ABS Collaborates to Identify Cause of Early Onset Muscle Weakness Syndrome

Publish date: 2.21.24 

As most should be familiar, in 2022, a new haplotype was reported that was associated with calf recumbency or muscle weakness in Holsteins which was announced by the Holstein Association USA in April 2023. This genetic defect was originally termed ‘Calf Recumbency’ but has since been renamed ‘Early Onset Muscle Weakness Syndrome.’ While not much has changed in terms of the mutation, we wanted to provide you with more information and give you access to learn more about the research that uncovered this mutation.  

In a collaborative research project, Penn State University led the charge in uncovering the unfavorable genetic condition and recessive gene termed Early Onset Muscle Weakness Syndrome. ABS Global is proud to have been included in the project amongst other researchers. To recap, this mutation resulted in newborn calves being unable to stand and higher death rates. The team used whole genome sequence data to pinpoint an allele within the CACNA1S gene that affected muscle movement. With this information, there have been improvements made in pedigree tracing of the DNA and direct genetic tests for the mutation. This allows for selection and mating programs to reduce the occurrence of Early Onset Muscle Weakness Syndrome.  

The Council of Dairy Cattle Breeding released the haplotype for Early Onset Muscle Weakness Syndrome with December 2023 Sire Summary. The haplotype results include a variety of carrier, non-carrier, and “probable carrier” denotations.  The “probable” bulls are likely true carriers, but around 3% are identified as non-carriers when tested directly for the causative gene. We should note that the Holstein Association officially recognized Early Onset Muscle Weakness Syndrome as a recessive gene at the beginning of February 2024. Read more about it in this press release from the Holstein Association USA.  

With the industry gaining more knowledge regarding Early Onset Muscle Weakness Syndrome, ABS Global stayed dedicated to making sure we offer the best genetics possible to our customers. ABS has tested all of our globally marketed Holstein bulls, regardless of where they are standing, and listed their results in Bull Search. Today, we utilize those known results in our Genetic Management System (GMS) as well as known results of industry bulls. As leaders in the industry, ABS will continue to monitor this and keep you informed. 

To learn more about Early Onset Muscle Weakness Syndrome, complete the form below.