Milk vat gives disease alert

01-10-2009 | Not Specified

Farmers can now detect the presence of a disease which has the potential to severely dent farm profitability, and monitor a herd's exposure to it, from the milk vat.

BVD (bovine viral diarrhoea) is a highly infectious viral disease of cattle silently present in 30% of New Zealand dairy herds.

The disease is spread through body fluids and excretions damaging cattle health, fertility and productivity, sometimes resulting in death.

Farmer co-operative Livestock Improvement (LIC) has developed a new monitoring pack that will allow farmers to monitor their herds' BVD status every year in spring and autumn without the hassle of collecting blood or tissue samples.

The advantage of vat testing is simplicity. There is no need to collect test samples, as LIC reuses samples already collected by the dairy company.

LIC's tests are accurate for herds of all sizes so herd splitting to obtain multiple samples is not needed.

LIC's Diagnostics Manager, Geoff Corbett, says the new screening method combines two tests.

One shows the level of the herd's exposure to BVD infection (the antibody ELISA test) and one that identifies whether there is an infected cow milking by detecting the BVD virus presence in the milk (the BVD PCR test).

Corbett says the result contains a trend analysis which will provide more information than the traditional single test blood or tissue sample normally conducted twice during a season.

"The key to managing BVD disease is the identification and elimination of persistently infected (PI) disease carriers as well as taking biosecurity measures to prevent the reintroduction of the disease to the herd."

"If a pregnant cow becomes infected with the BVD virus during the first half of pregnancy it can result in the birth of a live calve that remains persistently infected (PI) with the BVD virus throughout its life."

He says PI calves will never get rid of the disease. They tend to be sickly and spread vast quantities of the BVD virus to susceptible cattle for their entire lives.

A major disease outbreak can reduce a replacement crop of animals by one-third or more through lower conception rates, early loss of pregnancies, abortions, birth defects and weak PI calves with low survival rates.

Early identification of the presence of PI animals means farmers can take steps to prevent a major disease outbreak.

"Studies have shown costs for the average herd infected with BVD is around $7000 due to the loss of herd replacements and high levels of animal treatments - and a major BVD outbreak can cost farmers $90,000."

Corbett says the new BVD monitoring pack provides peace of mind for dairy herd owners by providing on-going surveillance and an early warning of infection.

  Printable View