Vigilance is key with Johne’s disease, NI expert
“Johne’s disease is often described as the odd one out in terms of infectious diseases on farms. This is due to Johne’s impact on trade between countries.” This is the view of Sam Strain, who is programme manager for Johne’s disease at Animal Health and Welfare Northern Ireland.
According to Strain, who is speaking today at Animal Health Ireland’s National Conference, Johne’s disease is currently one of the major diseases on farms across the island of Ireland. “It currently affects 21 per cent of dairy herds in Ireland. With three per cent of cattle within these herds affected and the situation is much worse in Europe with infection rates as high as 50 per cent found.”
“Ireland has been sheltered historically, due to the fact we are an island and this has sheltered us from the disease,” Strain noted. “However this has certainly changed. In the post quota era it is likely there will be more movement of livestock between countries. The island of Ireland has no framework in place to deal with Johne’s diseases, which is in place in other countries; this could leave us at a competitive disadvantage.”
Strain explained that infection rates are lower in beef herds. “Studies have found eight per cent of beef herds infected. This is probably a reflection of different production methods and systems. Typically the calves are treated differently on both systems. There could also be a genetic component to the diseases.”
Future Irish framework for dealing with the diseases involve three components, Strain added.
“The first being annual testing. This is done via a blood or milk test. The current tests sensitivity is quite poor. It can miss reactors. The second component is an on-farm risk assessment. This would involve an AHI-trained vet giving diagnosis and interpretation of results. Positive reactors should be culled. Identify on farms those practices that are most risky in terms of the spread of diseases and management practices that might mitigate these issues. The third component is herd categorisation. This will endeavour to identify Johne’s free herds comparing them to those who are not free.”
In Strain’s view, the crucial thing to get across to farmers is calf hygiene. “Prevent calves being exposed to cow dung is key,” he said. “We plan set up a pilot programme that will be reviewed and evaluated. Herds carrying out best practices reap benefits.”
The View from Australia
Also speaking at the event in on the issue of Johne’s is David Kennedy who is former national co-ordinator/technical advisor to the Australian Johne’s Disease Programme.
“Johne’s became evident in Australia in the 1920s. But it didn’t become common until the 1980s and 1990s. It became especially prevalent in the southeast of the country in dairy herds. But it has also been an issue in the beef industry”, according to Kennedy.
On the Australian Johnes programme, Kennedy explained: “We started in the 1995 to deal with the problem in the southwest and to stop its spread to the northern parts of the country. States such as Queensland are protected. When outbreaks occur, we try to stamp it out with a much more aggressive approach in the north of the country because the beef industry in the north needs to maintain its image of being a healthy exporter. Especially when trading with Asia.”
On the differences between dairy and beef, he outlined: “The risks are quite different, generally production methods are different. Beef animals are out on pasture, largely in extensive situations. Calving is not done in tight groups, thus there is lower prevalence in this sector.”
According to Kennedy: “We found in Australia that testing and culling alone was not usually effective in solving the problem. A regular risk-assessment approach focusing on management practices is important.”
He added: “The emphasis has to be more towards the calf. Better calf-rearing, hygiene in the calving area, not pooling colostrum. A significant change over the period has been that the number of dairy herds has halved yet the number of cattle has remained stable
“Infection has been seen to spread with movements so we ask farmers to manage their herds as if do have Johne’s.”
Kennedy concluded:“The industry in Australia takes on much of the burden of dealing with the diseases. Producers take a lot of the costs. The authorities focuses more on communication programmes and harmonising systems of controls between states.”
Pictured: Calves on outdoor pad. Photo O’Gorman Photography. According to NI animal health expert Sam Strain, the crucial thing to get across to farmers is calf hygiene
The Animal Health Ireland National Conference is taking place today.