New threats to the cattle herd have emerged this year, while old ones never seem to go away. A pair of congenital fatal defects have emerged in cattle with Angus genetics; diseases thought to be eradicated from the U.S. herd, like brucellosis and bovine tuberculosis, periodically resurface. And ranchers need to stay on their guard. The University of Missouri's past livestock Extension specialist and University of Arkansas' associate professor of veterinary science weigh in on this issue.
The fatal defects, arthrogryposis multiplex (AM or “curly calf”) and neuropathic hydrocephalus (NH, “water head”), are both coincidental to the Precision 1680 pedigree, said Bob Weaber, University of Missouri Extension beef cattle genetics specialist and Assistant Professor of Animal Science. “A genetic test has been developed for both of those,” he told Ozarks Farm & Neighbor, “a DNA diagnostic.”
Weaber said it’s likely 1680 genetics have been used extensively, but since both AM and NH are recessive traits, their expression can be prevented strictly by controlling the sire end. If producers have registered Angus bulls, he said, “they can go to the Angus website, look those animals up and see if they’ve been classified as potential carriers of the defect. That will give them a little peace of mind that they’re clear by pedigree, so they don’t have to worry in terms of having that carrier in their herds.”
If they find one or more of their bulls are carriers, the next step would be ensuring that any replacement heifers being held back are mated to bulls that are determined to be free of the defects, either through testing or by examining their Angus Association pedigrees. “Having carriers in your herd isn’t that big of a deal if you know you’re mating those cows to bulls that are clean,” Weaber said. “Go through your bull battery; if they come up with a potential carrier on the website, it may be worthwhile to go and test those bulls.” If they come back positive for the genetic defect, it may be a good idea to cull them off; the cost of the test, he said, “is relatively modest for the peace of mind that you get out of it.”
A number of other factors can lead to a stillborn calf, like nutrition and disease; even if a cow does produce an NH or AM calf, the solution in the future would be mating her to a bull that’s negative for both traits. “With the cost of replacement females,” said Weaber, “my aggressiveness towards culling is pretty significantly diminished."
But this year’s revelations, he said, present yet another argument for genetic diversification of the herd. “We’ve produced pedigree structures that are relatively tight,” Weaber said. “And there’s undoubtedly more of these genetic defects out there; if you take the Holstein breed as an example, every 2-3 years they discover a new genetic defect from that population.” He believes in many cases, cows remain open due to undetected genetic defects that result in early embryonic deaths, and urges producers to “do a little more homework than just the basic three-generation pedigree, to keep some diversity in that pedigree.” Commercial producers, too, can easily address the problem with crossbreeding; most identified defects only circulate within a single breed’s genetics.
As for heading off disease, Jeremy Powell, Associate Professor of Veterinary Science at the University of Arkansas-Fayetteville, said it starts with making sure cattle that enter the herd from out of state have their veterinary inspection health certificates in order. Then, said Powell, make sure new animals are quarantined. “An isolation period of 3-4 weeks would be good, so it didn’t have any fenceline contact or share water sources or feedbunk space with other animals in your herd,” he told OFN.
Keep an eye on the animals under quarantine; if they show signs of disease, they can be treated or removed without exposing the rest of the herd. It’s also a good idea to continue to monitor animals in the herd, and train hired help to recognize disease. “Once the animal’s identified as sick, then you call the veterinarian so that the correct treatment can get underway.”
Another important method of disease control is vaccination; among the annual shots Powell recommends are lepto/vibrio, a four-way viral injection for IBR, BVD, PI3 and BRSV, and blackleg. “If they’re going to be replacing the heifers,” he said, “then we also recommend vaccinating for brucellosis, so that they’re taken care of when they come back into the herd.”
Powell recommended basic traffic control, preventing wild animals from getting into grain storage areas. “Just trying to keep things clean and sanitized,” he said, “as far as making sure that they have changed clothes or cleaned their boots if they’ve been at a livestock sale, county fair or someone else’s farm before they get back home to their farm, will help reduce the spread of potential diseases.”
