Illinois Researchers Identify Genetic Defect In Beef Cattle
US - University of Illinois researchers identified the mutation causing Contractural Arachnodactyly (CA; formerly Fawn Calf Syndrome), a genetic abnormality affecting Angus and Angus-derived cattle.
10 August 2010
2 minute read
Jonathan Beever, U of I associate professor in the department of animal sciences and lead researcher, said his team completed the correct assembly of the DNA sequence responsible for CA on June 8. Since then, they have developed DNA tests based on this mutation.
"CA is a genetic abnormality inherited as a simple recessive," Beever said.
"Some debate exists about its classification as a genetic defect because many CA-affected calves survive and can reach reproductive age. However, at the population level, CA behaves as a lethal genetic defect and should be classified as such."
A random sampling of AI sires provided from members of the National Association of Animal Breeders allowed researchers to accurately estimate the allele frequency while providing information on animals that have significant influence on the total population. A list of affected animals is available at http://www.angus.org/pub/CA/CA_Summary.pdf. To date, researchers have screened 1,256 AI sires and identified 39 bulls that are CA carriers.
Emerging technology and the successful mapping of the cow genome have allowed Beever's team to find solutions to genetic defects within months that previously took 10 years to solve. While the same research process is being followed today that was followed 20 years ago, they now have tools such as DNA chips that allow them to look at more than 50,000 DNA markers at once.
"In the beef cattle industry, one bad gene can cause a death loss," Beever said.
"As a cattle producer myself, I understand how devastating these losses can be to an operation and to the industry as a whole."
This type of research results in technologies that can almost immediately stop the spread of a genetic abnormality in a time of perceived crisis, he added. These tools also help breeders identify high genetic merit individuals within a particular line that may be associated with a defect, but are negative for the defect. Beever said this allows maintenance of the good genetics in the population, but limits the spread of the defect.
Research is under way to develop a commercially available CA test by September.
In the past six years, Beever's team has identified genetic markers for several genetic defects including tibial hemimelia (TH) in Shorthorn cattle; idiopathic epilepsy (IE) and hypotrichosis (hairlessness) in Hereford cattle; arthrogryposis multiplex (curly calf syndrome), neuropathic hydrocephalus in Angus cattle and pulmonary hypoplasia with anasarca (PHA) in Maine-Anjou cattle.
For more information on the phenotype associated with CA, go to http://www.dpi.nsw.gov.au/agriculture/livestock/health/specific/cattle/ca-angus.
