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How To Handle A Genetic Disorder

January 10, 2009
 
 

 

Mark Gardiner of Gardiner Angus Ranch, in Ashland, Kan., says the ranch will continue to test its cattle for Arthrogryposis Multiplex (AM) and will rid its herd of AM-carrier animals. "We're moving forward," Gardiner says. "This will soon be history."


In mid-September 2008, the American Angus Association (AAA) announced that a genetic disorder had been identified in a specific bloodline of Angus cattle. The disease, Arthrogryposis Multiplex (AM), previously called Curly Calf Syndrome, is a lethal genetic defect that results in abnormal calves.

Calves that are afflicted with AM are stillborn with bent or twisted spines. The calves are small in size due to limited muscle development and their hind legs are often rigid and hyperextended.

Since the September announcement, Don Laughlin, director of member services for AAA, has spent most of his time on the telephone talking with cattle producers.

"It's been hectic answering questions from producers and providing updates as information becomes available. Producers want to know which pedigrees are affected and how to test for AM," Laughlin says.

About 8% of the Angus bulls tested to date are carriers of the genetic defect, which is caused by a simple recessive gene, Laughlin says.

The lethal defect is inherited in the same way that a recessive gene for red color, carried by a black Angus bull and a black Angus cow, can produce a red calf. When both parents carry the recessive gene for AM, the chance for a normal calf is 25%, the risk of a carrier calf is 50%, and the risk of an abnormal calf is 25%. When an AM carrier is mated to a "free" animal, half of the calves will be carriers of the genetic disorder.

"We're in the development stages of providing software that will identify cattle that go back to carrier animals so that purebred breeders will know which animals to test for AM," Laughlin says.

The association has amended its rules regarding the handling of genetic defects within the breed. One change is that calves born prior to Dec. 31, 2009, will be registered as whether or not they are AM carriers. After Jan. 1, 2010, a calf testing positive as an AM carrier will not be registered, Laughlin says.

Bonus Content:

Follow this link to read more on "Rapid advances in genetic research."

For complete information and updates on Arthrogryposis Multiplex visit the American Angus Association Web site. 

Click here for a listing of AI sires that have been tested for the genetic condition.

Follow this link for information about Gardiner Angus Ranch.

Companies that offer testing for AM:

Discovery process. The association was first notified about the condition in March 2007 when it received reports that a small number of calves had been born dead with bent and twisted spines, Laughlin says.

The AAA began sending some calves and necropsy reports to David Steffen, a veterinarian at the University of Nebraska who has worked with the association in the past on abnormal calf cases. He studied the reports of abnormal calves born in 2007 but was unable to determine the exact cause of the condition.

Arthrogryposis is a disease that can develop from several variables. Abnormal calves, often called Arthrogryposis calves, can be caused by a genetic defect, by a virus that infects a cow during gestation or by environmental factors such as cattle ingesting certain poisonous plants.

Steffen continued to investigate, monitoring the spring 2008 calf crop and studying several other abnormal calves reported to the association. In August 2008, Jonathan Beever, a University of Illinois animal science professor and researcher, notified the association that he felt there was an urgent need for genomic studies, Laughlin says.

Steffen and AAA worked with Beever to develop the genetic test for AM. Beever has helped identify and develop tests for several other genetic diseases of beef cattle. (See "Rapid Advances in Genetic Research" at www.beeftoday.com.)

The association's request in September 2008 for reports of any abnormal calves resulted in written and verbal reports on 48 calves suspected of having the genetic defect. Of those, 47 were tentatively traced to the widely used AI Angus bull GAR Precision 1680.

The abnormal calves had "1680" genetics on both the sire and dam sides of their pedigrees. Further testing has traced the genetic defect to the maternal grandsire of GAR Precision 1680, an Angus bull called Rito 9J9 of B156 7T26.

 

Don Laughlin, director of member services, says the American Angus Association moved quickly to inform producers about cattle that carry the Arthrogryposis Multiplex gene.
Positive approach. Mark Gardiner and his family, of Gardiner Angus Ranch in Ashland, Kan., owned GAR Precision 1680 and used the bull extensively in their breeding program. The bull had exceptional traits for carcass, calving ease and early growth and a stature that fit most environments, Gardiner says.

"All our animals go back to Precision 1680, and many also have Rito 9J9, so a high percentage of our cattle are descendants of Rito 9J9 and Precision," he adds.

About 2,500 females are bred through AI each fall at the ranch, which has used AI since 1964. From 1991 to 2008, about 27,000 calves have been produced. According to ranch records, 11 abnormal calves were stillborn. Last year, the ranch had one AM calf sired by a young test bull, Gardiner says.

Despite the news that their bloodlines are AM carriers, Gardiner is thankful technology has caught up and a test is available to identify cattle that carry the gene.

"We will lose some sires, but we'll go on. Not a single bull we planned to use last year tested positive for the gene," Gardiner says.

The ranch held its fall bull sale three weeks after the news about AM. Despite early hysteria and fear—the Gardiners fielded about 30 phone calls and 50 e-mails per day for a while—the sale averaged $500 more per animal than it ever had.

"Our message was clear. We fully guarantee our bulls and our customers understand that. We'll test all our young sires and move on. Some customers were worried their cattle wouldn't be worth as much. If the cattle are carriers, that is true. But the noncarriers are now worth more," Gardiner says. BT

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FEATURED IN: Beef Today - January 2009
RELATED TOPICS: Beef, Dairy, Calves, Cattle, Genetics

 
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