BVD, Genetic testing & DNA Profiles
All bulls offered through Midland have been screened for persistent infection (PI) with the bovine viral diarrhea (BVD) virus. This screening provides the Midland buyer utmost confidence that their new seedstock are not “carriers” of the BVD virus.
For cattlemen, the primary concern of spreading the BVD virus is through PI cattle; with transiently (or temporarily) infected cattle considered a less important source of the disease. PI animals are very efficient transmitters of the virus. They usually have a very high and virulent amount of virus circulating in their blood and other fluids; and they shed the BVD virus continually. A PI calf is “created” during pregnancy when BVD virus from an infected dam’s bloodstream crosses the placental wall to her fetus during the first part of gestation. This is the only way a PI animal is created.
Fetal infection can lead to fetal death, the birth of a PI calf, or the birth of a normal calf. It’s important to note that a calf born BVD-PI will always be a PI animal. If a calf is not PI at birth, it can never become PI. While uncommon, PI calves can grow to adult age without any outward signs of BVD virus infection. The virus is perpetuated when these PI animals – bulls or heifers – survive past yearling age and enter the breeding herd. PI heifers or cows that conceive will always produce a PI calf. A PI bull has the dangerous potential to effectively and efficiently spread the BVD virus to all cattle he comes in contact with.
Immunizing cattle herds with appropriate vaccines to protect against transient infection should be the first consideration in a herd biosecurity program. But, given the right conditions, the tremendous amount of virus secreted by a PI calf can overwhelm a level of immunity provided its herd mates by vaccination. The cost of at least one PI animal in a commercial beef breeding herd has been reported to range from $14-$24 per cow per year in reduced reproductive efficiency alone. Research at West Texas A&M University found feedyard PI prevalence to be about 0.17% (1.7 PIs per 1,000 head). This research also indicates the probability of initial treatment for respiratory disease is 43% greater in cattle exposed to BVD-PI cattle in the same pen or an adjoining pen. Therefore, the cost of BVD virus infection is too great to leave to chance. That’s why we recommend that all cattle entering your herd, including your new bulls, be screened for the BVD virus before they enter your operation.
More key points:
- All open heifers purchased should be screened for BVD-PI status well in advance of breeding.
- Purchased bred heifers or cows with an unknown BVD-PI status should be kept separate from the resident herd until their PI status can be confirmed by first screening their calves.
- Screen the all new crop calves in advance of breeding to avoid exposure of a pregnant cow by a PI calf.
- Cows do not need to PI tested unless they have a PI calf.
- If an animal tests negative for BVD-PI status, there’s no need to ever retest that animal.
- PI animals should be isolated from the herd and should never enter commerce.
- PI surveillance should include the sampling and testing of as many aborted fetuses, stillborns and pre-weaning deaths as possible.
- All “non-biological” pairs should be screened for PI status – this includes “recipient” cows.
- Screen all cows that lose a calf and a tissue sample not obtained from the calf.
We submit registration numbers of all sale lots to each respective association. They identify animals who need tested. Genetic defect carriers (AM, NH, OS, M1, AND DD) are ineligible. Genetic carries of OH are eligible, no requirement for testing. If bulls were tested prior to arrival, please provide the results.