Test to eradicate disease in cows
Adelaide researchers are developing a test to help eliminate 'hidden carriers' of bovine pestivirus and say preliminary results already show signs of promise. The reproductive disease costs Australian farmers livestock and thousands of dollars each year.
Source: PM | Duration: 3min 27sec
ASHLEY HALL: Much of the time it flies under the radar, but when bovine pestivirus strikes, it can wreak havoc in an otherwise healthy herd of cattle. The reproductive disease costs Australian farmers livestock and thousands of dollars each year.
So Adelaide researchers are developing a test to help eliminate 'hidden carriers' of the infection, and they say preliminary results are already showing promise.
Caroline Winter reports.
CAROLINE WINTER: Five years ago Malcolm Crossman's herd was struck down by bovine pestivirus, also known as bovine viral diarrhoea or BVD.
MALCOLM CROSSMAN: It was quite severe. They call it an abortion storm, that was the reality of we'd faced and it was because we had a benign herd that hadn't been exposed to pestivirus previously.
CAROLINE WINTER: It turned out, a bull the South Australian dairy farmer bought was a carrier of the disease and the animal had infected his otherwise healthy female cows. As a result 50 calves died.
There was also a hit to the farm's bottom line.
MALCOLM CROSSMAN: We came up with a figure of $140,000 loss due to lost production in milk, increased somatic cell counts because of the pressure on the cows, and therefore we lost premium payments and quite a lot of our milk and the other thing that was probably fairly critical to all of this was the loss of potential breeders for the future.
SASHA LANYON: We estimate BVD costs an infected heard at least $5,000 a year and we extrapolate that out to a figure of about $5 million for South Australia and closer to $50 million Australia-wide.
CAROLINE WINTER: Adelaide University researcher Sasha Lanyon is part of a team trying to address the problem. She says more than 80 per cent of herds and just over half of all cattle have been exposed to the disease.
Bovine pestivirus in normally healthy cattle is fairly mild. Most recover quickly after being infected and are then immune for life. But Ms Lanyon says problems arise when calves are infected in the womb.
SASHA LANYON: The virus can kill the calf and will see an abortion but it can also live and that calf can be born what we call persistently infected, now these persistently infected animals can be quite unhealthy animals but they can also be fairly healthy. But they're little virus factories and they got out and they spread and maintain BVD in the cattle population.
CAROLINE WINTER: As part of the trial, 17 heifers were infected with BVD, after a persistently infected animal was introduced to the herd. Blood and other samples have been taken from the cows and calves which survived. Now infection and antibody levels are being analysed to detect differences between carriers and non-carriers.
SASHA LANYON: We're hoping that this test will allow us to fill the last gap we have in BVD diagnosis which will allow us to very effectively identify and remove these animals from the population and drastically reduce the prevalence and therefore the impact of BVD infection.
CAROLINE WINTER: Wayne Hall from Meat and Livestock Australia says while the disease is prevalent, it's not always obvious when an animal is a carrier.
WAYNE HALL: The test is designed to actually give producers another tool to manage the risk associated with the biosecurity of their herd. So what it might mean is that if I've got a herd of animals that haven't been exposed before, they're naive, they have no inbuilt protection, and I want to introduce some pregnant animals what it does give me the opportunity is to actually test those animals before they come in.
CAROLINE WINTER: Results on this study are due in a few months, with plans for a fullscale trial next year.
ASHLEY HALL: That report from Caroline Winter.