Veterinarians want bulls vaccinated against a deadly disease to protect dairy herds but support for the move is guarded, writes Sue O’Dowd.
By SUE O’DOWD – Taranaki Daily News
Sue O’Dowd
Eltham vets Andrew Weir and Polly Otterson are promoting vaccination of bulls to combat bovine viral disease.
Dairy farmers are being urged to safeguard their herds against the devastating disease bovine viral diarrhoea (BVD).
Eltham Veterinary Services is offering tailor-made protection plans to about 100 farmers whose animals have no immunity to BVD and are most at risk of contracting it.
The facts
- Bovine viral diarrhoea, or BVD, occurs in cattle after close contact with infected animals.
- All body fluids contain the virus.
- BVD suppresses the immune system and causes fertility problems.
- BVD causes scouring, pneumonia and low growth in calves, which may be born deformed and weak.
- Calves born from infected cows may appear normal, but shed the virus in large amounts for their entire lives and are a major source of infection.
- Cows with BVD are prone to mastitis, their production falls, and their somatic cell counts rise.
Dr Polly Otterson and Dr Andrew Weir are promoting the message that bulls should be tested for BVD and vaccinated, although support from stock agents and bull sellers is guarded.
Dr Otterson said there was a long way to go to educate farmers about BVD, because of the prevalent view that “it won’t happen to me”.
Farmers needed to think now about testing and vaccinating, because cows were most vulnerable to pregnancy loss when bulls were introduced to the herd for mating, she said.
“Whether you have no BVD in the herd or heaps, it still pays to have the bull vaccinated.
“Testing and vaccinating every bull is a cheap way to give huge protection. Not having BVD is great, but if it comes into a vulnerable herd, it will hit it harder.”
While fewer than 1 per cent of bulls were persistently infected (PI) – born with BVD – the consequences of a herd infection were devastating, she said.
“The PI bull is like a house fire. The risk is small, but when it does happen, it’s hard to recover from.”
Vaccination consists of two shots a month apart, with the second shot a month before mating. An annual booster is required. Bulls would need the second shot by the beginning of October to be protected.
Dr Otterson said most Taranaki bull suppliers tested for BVD, but vaccination was less common.
She described buying bulls from the saleyards or small operators as risky. A bull that tested negative for BVD but was not vaccinated could become infected at the saleyards, she said. She favoured proof of BVD tests and vaccinations.
“But there needs to be consumer demand for it, so that farmers will not buy bulls without certificates.”
John Kelly, of John Kelly Livestock Ltd, said he supported bull testing and vaccination because he knew BVD could devastate farmers’ lives. He had clients who had lost 20 to 30 per cent of their young stock – their replacement cattle – to BVD.
“I recommend to my clients that they insist on testing and vaccination.”
He said he would like farmers to be better educated about the disease, because messages about it were inconsistent. He also believed professional graziers should require testing and vaccination before accepting cattle.
Bill Craig, of Stratford, who hires and sells bulls, said he tested and vaccinated for BVD because he had to. Of 1200 bulls he had just had tested, two returned positive tests and were culled.
This year Mr Craig lost eight to 10 calves after the virus occurred in his own Hereford herd.
Although bull seller John Washer, of Oakura, tests and vaccinates 500 Jersey bulls a year, at a cost of $20,000, he has never found a reactor.
“I have to wonder if I’ve been lucky, because I do know that people who have had BVD are decimated by it,” he said.
While somewhat sceptical of BVD’s incidence, he acknowledged that testing and vaccination were good insurance because of the disease’s crippling effect on dairy herds.
When BVD was eradicated, vets would no doubt find something else they wanted bull sellers to test for, he said.
Hurleyville bull supplier Bernie Fowler said BVD testing was cheap insurance. He tested and vaccinated all his bulls because most buyers wanted proof.
“But it’s down to the individual farmer to ensure the tests are done. If a farmer brings an animal on to his property, it’s at his own risk.”
Mr Fowler, who is wintering 450 bulls, said it was in his interest to be proactive in animal health.
Allied Farmers’ dairying co- ordinator for Taranaki, Kim Harrison, said astute breeders already tested and vaccinated their bulls, but some traders were put off by the cost. Increasingly, dairy farmers were demanding that bulls they bought were tested and vaccinated.
Dr Otterson said Taranaki had the lowest prevalence of BVD in New Zealand, with 11 per cent of dairy herds with an active or recent infection, possibly because herds here were smaller and relatively isolated.
Figures published in 2007 put the cost of BVD to the dairy industry at $44 million.
An outbreak last season cost an Eltham farmer more than $12,000 per 100 cows. It was caused by a heifer born on the farm three years ago and was introduced to the herd in March last year, when the cows were pregnant.