Pressing home the decimating effects of Johne’s disease at Beef Expo, George Caldow, SAC, discussed its financial and physical impacts and eradication methods.
With 5% of adult herds confirmed with the disease every year, Johne’s could reduce productive life by two-thirds, he said.
“This chronic disease, caused by M paratuberculosis (MAP), an organism related to TB, causes severe diarrhoea and wasting. In the UK the prevalence could be close to 50% in herds.
“Because of its spread in faeces the disease is difficult to control. Animals most susceptible are young calves, infected with Johne’s during pregnancy, by colostrum or during the first weeks of life.
“During pre-clinical stages animals can test negative for several years, as only small amounts of MAP are secreted. As animals get older they are more likely to test positive, as more MAP is shed. For this reason it is vital annual tests are conducted detecting the most infected animals before they become highly infected.
“National approaches to control by accrediting herds free of Johne’s, promoting biosecurity, advising on hygiene and husbandry and test and cull programmes are all ways to help eradicate the disease,” said Mr Caldow.
“More than 300 herds are accredited free from Johnes’, with a thousand herds part of a scheme.
“As breeding females are the main cause of spread, demand for Johne’s-free commercial females is important. With cost of accreditation ranging from £700 to £900 for a 100-cow herd, it is estimated that only 20 heifers will have to be sold to pay off.”