Holstein Association USA will declare Early Onset Muscle Weakness Syndrome (MW) as an officially recognized genetic condition beginning in February 2024. Holstein Association USA’s Genetic Advancement Committee recently endorsed a recommendation from staff to do so. The recommendation comes after their analysis of the MW haplotypes following the December 2023 genetic evaluations. Comments from Holstein breeders and scientific researchers further support this decision.
“This latest review provides more evidence and support on the recent action taken by the Holstein Association USA Board of Directors to add Early Onset Muscle Weakness to the list of officially recognized genetic conditions in February 2024,” says Dr. Tom Lawlor, Holstein Association USA’s Executive Director of Research and Development. “Soon, we’ll have MW in the rearview mirror as we move ahead with our genetic advancement of the Holstein breed.”
Starting in February 2024, direct gene test results for MW will be labeled on Official Holstein Pedigrees, and other products where officially recognized genetic conditions are displayed.
The following codes will be used to designate animals with official gene test results on file:
- TE = tested free of MW
- MW = Heterozygous Carrier
- MW2 = Homozygous Carrier
Breeders can forward lab reports for MW test results to labresults@holstein.com to have them added to the Holstein Association USA genetic conditions database.
MW haplotype results were made available for all genomic-tested animals in conjunction with the official genetic evaluation release on December 5, 2023. This information can be found in the same place as other haplotype information, including the free Family Tree Search, within Red Book Plus Online, on genomic reports, and within Enlight.
Results for MW haplotypes are reported as 0 (free), 1 (carrier), 2 (homozygous affected), 3 (suspected carrier), or 4 (suspected homozygous) on evaluations.
MW Resources
Additional resources and information on MW can be found on the Holstein Association USA website. A regularly updated list of bulls with a NAAB code that have a direct test result on file can be found at https://www.holsteinusa.com/lists/early_onset_muscle_weakness.html.
The best tool available for discovering and understanding new genetic conditions is farmer reporting. Farmers who have calves born with abnormal features or health issues that are suspected to be caused by genetic problems are asked to complete the Abnormality Report Form available at https://www.holsteinusa.com/pdf/forms_apps/abnormality_report.pdf and email it to LabResults@holstein.com, or contact the Genetic Services department at 800.952.5200.
For more background on the previous steps taken regarding MW, see Holstein Association USA’s December 2023 press release at https://www.holsteinusa.com/news/press_release2023.html#pr2023_29. Look for an article in the upcoming Winter 2024 issue of The Pulse for more detailed information.
