Johne’s FAQs

It is common for calves to be infected in the days after birth, but as Johne’s progresses very slowly, it is uncommon to see clinical signs before cows are three years old.

Cows are likely to test positive before you start to see clinical signs.

There is no evidence that certain breeds are more likely to become infected, but some breeds seem to have different progressions of the disease than others.

For example, Holsteins have a lengthy period without clinical signs of weight loss and diarrhoea, though you may see impacts such as reduced milk yield or high cell count, and they may test positive one quarter, then negative the next and so on. This phase can often go on for years.

By contrast, Channel Island breeds seem to go from testing negative to returning a high positive test and increasing antibody levels in a short period of time and show a more rapid progression of clinical signs.

Breed of cow does not represent a significant barrier to controlling Johne’s disease on farm.

There is currently no evidence that larger herds have greater levels of infection than smaller herds.

There is a vaccine against Johne’s disease, but it has limited efficacy. This is because calves are usually infected in the first few days of life, so they are already infected by the time they get vaccinated.

The vaccine does not prevent infection, and it cannot stop an infected cow from shedding the bacteria in her faeces and infecting others in the herd. However, it does extend the time before an infected cow shows clinical signs, so she has a longer productive life.

Vaccination should not be used as the sole control method. You should only vaccinate if you have a clear exit strategy and understand the implications of vaccinating.

Once a herd is vaccinated, it is difficult to tell whether an animal is infected because the tests cannot tell the difference between antibodies from infection and antibodies from a vaccine.

1. Start by discussing your current situation with your BCVA-accredited Johne’s veterinary adviser (BAJVA). The vet–farmer relationship is essential to Johne’s control, and every farm is different, so your plan should be bespoke to your situation and your needs.
2. Take a look at your data with your vet. Which quartile is your herd in? Are you making progress, and if not, why might that be?
3. Agree some areas of focus for the next year with your vet. The data is a tool to help you understand what management changes would be of benefit. Risk assessments, sticking to plans and involving the whole farm team are key to success.

Phase I ran from 2015 to 2017, focusing on education and engagement surrounding the disease.

Phase II ran from 2018 to 2025 and required farmers to implement one of six control strategies.

Vets received training to become accredited Johne’s advisers.

Johne’s management was incorporated into Red Tractor standards for farmers and processors.

The Johne’s Tracker Database was developed to give farm history of disease.

Both phases made excellent progress in beginning to control and reduce the incidence of Johne’s disease.

Key changes for Phase III include:

• All herds must obtain an average test value (ATV) for their herd to help assess disease levels and allow progress to be tracked over time
• The minimum requirement to generate an ATV will be a 60-cow random screen. The 30-cow targeted screen is no longer an acceptable option
• The creation of a national Johne’s Control Index, with a goal to achieve a target 5.5 ATV by 2030
• The ability, through the creation of a national Johne’s Tracker Database, to track progress nationally using ATV, % incidence and other drivers of infection within herds

To control and then reduce the incidence of Johne’s disease in dairy cattle, with the aim of achieving a national mean ATV of less than 5.5 by 2030.

The use of ATVs enables farms to track their own progress over time and to benchmark themselves against the Johne’s Control Index.

Until recently, there was no method of quantifying progress by prevalence within herds.

Since the development of the Johne’s Tracker and Tracker Database, we can track progress at a national level as well as at a herd level.

As a result of dairy farmer investment and commitment, the industry has made excellent progress over the last few years, meaning that previous benchmarks are now outdated.

The benchmarks have been updated to reflect this progress, and the NJMP now requires that all farms obtain an ATV to be able to track their own progress against time and to benchmark themselves against a national aspirational standard (Johne’s Control Index).

Yes, having an NJMP in place on your farm is a Red Tractor requirement for dairy for both farmers and processors.

The ATV is the mathematical average of all the Johne’s tests carried out at a single point in time.

It is a continuous variable rather than a binary result, and it can be used as a simple assessment of Johne’s load within a herd. 

The ATV is a useful metric because it moves the focus away from thinking of Johne’s tests as positive/negative.

The nature of Johne’s disease means that an infected cow may not always test positive.

Using ATVs rather than counting the number of positives accounts for all cows in the herd, including those that are low test positives and inconclusive.  

The Johne’s Control Index (JCI) is a fixed target that individual farmers and the industry can aim for. It has been set at an ATV of 5.5, which we want to achieve nationally by 2030.

Herds that consistently achieve an ATV below 5.5 have the disease well controlled.

Their new infection rate is normally low, priority culls are largely absent and the disease is more of a minor nuisance than a big problem.

We want to pursue acceptable control as eradication is extremely difficult.

The national ATV at the end of 2024 was 6.71. At the moment, about 41% of herds in Great Britain are already achieving the JCI of 5.5.

Three out of four herds have reduced their ATV since 2020.

No, if you’re already doing whole-herd testing, then you do not need to do a 60-cow random screen in addition to this.

The 60-cow screen is a minimum testing requirement and represents testing for surveillance.

It can generate an estimated ATV to give you a reasonable idea of the level of disease in your herd and give you the ability to see whether you are making progress.

However, the 60-cow screen cannot give you individual information for all of your cows.

A whole-herd test represents testing for control because it gives you information about every cow in your herd.

You can then make informed management, breeding and culling decisions based on individual Johne’s status.

The 30-cow screen was a targeted screen, where cows likely to be infected were deliberately chosen to hunt the disease out on farm.

The objective of the 60-cow screen is to provide a low-cost method to estimate herd ATV. It is an appropriate level of surveillance for flying herds.

To work properly, the cows must be selected randomly.

Yes, there are new training module for BCVA-accredited Johne’s veterinary advisers (BAJVAs) to undertake before they can fill out the new declaration forms.

Check with your vet whether they have completed these modules before your next annual review.

You can find your nearest BAJVA through the Action Johne’s website: BCVA-Accredited Johne's Veterinary Advisers – The National Action Group on Johne's

Yes. You now have to include an ATV for last year (if available – if you did a 30-cow screen last year, you will not have an ATV) and for this year.

There is also space to include three SMART priorities (specific, measurable, achievable, relevant and time-bound).

These targets should be agreed between farmer and vet and are there to give accountability and focus areas for the year.

The declaration provides an opportunity to review progress and celebrate success and also to optimise your plan and make sure you are on track to achieve your targets.

Some examples of high-level SMART targets that could be adapted to your needs are:

• Detailed risk assessment of all potential areas where Johne’s disease could be spreading within the herd
• Further training for all the farm staff on Johne’s control
• Specific areas of the control plan that need attention or focus, e.g. identifying high-risk cows, segregation
• Change of strategy
• Deciding on frequency of vet review of data, farm risks or management plan
• Refining criteria for culling based on resources and heifer numbers
• Breeding and risk management in new areas, e.g. reducing risk of transmission from dam to calf or calf to calf
• Prioritising certain areas of the plan over the year, e.g. breeding, identifying high-risk animals, blocking calf-to-calf transmission

This list is not exhaustive and you should discuss your SMART priorities with your vet.

The declaration forms can be found on the Action Johne’s website here: The declaration - The National Action Group on Johne's

The industry has made enormous progress over the last few years. This means that the benchmark values are now out of date.

In essence, we have been using data from 2020 to benchmark herds in 2024.

Using the 2020 data, 75% of herds appear to be in the top-performing 25% of testing herds.

Action Johne’s is now using more recent data to set the boundaries.

These boundaries will now use rolling yearly data, rather than three-yearly, so changes are gradual rather than a big jump. 

This means that the colours in your report might have changed, but it is important to note that the numbers have not changed.