A new test for detecting tuberculosis in cattle began trials in Wales on Friday.

It is hoped the blood test will be more effective in clearing farms of the bovine TB.

More than 650 farms are expected to take part in the trials of the Gamma Interferon blood test over the next two years.

Farmers have long blamed badgers for the disease

It will be offered to farmers whose animals already have TB and are under restiction.

Conventional tests will continue to be carried out even if herds are taking part in the trial.

The study will show whether the new test - said to be more sensitive than the present skin test - is more effective in picking up signs of the disease.

The eventual aim of the exercise is to speed up the process of clearing bovine TB from farms.

Skin test

Critics of the test have, however, have argued that it is too sensitive, and that some cattle which do not have TB might react to it.

Although TB is not a new disease in cattle there has been a steady increase in the number of cases, and it is hoped the pilot project will offer some solutions.

All cattle herds in Wales are routinely blood tested for TB.

The traditional test - which will continue, even on the trial farms - is a skin test whereby cattle are injected with a small amount of TB.

Foot-and-mouth was a devastating blow to farms

Herds are-re-visited within three days to see if any cattle have "reacted" to the skin test.

The gamma interferon test will only be offered to farms which have already got TB.

Farmers will be asked if they want to take part and will then be split into groups for research purposes.

The aim of trial is to see whether the new test, used iwith the existing one, will succeed in swifter detection of TB and so a faster clear-up time.

The Welsh Assembly government will have to pay compensation to farmers if any animal is slaughtered - whether affected by TB or not.

TB - the facts

No public health risk Different strain in cattle known as Mycobacterium bovis Infection constantly present in cattle Around 30 people treated each year Symptoms similar to human form

Farming unions have been pressing for these trials for some time and have welcome the start of the study.

Earlier this year, the UK government played down reports that an outbreak of TB in cattle in north Wales could be worse than the foot-and-mouth outbreak.

A Welsh vet had warned in April of a "serious" situation developing in Denbigh.

But animal health minister Elliot Morley said the comments by North Wales Divisional Veterinary Manager David Pugh were misleading.

He added that TB in cattle was confined to a small percentage of the UK national herd.

Ten beef cattle at a farm near Denbigh - an area previously clean of TB - were destroyed and tests are under way on 50 farms in mid Wales with the results expected within four days.

In 1997, 55 Welsh herds were hit by TB, but that rose to 150 annually by 2000, according to UK Government figures.