Johne's can be an elusive disease. Calves become infected with the Johne's bacterium MAP, typically at less than 6 months of age. The disease remains hidden for several years with animals not generally testing positive until they are at least 2 years of age.
Testing every cow at herd test time with a milk antibody test through LIC (cost approx. $5.50 per head) means you can identify infected cows before they lose weight and scour. These animals can therefore be sold for cull cow value. In many herds, the offset of cows sent for slaughter vs sent to pet foods covers the cost of testing.
Removing infected animals before they start shedding MAP bacteria in large numbers, in conjunction with developing a Johnes control plan with your vet is the best way to reduce the incidence of Jones in your herd over time.
LIC have also released a Johne's effluent PCR screen. If you are unsure of your herd's status, this could be a useful tool to confirm a positive Johnes status.
Now is a great time to start thinking about Johne’s control in your herd- pick up the phone and chat to your vet today!
Dr Jason Fayers BVM&S CertCHP (Cattle Health & Productivity)