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Do you know what’s crawling on your cows?

Eastern Virginia cattle producer Steve Hopkins knows when his 300 brood commercial Angus and SimAngus cows are out on their lush summer pastures they’ll encounter a pest or two.   

But, the ones his cows were hosting four years ago were worse than he could have imagined. 
 
In 2018, Riverview Farms lost seven of their brood. A year later they lost 2 out of 22 bred cows Hopkins had recently purchased.

At first, Hopkins suspected it was anaplasmosis, a common blood parasite tick-borne disease. But, when he treated the cattle for it, they didn't respond to the antibiotics. A call to his veterinarian and one blood test later, Hopkins would learn that  95% of his herd had thelia orientalis ikedia, also known as Theileria. 

"Once you have the first wave, it gets better. All those that made it through are now resistant," Hopkins says. 

Theileria is a disease caused by a blood-borne parasite that feeds off cattle's red and white blood cells. The disease is spread by the Asian Longhorn, an invasive, exotic tick from northeast Asia that migrated to Australia. The USDA discovered the tick in 2017 on sheep in New Jersey.

Since then, the tick’s spread has grown. There have been cases in 17 states, most in the Mid-Atlantic, including Virginia, Pennsylvania, Delaware, and New York. Recently, the tick was on two breeding bulls that fell ill and died in Kentucky, according to the state's department of agriculture. 

"This is troubling because this tick is spreading quickly and efficiently throughout the United States," says Lindsay Fry, a USDA Veterinary Medical Officer. 

Unlike the common deer and cattle fever ticks, the Asian Longhorn females are parthenogenetic, which means a female doesn't need a male to reproduce. 

"Males aren't needed. So, a single female tick can give rise to a new group of ticks if it gets moved," Fry says.  

Fry spoke on the emerging issue of Asian Longhorn ticks on August 24 at a National Cattlemen's Beef Association webinar. 

For cattlemen like Hopkins, no approved treatment or vaccine is available to fight infection. 

Fry has been doing clinical research on the tick that carries Theileria for a decade. She and her team are working on developing a treatment and a rapid chute-side diagnostic test for producers. 

Cattle with Theileria will show symptoms similar to anaplasmosis. They will become frail, weak, and have a high fever. But, those symptoms will appear more rapidly in a herd, Fry says.

In a clinical trial, Fry and her team found the parasites on blood smears within 14 days of the first day of feeding on a group of calves showing mild signs of anemia. 

As the second wave of Theileria hit some of his purchased cows in 2019, Hopkins noticed that he needed to be cautious when introducing new cattle into his herd before a stressful event like calving. 

He tries to limit their exposure to any additional stress pre-calving. For example, Hopkins won't mix his bred heifers that may not be resistant to the disease with cows that are positive in the ten weeks before their calving date.

"We try to let them be calm and stress-free as much as possible after they are exposed to positive cows for the first time," he says. 

Once an animal has overcome the acute stage of Theileria, Fry’s trial revealed that it will become a carrier and can transfer the disease to other cattle in the herd. 

The spread doesn't just happen on the farm through infected cattle. Fry says the tick also likes to feed off other livestock like sheep, goats, and wildlife such as white-tailed deer, raccoons, and field mice. 

But cattle are their favorite host. 

The economic impacts of ticks, especially the Asian Longhorn, can be severe on a cow-calf operation, which is already a low-margin business.
 
Brent Credille, associate professor of the University of Georgia, who joined Fry on the NCBA webinar series, says the average profit and loss for a cow-calf farm is about $50 to $100 per cow. 
 
"When ticks are on an animal in significant numbers, they can cause substantial production losses," he says. 

One of the noticeable effects of ticks is weight loss. Cows with significant weight loss can miscarry or remain open. Another is damage to a cow's hide.

"Hides for a packer are a source of income, and any damage to that hide is going to reduce what you get when that animal is sold," Credille says. 

Producers can take measures to control ticks within their pasture and herds. But the efforts won't completely eradicate the tick. 

"Let me assure you there are not enough chemicals in the world to eliminate ticks," says Nancy Hinkle, an entomologist at the University of Georgia. "They are tough little critters and can hide, so no amount of pesticide will get to every one of them."

Recent research from the University of Tennessee has found that bush-hogging pastures monthly reduces tick numbers, but that is a time, labor, and fuel expense many producers can't afford. 

"Since the Asian Longhorn tick is more numerous in woods along pasture edges, mowing pasture margins might be more important than mowing the entire pasture," Hinkle says. 

Producers can pair their mowing with spraying an approved kerosene insecticide to maximize their efforts. 

Hinkle also advises producers to think about the timing of their mowing. 

"As we go from summer into fall when the females are laying their eggs and dying off while tick larvae are hatching and prepping for overwintering, it might be a critical time to reduce negative cover and maximize tick mortality," she says. 

Credille says producers should include insecticide pour-ons, sprays, and ear tags in their arsenal against the Asian Longhorn tick to keep a herd’s defense strong.

"You want to think about where those ticks are attached, so you get the best distribution," he says.

Ticks like to nestle in on a cow's head, ears, brisket, and trailhead. They can also be found on the udder and between the legs. 

"These sprays and pour-ons are going to have about two weeks of persistent activity depending on the product you use," Credille says. "They are not meant to be season-long control but can get you some effect for a short period."

On his farm, Hopkins uses an insecticide pour-on two times a year. In the summer, he uses fly-proof ear tags that last about five months to prevent further invasions of ticks on his cows. In addition, to minimize the spread of infection during vaccinations on calves and heifers, Hopkins switches out needles for each animal. 

Biosecurity is another measure producers can use in their management to prevent Theileria. For example, quarantining cattle for two to four weeks or more provides added time for observation of ticks and other diseases, Credille says. 

Even with his management efforts, Hopkins still feels vanquishing the pest is a never-ending challenge for his herd. 

“You just can't control these ticks,” he says.
 

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