Pestivirus is a national beef challenge, says vet

In a colourful address to the forum, Enoch Bergman, from Esperance and a past president of Australian Cattle Veterinarians, urged growers to test the immune status of their herds for BVDV (bovine pestivirus).

“If you can’t measure it, you can’t manage it,” he said.

Tests for the disease, which he said was widespread across the country, were accurate and cheap compared with the potential losses from abortion and weak and deformed calves, he said.

BVDV was almost exclusively spread by “persistently infected” (PI) animals (carriers of the disease), Dr Bergman said.

Not all PI animals “looked like hell” and long-term management of the disease rested on getting rid of them, he said.

PI animals can be identified with an ear notch test and besides BVDV, they could potentially carry a host of other diseases.

PI animals shed enormous amounts of the BVDV virus and transiently infected most cattle they had contact with, Dr Bergman said.

While these transiently infected animals developed an immune response and recovered over time, the disease could potentially cause heavy calf losses.

Dr Bergman said he would like to see “everyone” test a sample (around five per cent) of their heifers and cows for BVDV before joining.

While Australian producers have access to one effective vaccine against BVDV (Pestigard), there was little point vaccinating if they already already had immunity to the disease.  

“Vaccination is an insurance policy, not a solution (to the disease),” he said.

If a non-immune cow was exposed to BVDV during mating or pregnancy, she may fail to get in calf or lose the calf.

The BVDV virus will cross the mother’s placenta to her unborn calf and if the embryo is one to four months old and survives, that animal will become a PI and can’t ever get rid of the disease, Dr Bergman said.

A PI cow will always have a PI calf.

Dr Bergman urged producers to get rid of BVDV out of their herds by eliminating PIs and keeping the disease out through strict biosecurity and constant vigilance.