Genetic mutations are not unusual in the cattle industry, but a recently discovered genetic mutation with lethal results has spawned concern in the Angus community.
Arthrogryposis Multiplex (AM) in Angus cattle is a genetic condition commonly referred to as "Curly Calf Syndrome," resulting in calves born dead with twisted or bent spines.
Since early September, researchers at the University of Illinois and the University of Nebraska, in collaboration with the American Angus Association, have been investigating the genetic condition that appears at this time to be a simply inherited recessive genetic defect.
Beyond the basic concern that comes with finding a recessive gene that carries a lethal genetic defect, researchers have identified that a carrier of the gene is a very popular bull in the Angus breed, GAR Precision 1680.
The Breed Impact
Much like a carrier of the recessive gene that would result in an offspring having in blue eyes or red hair, AM is a genetic condition that cannot be identified by sight until the dead calf is born. Angus cows/bulls that are carriers of the AM gene look perfectly normal, there is nothing in the way the animal looks that would indicate that the animal is a carrier of the AM gene.
"With a lethal recessive gene like AM, if a carrier bull is mated to a carrier cow there is a 25 percent chance the calf will have Arthrogryposis Multiplex and be born dead," explained Darrh Bullock, University of Kentucky Beef Extension Specialist. "However, there is a 50 percent chance that this mating will produce another carrier and a 25 percent chance that it will have two normal genes."
As a result, producers have been using cattle carrying the AM gene in their breeding programs (both registered and commercial) and have passed the gene on to another generation. This has propagated the recessive gene within the cattle population.
Producers acknowledge that AM research is still in its infancy, so making breeding decisions in an operation can prove to be difficult.
At this time it is uncertain how many bulls and cows are carriers of the lethal recessive gene, but the American Angus Association is currently working to develop DNA markers that will allow producers to test their animals to identify carriers of the gene. Once this test is available, it will be much easier to eliminate the carrier animals, and ultimately the gene, from the population.
The Angus Industry
It is important to note that if an animal that is an AM carrier makes it into the food chain, there will be no impact on the safety or quality of the meat.
"This is just a gene like the gene that makes the cattle black or red," explained Bullock. "Consumers should not be concerned about the safety or eating quality of the meat; the only need for concern is within the beef industry in eliminating the loss of calves."
In fact, where this issue could really hit the industry hard is on the economic side. Many breeds have had to deal with genetic abnormalities in the past; the big difference with AM is that it is impacting the largest breed population in the country.
The use of artificial insemination for breeding has led to a single bull, like Precision, being used by breeders across the nation. The additional practice of line breeding to select for qualities that are superior within a particular animal has concentrated the gene to the point that it is now being expressed.
As one producer noted, the expression of the AM gene is a byproduct of successful breeding. The traits that were desirable in Precision have been breed generation after generation, and as a result two recessive genes are expressed and AM is the result.
"This is a serious situation that Angus breeders and the American Angus Association are diligently working to resolve," Bullock said. "There is no need to panic, and drastic measures should be avoided until more information is known."
To check the current status of Arthrogryposis Multiplex and to stay abreast of the ongoing research, visit the American Angus Association's Web site at www.angus.org.