Joint project launched to eradicate Johne's disease

A CONCERTED campaign to identify the factors causing paratuberculosis -more commonly known as Johne's disease - in cattle and sheep has been launched by the Scottish Agricultural College and the red meat industry promotional body, Quality Meat Scotland.

The disease costs Scottish farmers millions of pounds a year in losses and impaired performance and is notoriously hard to diagnose and control. The Paraban project will involve the whole industry, from farmer and vet to meat processor and supermarket, with the aim of developing more effective diagnostic and treatment techniques.

"Johne's is a 'hidden disease' which is ultimately fatal," said SAC vet Professor George Gunn, who is co-ordinating the project.

"The number of animals showing clinical signs in a herd is the tip of the iceberg. It is estimated that if you have an animal with clinical signs in the herd, you could have another ten to 25 animals with sub-clinical infection."

He was speaking at Glenbervie Home Farm, Stonehaven - owned by the Macphie of Glenbervie bakery ingredient manufacturers - where farm manager John Lohoar has adopted best practice for ten years without totally conquering the disease.

Glenbervie is one of nine farms - from Caithness to Cumbria - which have agreed to become demonstration farms to exchange knowledge of the disease throughout the production chain and explore the interaction of all factors limiting its control.

The 200-cow Glenbervie Aberdeen Angus herd has been closed since 1992, except for stock bulls, and operates a strict policy of culling all females that test positive for the disease and their progeny.

More than 18,000 has been spent on a testing programme and 24,000 on fencing to avoid infection from neighbouring cattle or from ditches. "Our aim is to eliminate the disease," said Lohoar. "We keep thinking we are getting on top of it, with the number of positives down to two or three a year, then we suddenly get a spike of cases for no discernible reason."

The disease is usually caused when calves or lambs ingest feed or water contaminated with faeces. It never leaves the animal, but can remain sub-clinical for several years before clinical signs appear. These include weight loss, reduced milk production and diarrhoea, but production performance is also reduced in cattle with sub-clinical infection.

The Paraban programme hopes to identify the most cost-effective approaches to controlling Johne's disease, including blood and faeces testing and post-mortem testing at the abattoir.