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Veterinary commitment essential for Johne's plan to succeed...

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01 January 2015, at 12:00am

RICHARD GARD attended the recent conference on JD where details of the new national management plan were outlined and heard both vets and farmers outlining their hopes for eventual control

THE commitment of the veterinary profession is essential if the proposed National Johne’s Management Plan is to succeed, a conference on the subject in November was told.

Feedback on the plan is required via www.actionjohnesuk.org by 18th January, with the finalised plan to operate from April 2015, following a formal launch. Training for veterinary surgeons is being planned by the British Cattle Veterinary Association, with the emphasis initially on dairy herds, moving on to control in beef herds.

Dairy UK and DairyCo combined to arrange the conference, which was chaired by Lyndon Edwards, an organic dairy and beef farmer, who chairs the Action Group on Johne’s.

Speakers provided information on the disease and outlined the hopes and ambitions for future control.

Professor Michael Collins (University of Wisconsin) explained that the US spent $118 million on a Johne’s programme but as the money diminished the recruitment of farmers fell. The producers do not perceive the disease as an economic threat. Farmers sell positive cows from herds with a high disease incidence but they are recycled to other herds or “fed to the public”.

Mycobacterium avium paratuberculosis (MAP) would rise in control importance, he said, if it is perceived as a threat to public health. The organism has been detected in infant formula by PCR but not by culture. As the organism is spore forming it is able to survive pasteurisation and samples of cheese have been found to be positive for MAP.

In Japan there is an increase in Crohn’s disease and an increase in milk consumption but any links are still unproven. MAP is killed by thorough cooking, but with burgers sufficient heat may not reach the centre. The organism is resistant to chlorine. The question is whether infection leads to Crohn’s Disease or whether Crohn’s patients are susceptible to MAP.

Antibiotic studies are continuing and if treatment becomes available this may remove some of the human concerns. However, vets and farmers can deliver raw products of low risk by providing milk and meat from test negative herds. This approach would provide the economic incentive to have a JD negative herd, he said.

Viable strategy

Dr Sam Strain (Animal Health and Welfare NI) has responsibility for Johne’s disease control programmes across Ireland. The aim is to provide confidence to overseas and domestic buyers of cattle and products by operating a viable control strategy, not eradication.

A veterinary on-farm risk assessment and risk management programme (RAMP) is at the heart of the initiative with some costs being met by government, some by participating milk purchasers (€300 in total) and the rest by the farmer.

Nearly 1,800 herds have participated to date in having the risk assessment, following training for 393 vets – one practitioner at least in every cattle practice. The aim is for every herd to be within 25km of a trained vet.

The training includes interpretation of diagnostic tests and tailoring advice to meet the requirements of individual herds. A scoring risk programme enables herds to be categorised from low to high risk.

Some farmers with herds that have confirmed negative test results join the scheme hoping to benefit from a low categorisation.

The work has already revealed some concerns. A quarter of herds feed insufficient colostrum and mix colostrum from JD (+) and (-) cows. Half the herds feed milk from the whole herd to calves, with a similar number feeding non-saleable (antibiotic) milk.

Half of the herds have no barrier between adult faeces and calves and on some farms the calving area also accommodates sick cows. Many herds leave calves on the dam for more than 30 minutes. The conclusion is that some on-farm practices increase the risk of having Johne’s disease within the herd.

Test challenge

Karen Bond (NMR) described the 30-cow ELISA test challenge where the cost of testing is refunded if the results are negative. The cows are selected from milk recording data or by veterinary selection, with the tests carried out on milk samples already being collected.

Initial indications from surveys are that few herds are clear of JD, some herds are making progress with the disease and others not. Despite receiving quarterly results, only half of the farmers are working with their vet to control the disease.

One positive ELISA test classifies a cow as amber and two positives as red. The majority of the farmers retain heifer calves born to red cows and some farmers do not consider amber cows to be a risk. Karen emphasised that correct interpretation of the current tests enables farmers to manage the risk of the disease.

Charles Harrison (dairy farmer) gave an overview of JD control in various countries that he visited as a Nuffield Scholar, following clinical disease within his own cattle. He emphasised that promotion of control strategies to farmers is recognised as difficult worldwide.

The view that “give a farmer a problem and he finds a solution but give him a solution and he finds a problem” applies particularly to JD. Keeping adult faeces away from calf mouths is an underlying management issue.

Management issue

Dick Sibley (Devon) pointed out that the ELISA test detects infectious animals but as the disease develops over years the test results are a reflection of historic management. A risk assessment indicates what is likely to happen in the future.

Herds may be clear of infection but their management indicates that the herd is at high risk for entry and spread of the disease. Surveys indicate that 80% of dairy herds and 32% of beef are within the high-risk category.

Ending on a positive note, Mr Sibley emphasised that anyone can manage Johne’s disease with a farm-specific biosecurity plan which includes only buying lower risk cattle than the herd status; the farmer doesn’t necessarily have to search for green category stock.

Peter Orpin (Leicester) considers it important that the farmer agrees that the control tasks will work for his specific herd. The elements of biosecurity, bio-containment and testing need to be reviewed regularly because a control delivery that is 80% applied will provide 100% failure.

Blocking MAP-infected faeces being transmitted to the calf is essential. Protection for low prevalence herds with no history of JD has to be an important part of the national initiative as well as reducing the incidence in high prevalence herds. The disease leads to unseen production losses and degrades farm profits and the message is, “Don’t just test and cull, don’t just test and hope, have a robust control plan.”

Information will be available shortly from a study by James Hanks, on behalf of NMR, to tease out the production and performance issues related to Johne’s disease. The performance of herds with high (over 14%) and low (less than 14%) proportions of positive cows are compared against each other and against the annual University of Reading 500 herd benchmark group.

Measuring progress

An advance analysis from James emphasises that at this stage the cause and effect aspects have not been clarified so the findings are preliminary observations only.

There are differences between low and high that can be measured and this will allow progress to be monitored. Veterinary practices will be able to measure progress across their whole client base and not just assess engaged herds. The chart is an example of the herd cell count data showing that a greater proportion of the JD high prevalence herds are at the higher end of the cell count range. Similar analysis indicates that these herds have lower lactation yields and fewer cows are served within 80 days of calving.

The whole spectrum of key performance indicators will be viewed against herd targets. Over time, as more herd and cow data for JD prevalence become available, it will be increasingly feasible to support farmers with hard data on progress and accurate risk assessment.

The national plan is to educate and involve farmers during 2015 and 2016 and put strategies in place specifically targeted to benefit the farm business. The organisers of this conference report that there has been a positive feedback from farmers to date.