COLUMBIA, Mo. – Bovine virus diarrhea is an old disease in the cattle industry that has taken on a new twist with the discovery of the persistently infected condition.
According to Eldon Cole, livestock specialist, University of Missouri Extension, the condition is a hot topic now with the discovery of a new testing procedure of animals for the condition.
“[Bovine virus diarrhea] affects both the cow-calf and post-weaning sectors of the industry. Estimates show one infected animal in a cow herd can cost $15 to $25 per cow, per year,” Cole said.
After weaning and the animal goes to a feedlot, costs will escalate.
Outbreaks. Cole says many producers have been vaccinating for bovine virus diarrhea, or BVD, as part of a sound immunization program, but once in awhile troubling outbreaks occur.
“The virus can cause immune suppression, respiratory disease, infertility and fetal infection. The latter can lead to early embryonic death, abortion, birth defects, stunting or the birth of a [persistently infected] calf,” Cole said.
How it happens. The persistently infected condition occurs when susceptible pregnant cows are exposed to BVD virus during mid-pregnancy and the virus passes from the dam to the fetus.
That persistently infected animal will remain a shedder the rest of its life.
“If the infected fetus survives to term it will always have a large amount of the virus in it which means it can secrete the BVD virus throughout its life,” Cole said.
It’s estimated 20 percent to 50 percent of all persistently infected calves die before weaning.
A few appear to remain normal, but can infect others they come in contact with.
Testing. “Testing for the [persistently infected] condition with a tissue test taken early in life can reveal who in the herd has [persistently infected] and who does not. The test is called an ‘ear-notch test’ because tissue is normally taken from the animal’s ear,” Cole said.
Rates. The incidence rate of persistently infected is fairly low in herds in the U.S.
Estimates are that 4 percent of the herds in the U.S. have at least one persistently infected animal.
Some states have adopted a voluntary BVD-control program.
“This is attractive to seed stock producers who can assure their customers that bulls and females purchased from them should not be shedders of BVD,” Cole said.
The logic. Cole recommends cattle producers visit with their veterinarians about the logic of persistently infected testing within their herds.
Currently, tests will cost about $3.50 to $5 per head depending on the number of animals tested at one time.
In addition to possible testing, Cole says a vaccination schedule using a modified-live BVD vaccine is suggested along with appropriate biosecurity practices on newly purchased cattle.
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