Page 20 - Te Mania Angus 2021 Catalogue eBook

WHY BVD / PI TEST? RECESSIVE GENETIC CONDITIONS

All bulls offered through the Te Mania have been screened for persistent infection (PI) for the bovine viral
diarrhoea virus.

The screening provides Te Mania bull buyers the utmost confidence that their new seedstock are not “carriers”
of the BVD virus.
For cattleman, 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 the
virus circulating in their blood and other fluids and they shed the BVD virus continually.
A PI calf is “created” during pregnancy when the BVD virus from an infected dam’s bloodstream crosses the
placental wall to her foetus during the first part of gestation. This is the ONLY WAY a PI animal is created.

Foetal infection can lead to foetal 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. Id a calf is not a PI at birth it can never
become a PI.
While uncommon, PI calves can grow to adult age without any outward signs of the BVD 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 into contact with.

Immunising cattle herds with the 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 by vaccination to its herd mates.

The cost of at least one PI animal in a commercial beef breeding herds has been reported to range from $14-
$24 per cow per year in reduced reproductive efficiency alone. Research also indicates the probability of initial
treatment of respiratory disease is 43% greater in cattle exposed to BVD-PI cattle in the same mob or feedlot
pen.

Therefore the cost of the BVD virus is too great to leave to chance
That’s why we recommend all cattle entering your herd – including your new bulls must be screened for the
BVD virus before they enter your operation.

Here are some other key points:
• All open heifers purchased should be screened for BVD-PI status well in advance of breeding
• Purchased 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 all new crop calves in advance of breeding to avoid exposure of a pregnant cow by a PI calf
• Cows do not need to be PI tested unless they have a PI calf
• If an animal tests negative for the BVD-PI status there3 is not need to ever retest that animal
• PI animals should be isolated from the herd and culled immediately
• PI surveillance should include sampling and testing of as many aborted foetus’, stillborns and pre-
weaning deaths as possible
These are some guidelines to help minimise the effect BVD can have on the health
of your cow herd and the financial implications that this serious virus can create.

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