BVD and persistent infection (PI) continues to receive a great deal of attention from veterinarians, researchers and producers.BVD is a very complex disease and has been the focus of many studies for the past 60 years.Cattle that are persistently infected help to constantly spread the disease to other cattle and create more persistently infected cattle.
The only way cattle can become persistently infected is to be born that way.The fetus is infected with BVD between days 40 and 120 of gestation.Since the fetus’ immune system is not functional at this stage, it accepts the virus as a normal part of its body and becomes a virus producing factory, shedding BVD virus to herdmates or penmates.
Drs. Bill Hessman and Dave Sjeklocha are feedyard consulting veterinarians from the HaskellCountyAnimalHospital in Sublette, Kansas.Along with Dr. Tim Murphy, a feedyard nutritionist from Dodge City, Kansas, they conducted one of the largest BVD studies to date.Hessman explains: “There were several small studies that indicated that PI cattle had a detrimental effect on morbidity and mortality, but none that really addressed the performance issues.In 2003, we conducted a small study (approximately 2200 hd) that revealed that the true costs of having a PI in the pen were not necessarily related to just morbidity and mortality – performance is the real difference maker.”Cattle were PI tested upon arrival in the feedyard and the pens that had a PI animal in them were identified and the PI animal was left in the pen. Then, the cattle were followed to slaughter.In that study, the PI positive pens were simply compared to the PI negative pens.It was found that having a PI animal in the pen resulted in an increased cost of gain and mortality of over $7.00/cwt across the pen!
Extrapolated out, this amounted to $36.05 per head in the feedyard! While these veterinarians found this interesting, they weren’t convinced that the whole story had been revealed.They felt more research was needed.
In 2004, Hessman convinced Roy Brown and Ron Shortridge of Cattle Empire Feedyards near Satanta, Kansas to help sponsor a study to further explore the impact of BVD.Brown and Shortridge responded by committing 20,000 head of cattle and an entire starter yard to the study. “Cattle Empire deals with high risk calves from the southeastern United States and they had recently built a 10,000 head starter yard.This was a unique opportunity to use an uncontaminated facility to look at the effects of PI cattle in several different scenarios,” says Sjeklocha.
Seizing the opportunity, Hessman, Sjeklocha and Murphy developed a broad scoping study in which all cattle were PI tested using the Antigen Capture ELISA (ACE) test.According to Hessman, “The ACE test has proved to be more accurate than PCR and just as accurate but quicker than IHC.”Hessman built a laboratory addition to his clinic in order to run the ACE tests.
At initial processing, all cattle going on to the trial had an ear notch sample taken and tested at Hessman’s laboratory.The study tracked several parameters, some of which included PI prevalence rate, effects of leaving a PI animal in a pen, effects of having a PI animal next door to a pen of “clean” cattle, effects of removing a PI animal from a pen and the effects of having no PI cattle in the pen and keeping these “non-PI” cattle completely segregated from any PI cattle.These researchers found that the PI prevalence rate (in 500 lbs. southeastern calves) was 0.40% (4 PIs per 1000 hd).“This may not sound like many, but the effects of one PI animal are far-reaching,” says Hessman.“This PI prevalence rate has proved to be fairly accurate, as our laboratory has tested well over 600,000 head and the prevalence rate is a steady 0.40%.At this rate, if a feedyard has pens with 250 head capacity, chances are good that there is a PI in every pen,” adds Sjeklocha.
What is the cost of having a PI animal present at this prevalence rate?This study revealed that these costs add up to over $40.00 per head in the yard in just the first 60 days in the starter yard!
As word of this study spread, many of Hessman’s clients asked to get their cattle tested.Hessman could see that the laboratory needed to be a separate business from his feedyard consulting practice, thereby creating Central States Testing, LLC.“Central States Testing is the largest provider of BVD PI testing in the United States.We have the largest database on the effects of BVD and we continue to conduct research on BVD to the tune of over 20% of our testing revenues are spent on more studies so we can continue to be the leader in BVD information for our clients who test with us,” states Hessman.“The work we have done here will most likely have a huge positive impact on the beef industry as well as the dairy industry,” adds Sjeklocha, “It has been exciting to study the disease and we look forward to continuing to study it.”
For More Information contact Central States Testing at 620-675-8640