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Johne's Disease

You don’t have to see clinical cases of Johne’s for it to be present on farm. Take a look at our range of surveillance options to suit your herd’s Johne’s status.
What is Johne's?
Johne’s disease is a bacterial disease caused by the organism Mycobacterium Avium subspecies paratuberculosis (MAP). Infection results in a thickening of the intestinal wall. This prevents the animal from successfully absorbing nutrients causing the animals to lose weight and scour.
Johne's Cow
The disease causes considerable production losses within both dairy and beef herds worldwide. The classic clinical signs of scour and weight loss are well recognised. However, often the disease can exist unnoticed within a herd where culling rates are high as animals may be culled for repeated high Somatic Cell Count (SCC), repeat mastitis, poor yields, infertility or lameness long before clinical signs are evident.

Read our Intro to Johne's pdf under the Additional Information menu on the right for more information.
How is Johne’s spread?
The main route of infection is via faeces from infected animals contaminating the calving accommodation and pastures. However, transmission is also possible via milk, colostrum and intra uterine. Animals are at their most susceptible in their first 6 months of life, with the first month contributing to the highest risk of infection, in fact we believe most dairy calves are infected in the first 24 hours of life when they are with their dam. Johne’s management therefore includes identifying cattle that are infected, ensuring these cows do not calve in the main calving yard and their milk and colostrum is not used to feed replacement heifer calves. MAP can exist within the soil for over a year and thus care should be taken when spreading slurry on pastures which may be used to graze youngstock.
Establishing the status of the herd
A targeted 30-cow screen is recommended as a start point to assess status. The screen must be targeted at the animals most likely to be affected by the disease. NMR can automatically select 30 cows based on the last 6 herd recordings for an NMR herd. A study by the University of Reading found that lactation number (between 3 and 6) and SCC were the parameters with the highest association with positive Johne’s status. This automatic selection is available both as an ad hoc screen or as part of the HerdTracker service (automatic selection of 30 cows quarterly).

Bulk milk antibody ELISA testing is not recommended as a suitable tool for indicating prevalence of Johne’s within a herd. A low result is misleading. A bulk milk result can be low even if 9-12% of the animals contributing to the tank are testing ‘high’ for the disease (NMR analysis, unpublished results).

Read our Testing for Johne's pdf under the Additonal Information menu above right for further information.

NMR surveillance services:
  1. NMR HerdWise
  2. NMR HerdTracker
  3. One-Off Testing