Interbull Routine Genetic Evaluation for Udder Health Traits

May 2006

Introduction
International genetic evaluations for milk somatic cell and clinical mastitis of bulls from Canada, Czech Republic, Denmark, Estonia, Finland, France, Germany, the Netherlands, Norway, Sweden, Switzerland, The United Kingdom, The United States of America, Israel, Italy, Australia, Hungary, Belgium, Japan, Spain, Rep. South Africa New Zealand and Ireland were computed in this evaluation. Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey and Simmental breed data  
were included.

Changes in national data

• Czech Republic participated for the first time in the Holstein and Simmental
  evaluation.
• Rep. South Africa (Jersey) changed the definition of fixed effects, introduced pre-adjustments for heterogeneous variances and updated the genetic parameters.
• Norway changed to a multiple-trait model for clinical mastitis. Seven periods spread over three lactations are considered as different traits.
• Switzerland (Brown Swiss) changed the definition of fixed lactation curves (grouping of years shifted by one year). At the same time the reference base was updated.
• New Zealand applied more stringent convergence criteria.
• Ireland fixed a problem in the data extraction.
• Italy (Simmental) changed the definition of phantom parent groups.

Changes in Interbull international evaluation compared to:
- February 2006 routine evaluations

• Direction of scale was included for the March test run.

Data and method of analysis

Data were national genetic evaluations of AI sampled bulls with daughters in at least 10 herds. For clinical mastitis information to be included, an additional requirement was that bulls had to have at least 50 daughters. Table 1 presents the amount of data included in this Interbull evaluation. Table 2 and table 3 gives heritabilities and some additional information on national evaluations as provided by the participating countries.

Estimated genetic parameters are shown in APPENDIX I and the number of common bulls are listed in APPENDIX II..

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. Heritability estimates used in both the de-regression and international evaluation were as in each country's national evaluation (Table 2 and table 3).

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 30 bulls) were combined. 

International genetic evaluations were computed using effective daughter contributions (EDC) as weighting factors.

For each breed, two separate international genetic evaluations were computed. The first included milk somatic cell de-regressed proofs from individual countries. The second included de-regressed proofs for clinical mastitis as a direct trait from countries that made this information available and milk somatic cell de-regressed proofs from all other countries. Note that the second evaluation was not carried out for BSW and GUE since none of the participating countries provided clinical mastitis information.

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. 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, decided by the Interbull Steering Committee, and only publish international evaluations on their own country scale. Evaluations expressed on another country scale are confidential and may only be used internally for research and review purposes.

All recipients are also expected to follow the agreed guidelines for advertising genetic merit. The guidelines has been distributed to all members and is available on the Interbull homepage (www.interbull.org) under "Publications and Documentation/General information".

Genetic correlation estimation procedure

See www.interbull.org/documents/genetic_correlation_estimation_procedure_042t.pdf

Next routine international evaluation

The next routine international evaluation for dairy production, udder health conformation, longevity and calving traits (Holstein) is scheduled for August 2006. New data for the August routine run should reach the Interbull Centre not later than Tuesday July 25, 2006, 17:00 Central European Time (CET); in any case, the most recently received data will be considered. The target time for distribution of results for internal review to designated representatives, who have signed a confidentiality agreement with the Centre, is Thursday August 3, 2006. Official release date of the results is targeted to be Monday August 7, 2006.

Next test international evaluation

The next test international evaluation for dairy production, conformation, udder health, longevity and calving traits (Holsteins) is scheduled for September 2006. Countries wishing to enter the system for the first time or planning to submit new information (modified national evaluation procedure, new breeds etc) for following routine evaluations must have their data tested in this test-run.

Deadline for sending data and validation results to the Interbull Centre for the next test-run is September 1, 2006 at 17:00 CET.
 

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 has 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 on CD-ROM's.

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

Please use Interbull_at_hgen.slu.se for all communication regarding Interbull services.