I had a request at the Springdale Sale Barn for an article two weeks ago. Several of the buyers requested that I write about PI-BVD again. I told them that I had already written three articles about it previously, but they think it is too important not to write about, again.
PI-BVD stands for Persistently Infected Bovine Viral Diarrhea, a viral infection of cattle. Due to the nature of this disease being viral, we do not have a cure, only prevention. The prevention is in vaccination. BVD virus causes a respiratory syndrome, abortion, hemorrhagic disease syndrome and mucosal disease. It can also depress the immune system like HIV and AIDS. The PI-BVD form is when a fetus is infected with the street virus between day 40 and 135 of the gestation cycle. At day 135 the fetal immune system starts to develop. The BVD virus is already in the fetus and the immune system now recognizes the BVD virus as part of the fetus. Due to the nature of the virus it can and will cross the placental barrier in the cow and infect the fetus.
Now we have a pregnancy that is a carrier for BVD virus. The cow will go ahead and have a normal pregnancy and deliver a live calf. This carrier calf is born and has BVD virus growing in its body. This calf will shed 10,000 times the amount of virus that an animal dying of BVD will shed. This shedding happens every day of this calf’s life in that amount. Now, due to the fact that this calf was infected before its immune system was even developed, there is no vaccine or anything on this earth that will stop this form of BVD.
Now, even if we vaccinate our whole herd against BVD properly, this calf is bombarding each animal with the BVD virus. How does our vaccine have a chance? These viral particles are coming from every breath, cough, sneeze, urination and defecation of this calf. With the immuno-suppressive aspects of BVD virus you can see how the health of the whole herd is affected.
Sixty-five percent of these PI calves will die of BVD by the time they are either 432 days old or weighing 1000 pounds. The other 35 percent will grow up un-noticed and get into our herds and continue spreading BVD virus. You can have a positive PI calf born to a negative cow, but every calf born to a positive PI cow will be a positive PI calf.
The test runs around $4 per animal. If we come in and test all your calves and find one positive calf, we will then only test that calf’s mother. This eliminates testing all the cows but will give us a clean negative herd. Most of the buyers at the sale barns are testing on the other end, after the calves are delivered to the feeder or stocker. I have seen PI tested negative calves sold here and they brought $0.02 more per pound. On a 500 pound calf that means a total of $10 more gross dollars and a net of $6 per calf. Now, if you were selling 100 calves tested negative for PI-BVD weighing only 500 pounds, this would mean a net of $600 more value for your sale. This would be like gaining another calf.
