July 2026 – Protecting Youngstock from Johne’s Disease at Pasture

Johne’s disease is caused by a bacteria called MAP, which can be present in dung and slurry. MAP is a persistent bacteria and can survive on pasture for many months after the ground has been contaminated. Youngstock are particularly susceptible to infection, so taking steps to reduce their exposure is important.

Keep youngstock away from high-risk areas

Where possible, avoid grazing young calves on land that has:

• Had slurry or manure spread on it recently.
• Been heavily grazed by adult cattle.
• Been contaminated with dung from other livestock.

Ideally, calves would graze land that has not received slurry or manure and has not been grazed by adult cattle for the previous 12 months. While this may not be practical on every farm, farmers should consider how grazing can be managed to reduce the risk as much as possible.

Be particularly cautious when spreading slurry or manure brought in from another farm. If contractors are used, machinery and equipment should be properly cleaned before entering your farm to help prevent the spread of MAP and other infectious diseases.

Consider a leader-follower grazing system

A leader-follower grazing system can be a useful way of managing youngstock at pasture.

In this system, calves graze fresh paddocks first before being moved on, with older cattle such as yearlings following behind. The calves are therefore exposed to lower levels of parasites and potentially lower levels of MAP contamination, while the older cattle graze the remaining grass.

After a period of grazing, the calves can return to the paddock once it has had time to rest. Rotating between several paddocks and avoiding continuous grazing of youngstock in the same areas can further reduce the build-up of infection and parasites.

Where possible, use yearlings rather than adult cattle to follow calves. Yearlings are less likely to be shedding high levels of MAP, even if they are carrying the infection.

Make the most of lower-risk ground

Land that has been reseeded or used for silage in the previous season may provide a lower-risk grazing option for youngstock. Rotating young cattle through multiple fields can also allow more time between grazing periods.

However, grazing management needs to consider other risks too. Fields dedicated to youngstock may have a higher burden of gut worms and coccidia, so parasite control should be part of your overall grazing plan.

Sheep can also carry MAP, so co-grazing sheep and cattle should be avoided where possible, particularly on farms where Johne’s disease is known to be present.

Protecting youngstock starts with good grazing management

Young calves are the most vulnerable to MAP infection, so reducing their exposure to contaminated pasture, dung and slurry is an important part of Johne’s disease prevention.

Think about where your youngstock are grazing, what has happened on that ground in the previous year, and how you can rotate stock to reduce their exposure to infection.