Moving stock? Think about your Theileria risks
Tuesday March 10, 2015
Industry body DairyNZ is warning farmers to assess the risks to their herds from the tick-borne disease Theileria if
they are moving stock this autumn and winter.
DairyNZ veterinarian and technical policy advisor, Nita Harding, says stock out at grazing such as heifers that will be
coming onto the farm could pose a risk, or be at risk of Theileria, depending on the situation on farm.
Nita says farmers can help the industry and veterinarians manage and prevent the spread of the disease if they are
moving cattle between Theileria zones this season.
"Pregnant cattle are at the highest risk. Other stock classes appear not to be as susceptible," she says.
"To assess your risk you need to understand your current level of risk where you farm and the risk of the area that the
cattle are moving from or to. We've subdivided the country into three general zones, based on our current knowledge of
tick distribution and farms on which the disease has been confirmed," she says.
"Essentially we have stable, unstable and free areas - and they equate to high, moderate and low risk areas for
Theileria. High performing animals from free and unstable areas moving into stable areas are at particularly high risk.
We're strongly recommending that farmers shouldn't bring in pregnant heifers and cows from tick free areas into stable
areas without seeking veterinary advice. Sharemilkers who are forming their herds or farmers undertaking conversions and
forming new herds need to take particular care."
If you are buying in replacements or are building a herd from multiple sources, it is a lot more complicated to assess
the risk of Theileria to your farm, she says.
"Remember there could be multiple diseases that could pose a risk to your farm so it's important to talk to your
veterinarian and do a bit of risk assessment and management planning."
Franklin Vets managing director Mark Hosking says there is a movement risk tool on the Franklin Vets' website
(www.franklinvets.co.nz ) which farmers can quickly use to see what risk they may face.
There is also advice on DairyNZ's website www.dairynz.co.nz/theileria and the New Zealand Veterinarians' Association website www.nzva.org.nz
"We've dealt with a lot of cases in our area so we have worked to help others across the country to understand the
disease. For people who are moving stock into areas with ticks, we would strongly advise that they carry out blood tests
to determine if the animals being moved have been exposed to the parasite. If they have been exposed then there should
be relatively little risk of them developing clinical disease. However if they haven't come across the parasite before
then they will be at a high risk of breaking down with clinical theileriosis.
"If you are moving animals from one property to another, it is paramount that you try to assess the risk you face of
running into problems," says Mark.
"Farmers should avoid exposing naïve animals to infected ticks six to eight weeks prior to calving/peak milk production.
Most naïve dairy animals arrive into infected areas in May/June, two months prior to the major stress of calving and
milk production," he says.