Awhile ago I wrote several articles about PI-BVD. This is persistently infected animals with BVD or bovine viral diarrhea. By being persistently infected means that they were infected while in uteri. The street virus attacks the cow while she is between 45 days and 120 days of gestation. This virus is so small that it will cross the placental barrier and infect the calf. Now at this stage of gestation the calf still has a lot of development to do. We have not even started the development of the calf’s immune system. Because of this non-development of the immune system, the virus is there when the immune system starts to develop. And since that is suppose to be a sterile environment, the BVD virus is recognized as part of the calf.
Now with BVD virus being recognized as part of the calf, the immune system of the calf says that BVD virus is normal for this calf. So, the BVD virus continually grows and sheds from this calf. We do know that a PI-BVD calf will shed 10,000 times the amount of virus that a normal calf dying of BVD will. If you have a calf like this in your herd, it will be shedding BVD virus everyday of its life. Your other animals may be protected but, they are getting bombarded with the virus everyday. The others in the herd could become immune compromised and catch a list of other diseases, such as pneumonia. We now know that this is what was causing the wrecks with stocker cattle, where they were having over 50-90 percent getting sick.
I was reading in Bovine Veterinarian about Superior Livestock Auction, where they have reported that a 600 pound calf certified tested negative for PI-BVD was adding at least $10.00 onto the profits of each calf tested negative. The overall numbers are gross premiums add on of $14.52. That is an added $2.42 per hundred weight added on as compared to cattle not tested. The cost of the test is about $4.00 per head, so the net gain in money is more than $10.00 per head.
The way calves are tested is generally by taking a baby pig pair of ear notchers and taking an ear notch out of the calf. This ear notch is then put in a special vial and sent to a lab. Normally results can be received back within 48 hours of sending the sample in. Yes, the cost is around $4.00 each.
With buyers willing to pay for this testing and certification I can’t see not doing it while we are putting them through the chute to vaccinate. I also recommend testing the calves first and not testing the cows. If we have a positive calf, then we will go back and test its momma. You can have positive calf born to a positive momma, but you can also have positive calf born to a negative momma. So, test the calves first and that will tell you if your cows have it. But, that doesn’t tell you anything about the bulls, so we do have to test them.
With a PI-BVD free herd, you need to advertise that you have that and command the extra money for it. And the buyers are paying for it, as evidenced by Superior Livestock Auction.
Dr. Tim E. O’Neill, DVM, owns Country Veterinary Service in Farmington, Ark.


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