By Andi Anderson
Identification and removal of PI cattle:
BVD PI cattle are born with the BVD virus and shed virus particles everywhere they go for their entire life. They are the main source of BVD virus infection for other cattle. Identification and removal of PI cattle is critical to stop long-term survival of the virus.
Diagnostic testing:
Testing for BVD PI cattle is easy and inexpensive using the BVD ELISA test. The most commonly used sample is an ear notch skin sample. Blood (serum) can also be used although not in calves less than 3 months old. If the ear notch or serum test result is negative, that animal is negative for life and will never need testing again. Any BVD ELISA positive test result should be confirmed by first separating the animal away from the herd and then retesting a second ear notch or blood sample taken 3 weeks after the first sample. True PI animals will still be positive after 3 weeks while those animals with a short-term infection (transiently infected) will test negative on the 2nd sample.
The following testing strategies are recommended for cow/calf operations:
- Test all calves at an early age (at least 2 weeks old)
- If a calf is confirmed positive, test the dam
- If a calf is negative, the dam can be assumed negative and does not need to be tested
- Test any cow/heifer without a calf at her side
- Test all bulls and replacement heifers (purchased or raised)
Quarantine and test purchased pregnant females and, if negative, they can join the home herd. However, bear in mind that any of their unborn calves could be a PI and all calves must be tested at 2 weeks of age or older, the sooner the better. A better option is to calve out purchased pregnant females away from the home herd and test their calves for BVD virus prior to any mixing with the home herd.
Interpretation of results:
If a calf tests positive for BVD PI, it is important to remember that PI calves are considered defective and there is a legal, moral, and ethical obligation to either feed them out for personal consumption or euthanize and dispose of these animals without sending/returning them to commerce. Animals that test positive are not to be sold, given away, or transported without approval of the State Veterinarian.
BVD virus is a serious disease that can have a significant impact on cow/calf operations. By following the diagnostic testing strategies and interpretation of results outlined in this article, producers can identify and remove PI cattle from their herds and help to protect their herds from BVD virus infection.
Photo Credit: istock-simplycreativephotography
Categories: Ohio, Livestock, Beef Cattle