluation for Dairy Production Traits
August 1997

Please Note. For questions about international sire proofs, please contact the INTERBULL member organisation for your particular country. Contacts for INTERBULL member organisations are available at this site.

Introduction

The seventh routine international evaluation for dairy production traits took place as scheduled at the INTERBULL Centre. Twenty (20) countries provided national data for this evaluation. Results were distributed on August 11, 1997, to designated representatives in a total of twenty two (22) 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, Belgium, Ireland, Spain, the Czech Republic and Slovenia were computed. Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey and Simmental breed data from 8, 10, 4, 19, 6 and 6 countries, respectively, were included in this evaluation.

Changes compared to the previous (February 1997) INTERBULL evaluation

Changes in INTERBULL evaluations:

- Simmental breed evaluations were considered for the first time. Participating countries were: Austria, Switzerland, Germany, France (Montbeliarde), Italy and Slovenia.

- Slovenia participated with data for the first time in the Holstein, Brown Swiss and Simmental evaluations.

- Evaluations for breeds other than Holstein were computed based on national evaluation data for just those bulls born since 1975. This change in policy was the result of extensive research in collaboration with the University of Wisconsin-Madison, USA, presented to and discussed with representatives of all participating countries at a technical workshop in November 1996 in Germany. The theoretical justification and merit of such edit had been provided by a series of simulation studies and tested with field data analyses. All identifiable pedigree information was included in the evaluation. As before, Holstein evaluations were based on bulls born since 1980.

Changes in national evaluations:

- New heritability estimates in the US national evaluations were .30 (previously .25) for all traits and breeds.

- Brown Swiss evaluations in Switzerland were based on maximum five lactations per cow (previously four); also definition of number of herds considered only herds where first records were made (previously all).

- Systems to identify non-AI and import (second proof) bulls in some countries are still in development stage; this may explain 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 establishing consistent identification 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).

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.

Accuracy (reliability/repeatability) of international proofs was based on block-diagonal submatrices specific to each bull. Each submatrix consisted of the number of daughters in each country, the diagonal from the inverse numerator matrix, and the sire (co)variance matrix. Consequently, international proofs of the same bull had different accuracies in different countries depending on the amount of information and the genetic parameters.

Admittedly, the current method of estimating accuracy (reliability/repeatability) of international proofs is not perfect. Research is currently being conducted to improve the method.

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. Tendency to harmonise such release dates has been noted in several countries. Adoption of this policy by all participants would increase the overall value of the service.

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 October-November 1997. Countries wishing to enter the system for the first time or planning to submit new information (critically modified evaluation model, new breeds etc) for the next routine evaluation must have their data tested in this test run. Deadline for sending data to the INTERBULL Centre for the next test run is October 1, 1997.

Next routine international evaluation

The next routine international evaluation is scheduled for February 1998. New data for that run should reach the INTERBULL Centre not later than January 30, 1998; otherwise the same data used in this run will be considered. Results will be distributed on February 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

Table 2. National policies regarding use of INTERBULL evaluations for dairy production traits (August 1997) by breed of evaluation where each country participates.

Table 3. Release dates of national and INTERBULL evaluations for dairy production traits in relation to August 1997 and February 1998 INTERBULL runs; applies to all breeds unless otherwise stated.