Since 2019, American dairy farmers began to notice a few calves in their herds that couldn’t stand up. The incredible power of genetic testing found the culprit. According to collaborating researchers from Penn State University and the USDA’s Agricultural Research Service, the cause is a newly discovered genetic defect in Holstein cattle. Known as calf recumbency, the stricken calves were otherwise healthy animals.
In a 2022 study of four large farms (2 in New York, 1 in Florida and 1 in Pennsylvania), researchers found 34 Holstein calves that could not stand without assistance and most died within six weeks. Only seven calves recovered.
According to the study published in the JDS Communications, the official journal of the American Dairy Science Association, “33 affected calves with sire identification and all 24 affected calves with at least 5 generations of known maternal sires were traced to a bull born in 2008 who was considered a likely carrier ancestor. One prolific son of that bull was born in 2010 and was present in 30 of 33 paternal lineages and 23 of 24 maternal lineages. There were 66 daughters of the son with genotypes (48K to 77K) available from farm 3, the Pennsylvania State University dairy herd, and 3 commercial herds. Semen was obtained from the son to facilitate genotyping … which confirmed that the son was a carrier of the suspect haplotype.”
A haplotype is a set of DNA variants along a single chromosome that tend to be inherited together.
Acknowledging the urgency of addressing this defect, the industry is prioritizing the provision of accurate diagnostic tools while ensuring transparent communication of carrier statuses for affected males and females.
In the United States, Genetic Visions and Feanix Bio currently offer two commercial gene tests to determine carrier status for this defect.
Additionally, ongoing efforts are being made to establish a defined system for delivering test results from laboratories to the Council on Dairy Cattle Breeding (CDCB) and Holstein Association USA. The USDA’s Animal Genetics and Improvement Laboratory (AGIL) and CDCB are collaborating on the development of a more precise haplotype test, with hope that it will be available this year.