Put Health to the Test

April 25, 2015 02:19 AM
Put Health to the Test

Calves exposed to persistently infected bovine viral diarrhea (BVD-PI) animals are at greater risk for BRD as well

Cattlemen are pretty good at spotting visual signs of a sick calf. A calf that needs treatment might be lethargic, off feed, head down and leaking out of both ends. Odds are that calf will be doctored and, hopefully, brought back to good health.

Where producers run into trouble is trying to diagnosis bovine viral diarrhea (BVD) in a persistently infected (PI) calf. It’s not as simple as looking for visual signs.

“BVD is probably the most under-diagnosed disease we see in cattle,” says Bill Hessman, a veterinarian in Sublette, Kan. Only 0.3% to 0.5% of the population can be identified as BVD-PI. 

“There are studies that show 70% to 90% of BVD infections are subclinical—it means they’re going on, but the animal doesn’t show the signs,” Hessman adds.

When a BVD infected animal does show signs of illness, it’s typically another ailment caused by the BVD infection. Research on feedlot cattle in the Texas Panhandle by the feedlot research group at West Texas A&M University from 2005 indicated 15.9% of the cases of bovine respiratory disease (BRD) observed were a result from exposure to a BVD-PI calf.

Identifying those BVD-PI calves before they ever make it to the feedlot is crucial and has big impacts on the bottom line. To locate a BVD-PI calf, a skin sample is pulled and sent to one of many testing labs. 

Hessman offers BVD-PI testing at Central States Testing labs, located in several facilities across the country. Central States Testing uses an Antigen Capture Elisa (ACE) method for individual animal tests from ear notch samples.

Because the tests are individualized, they are more expensive than tests at some labs that pool samples from several animals. The cost starts at $3.15 per head and has a scaled pricing system based on volume. The average price of each test tends to be $2.55 per head. 

Hessman says the additional cost is worth it when considering the losses witnessed from a study he performed at Cattle Empire Feedlot near Satanta, Kan. In 2009, nearly 22,000 high-risk calves from the Southeast were tested for BVD. Calves were then sorted into different pens, with some containing a BVD-PI calf and others being a clean group.

The resulting data revealed calf mortality accounted for $5.26 per head in lost profit, while performance losses averaged $88.26 per head when there was a BVD-PI calf in the pen. 

At Central States Testing, an Antigen Capture Elisa test is done on calf ear notches to determine BVD-PI status. Tests for BVD-PI are available at many labs, including university veterinary diagnostic labs.

“The feed conversion was dramatically impacted when they had exposure to BVD-PI animals,” Hessman says. Cattle exposed to BVD-PI cattle converted feed 55% less effectively than their counterparts.

Testing calves of unknown origin for BVD-PI, such as sale barn cattle out of the Southeast, is smart not only at the feedlot level but at the backgrounding stage.

The father and son team of Frantz and Mike Betschart in Ashland, Kan., have been testing those types of calves for well over a decade. Every year, each of the approximately 5,000 to 8,000 calves going through the chute at the backgrounding yard are BVD-PI tested. The calves coming in weigh 300 lb. to 400 lb., so oftentimes, they’ve recently been weaned, commingled at a sale barn and then trucked to Kansas. 

Stress plays a big role in the productivity of the calves and the onset of sickness. Frantz admits to at one time being “pretty naive about BVD.” Prior to testing, he had a health wreck with some steers that had been in his care for more than 45 days. Calves kept getting ill and dying, so he contacted Hessman and decided to test the whole pen.

“Sure as the world, there was one BVD-PI steer in there,” Frantz says. 

The carrier calf was taken out, and soon the health of the cattle made a big turnaround.

“That one steer was creating all of the problems,” Frantz says. “That right there made a believer out of me that they need to be out of there.”

Now, when a BVD-PI calf is found, the Betscharts isolate it in a quarantine pen with other carriers. Rather than taking the BVD-PI calves to the sale barn, where they’ll just infect more cattle, the carriers are fed out to butcher locally. They tend to gain slower and are processed at 800 lb. to 1,000 lb.

For strict preventative measures, all of the bulls sold from 44 Farms are BVD-PI tested. So far, there has not been one positive animal found.

Mike estimates 50% to 70% of the BVD-PI cattle never make it to the butcher. “That’s the only thing we can do with them—have them isolated, finish and slaughter them,” he says.

In addition to the backgrounding operation, the Betscharts have 70 head of cows. All of the calves are BVD-PI tested, and the family is gradually adding new genetics into the herd with purchased females that are tested.

Testing at the seedstock side is also important in the BVD disease prevention process. At 44 Farms in Cameron, Texas, all 1,295 Angus bulls sold last year were screened for BVD-PI.

“We feel it is definitely a positive thing to do on the seedstock side, not only for perception but to identify and try to eliminate PI calves,” says Doug Slattery, 44 Farms chief operating officer.

For nearly three years, 44 Farms has used Gold Standard Labs for BVD testing. During that time, there has not been one BVD-PI calf found.

“We feel strongly about testing, especially on the cattle we’re merchandising,” Slattery adds.

As part of Slattery’s duties, he purchases calves back from bull customers, which are then fed out for 
44 Farms’ branded beef program, 44 Steaks. If the calves are BVD-tested, he’ll pay a higher price just to reduce the risk at feeding, he adds.

“That’s the biggest issue you run into in the feedlot, and we definitely feel [BVD-free calves] are worth a little more,” Slattery says.

Ron Hinrichsen, national sales manager for Gold Standard Labs, agrees calves tested for BVD-PI should command more dollars at sale time. Hinrichsen points to 2013 data from Superior Livestock on calves sold through video auction.

“After the cost of doing the test on a 600 lb. calf, there is a $14 per head return to those producers who are testing calves for BVD-PI. Buyers were looking for BVD-free calves based off of that data,” Hinrichsen says.

Gold Standard Labs utilizes pooled sampling with a real-time Polymerase Chain Reaction (PCR) test to reduce the cost to producers. Ear notch samples are pooled at the laboratory into groups as large as 25. If a positive shows up, the lab tests each individual sample. Testing costs $3.50 per head with no additional cost for an individualized retest to confirm BVD-PI positive status.

Hinrichsen believes testing is a “simple biosecurity measure for any incoming cattle” that will help reduce the incidence of BRD and, in turn, decrease antibiotic use.

“I think it is important for people to know that these cattle can look normal, they can perform normal, and they can still be a BVD-PI carrier,” Hinrichsen says. “It is important for producers to test their cattle because it is inexpensive and the return that it adds to their investment is worth it.”

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