What is it?
BVD is a viral disease of cattle that can cause many problems in a herd. Although the name would make you think diarrhea is the major problem, in most herds infertility is the most common and costly because it can go undiagnosed. Other problems caused by BVD include pneumonia, abortions, still births, weak or deformed calves and immunosuppression.
BVD in Calves
> Calves with low immunity (non-vaccinated, vaccinated but stressed) are susceptible
> Pneumonia and/or diarrhea can occur
> Immunosuppression can lead to other disease problems
> BVD is part of the cause of Bovine Respiratory Disease Complex in feedlot calves
BVD in Cows
> Cows rarely become sick
> Exposure during breeding season
• Early embryonic death
> Exposure during first half of gestation
• Persistently infected calf
> Exposure during second half of gestation
• Stillborn calf
• Weak calf
• Deformed calf
Persistently Infected Calves (PIs)
> Fetus becomes infected with BVD during first half of gestation
> Calf is born
• Can be healthy and grow normally
• Can be sick and poor-doing
> PI calf sheds very high levels of virus in all bodily secretions and exposes cows and calves
> PI calf exposes cows to BVD and causes problems listed above
> More PI calves are created
• Next year same problem
>Now the virus stays in a herd from year to year
Do you have it?
Since the problems listed previously can be caused by many things, producers should consult their veterinarian about other potential management factors and diseases. BVD testing may not be the first thing to look for or try to correct. To test for BVD, ear notches or other skin samples should be tested. Fortunately, newer testing methods pool several samples together to screen a herd for BVD, which can greatly reduce the cost associated with testing. If a pooled sample is positive, individual samples will be tested by the lab to find the infected animal(s). Testing should be done as soon as all calves are born and before breeding season starts. If you wait until breeding season has already started, you will have to test again next year. (New PIs may already be incubating in cows that will give birth the next year.)
Which animals should be tested?
• All calves
• All bulls
• All replacement heifers
• Breeding age cattle that do not have a calf being tested
A chute-side screening test is now being evaluated for use in the feedlots to pick up potential PI calves on arrival. Those calves testing positive are isolated until confirmatory tests are done. This test may eventually be available for on-farm screening and testing of herds.
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