The American Angus Association, other breed associations and cattle health specialists are using modern DNA technology to tackle an old problem, and it's hoped the result will be a much smaller impact than in the past on producers and the industry.
The problem is a hereditary defect. In this case, the defect — Arthrogryposis Multiplex (AM), which was until recently called "Curly Calf Syndrome" — has been traced to descendants of a popular Angus sire, GAR Precision 1680. Over a 10-day period in September, in response to an inquiry to AAA members, 48 producers said their cows' stillborn calves appeared to have the defect; 47 turned out to have Precision on both sides of their pedigrees.
Wes Tiemann, AAA regional manager for Iowa and Missouri, said every breed has had to deal with the discovery of genetic defects over the years. "Back then," he said, "we totally had to eliminate that lineage of cattle from our herd because we had no way of testing, just figuring out which offspring's a carrier or non-carrier."
But the gene that causes the syndrome—the name comes from the condition of the dead calves, with bent and twisted spines, and limbs that are often stiff and either hyperextended or contracted — is a simple recessive; it has to be present in both parents to be expressed. If both parents have it, there's a 25 percent chance the calf will be born dead, but a 50 percent chance it will survive and be a carrier.
Tiemann said with this knowledge, "We can go through our herd books and find out the cattle that could possibly be carriers or possibly be affected by this. So, we're just letting our breeders and producers know right now, if they have those certain bloodlines, to be careful how they're mated."
The Angus Association has adopted new policies and rules governing defects within the breed, including AM. Chief Operating Officer Bill Bowman explained cattle can keep existing registrations despite presence of the defect. "They can be tested," he said, "and their test data, once we have approved labs set up, can provide that information to us, and that would be marked on their pedigrees."
Between now and the end of 2009, animals out of a known carrier can be registered, provided they've been tested; beginning Jan. 1, 2010, only animals free of the mutation can be registered.
Dr. Jon Beever, a molecular genetics professor at the University of Illinois, has developed a DNA test that indicates whether an animal has the mutation; Bowman said the University is in the process of licensing the test so it can be offered commercially "With this technology that's available to us," he said, "we're really able to identify those cattle out of that line of impacted genetics, and identify the cattle that are free of the gene. They can still make a major contribution to our breed and the beef industry."
Thirty or 40 years ago, he said, it would have been different. In the 60's, dwarfism was in both Angus and Hereford genetics. "At that time," Bowman said, 'those lines were just totally eliminated, because that was the easiest way to know that you were not going to propagate that gene any further." Similarly, Angus purged a line in the 70's that carried a gene for syndactyly ("mulefoot"). "All species have to deal with genetic abnormalities," he pointed out.
"It's something that's natural occurring, and we just are thankful that now, we have a way to better manage and identify those cattle that are carriers," Beever said.
Tiemann added although the suspect genetics won't be used as heavily as it has been for the last five years, they'll never be totally be weeded out. "But," he added, "all things go that way; we have to open up our breed and use other sires along the line, anyway, until we're line breeding, again." Although large scale commercial operators may want to test animals of unknown parentage to avoid unwittingly matching carriers, Tiemann said producers he's talked to who have questions about their animals' pedigrees will "go back to their bull supplier and say, 'Hey, the bulls I've been buying the last five years; is there a chance I need to be careful and watch out for this?' We're just using good faith and a breeder's knowledge of what they've been giving to their customers."
Tiemann predicted in the next two or three years, "we're really not going to hear much about Curly Calf Syndrome anymore, because those cattle that are carriers will be gone, and the cattle that are free will still be here…This will just be a mere bump in the road, and within the next couple of years we'll look back and see it as a smaller thing than what it actually is, just because there's really not that many cattle that were affected by it."
