Have you ever heard of “BVD-PI”? It stands for Bovine Viral Diarrhea-Persistent Infection, and can be devastating in a herd since not only is it fatal for a calf, but that calf can spread it to the rest of the herd. Who do you test? All calves whether born alive. aborted, or purchased; all cows whether pregnant or open, and especially those with a BVD-PI positive calf; all bulls. In fact, your whole herd should be tested. An ear notch sample is the best since it will not contain any maternal antibodies, can be tested by multiple methods, and can be shipped “dry” to the lab.