June 2026 – Preventing Johne’s in Your Herd

One of the issues with Johne’s which makes its control difficult is that once animals become infected the disease progresses slowly and silently. Very commonly, signs of Johne’s disease won’t become visible until an animal has had three or more calves and infection has at that point become established in the herd. All of this means that the key to avoiding the introduction of many diseases onto your farm, including Johne’s diesease, is to always practice effective biosecurity measures; and when unsure take advice from your veterinary practitioner who has in depth knowledge of this subject area.

1. Movement of infected animals into the herd
   Remember that animals infected with Johne’s disease may appear healthy and may even have had a negative blood test for Johne’s. However, these animals have the potential, even when they appear healthy, to be releasing large numbers of bacteria in their faeces into the farm environment, potentially beginning the process of infecting other stock on the farm, especially younger animals.
2. Infected Colostrum
   Colostrum can be a risk when it is harvested using inadequate hygiene or when it’s collected from infected cows.
3. Slurry/manure (other than pigs or poultry)
   This contaminated slurry/manure imported onto your farm risks contaminating your own pastures with the bacteria that causes Johne’s disease. Younger stock will be especially vulnerable to this infection route.
4. Returning Animals
   Animals that have left the home farm for variable lengths of time can be exposed to infection by grazing contaminated pastures or through contact with infected dung in off-farm heifer rearing units, or at shows and marts.
5. People
   Workers/visitors coming onto your farm can spread infected dung on vehicles, equipment, boots and overalls as they move between herds. Pay particular attention to vulnerable cohorts of animals, namely calves and young stock.
6. Vehicles
   Trailers and farm machinery can introduce Johne’s contaminated dung to a farm and spread it throughout the farm as equipment is moved around.

Buy wisely
Reduce the number of herds and number of animals used to source introductions into your herd. If you are purchasing animals ideally source these from low-risk source herds. Low risk sources are closed herds or those which can demonstrate several years of negative Whole Herd Tests.

Avoid bringing in colostrum
In terms of bringing colostrum from outside sources onto your farm, this should be completely avoided unless from a high assurance source.

Be cautious with slurry and manure
With slurry/manure it is best not to import this at all. If you do import slurry/manure avoid its use where young stock are grazed and if contractors come onto the farm, make sure vehicles are thoroughly cleaned before they gain access.

Check biosecurity at off-farm units
When moving stock to off-farm locations, avoid pastures where slurry has recently been spread. Check biosecurity practices of contract rearing units before sending calves/young stock.

Manage visitors carefully
In terms of workers coming onto the farm restrict access especially to calf areas, making sure anyone on farm is wearing clean clothing, disinfected before entry. If necessary, provide clean washable overalls and wellington boots to workers accessing your farm. Also make sure you have accessible cleaning facilities making it easy for workers to clean/disinfect boots and overalls. Signage may also be of use to provide information about staying away from restricted areas.

Clean vehicles and equipment
Ensure vehicles, trailers and machinery have clean external surfaces and internal surfaces have been washed before entering the farm. Remember machinery such as slurry/manure spreaders and dirty livestock trailers are of a particular high risk and should not enter the farm in a dirty state.

Control farm access
Minimise numbers of visitors and number of entry points to the farm. Establish barriers (e.g. gate) with biosecurity notice and disinfection points and foot baths at the main entry points to the farm. Maintain restricted access for visitors to vulnerable livestock such as calves.

Prevention is better than cure
Because Johne’s disease develops slowly and has no cure, prevention is your best investment. Strong biosecurity, careful purchasing decisions and protecting young animals from exposure can significantly reduce the risk of introducing Johne’s disease to your herd. Every farm is different, so work with your veterinary practitioner to develop a practical biosecurity plan that suits your system and helps safeguard the long-term health and productivity of your herd.