Johne’s is a chronic, and irreversible disease of ruminants caused by Mycobacterium avium paratuberculosis (MAP).80% of infections occur within the first month of life. Infection is mainly caused by ingesting faeces from contaminated bedding, udders, teats, colostrum or milk. Much less commonly the infection can be acquired in the womb or later in life.
Johne’s infections are almost always introduced to a herd by purchasing infected replacement breeding stock. There are other risks of introducing the disease including importing slurry from other farms and swapping colostrum between herds.
Johne’s disease adversely affects the physical and economic performance of a dairy herd. Johne’s test positive cows are twice as likely to have a cell count >200,000 cells/ml and are twice as likely to have milk yields 25% below their herd average. Johne’s disease costs can rise to excess of 1-2p/litre with high disease incidences and these costs remain until the disease is brought under control.
With Johne’s the major cost comes from increased susceptibility to other conditions and increased culling rates. For every clinical case seen, there are approximately 20 other cows sub clinically affected. It is calculated that 2/3 of dairy farms have Johne’s disease present on the farm.
The National Johne’s Management Plan (NJMP) was developed to help manage and reduce incidence of Johne’s disease in dairy cattle. International experience has shown that if a rigorous control program is implemented and applied robustly Johne’s disease can be brought under control. Every dairy is required to have in place phase 2 of the NJMP. This plan seeks to manage and reduce the incidence of Johne’s disease on our farms through implementing one of the six strategies agreed by the NJMP group, and monitored on each farm by BCVA accredited vets.
There are several BCVA accredited vets in the practice for you to discuss your Johne’s strategy with.
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