Johne’s Disease: Do you know risks?
As of winter 2020 a Johne’s risk assessment has now been added to the list of requirements for Red Tractor inspections because of the disease’s implications on farm production and profitability.
A clinical case of Johne’s can be easily recognised as the thin cow who keeps getting thinner, does not respond to treatment and scours continuously, but are we missing positive cases on well managed farms because the cows are culled for other reasons?
Research has shown that subclinical Johne’s positive animals (those not showing signs of disease):
- Have a 9-13% reduction in 305 day milk yield
- Are half as likely to conceive to first service
- Have a 35 day longer calving interval
- Have a cell count that is 36% higher and
- Are culled an average of 160d earlier than Johne’s negative cows.
It is therefore likely that in a well-managed herd, Johne’s cows are culled for all of the above reasons before they show clinical signs.
The Johne’s Risk Assessment & Management Plan (RAMP)
The point therefore of the risk assessment is to gain insight as to whether the herd is a high risk for having Johne’s present and whether the current management practices would accelerate the spread of the disease.
It is believed that up to 50% of herds in Northern Ireland could have Johne’s disease present, with the majority of farmers unaware of the positive cases. Few farms are lucky enough to be able to describe their herd as being “completely closed” due to boundaries with neighbouring farms, the purchase of stock or the use of contractors to spread slurry, so the risk of bringing Johne’s disease onto the farm is also high.
Although there may be some management factors that are difficult to change, the Johne’s RAMP is a fantastic way of increasing farmer awareness of potential high risk management decisions that aid in the spread of the disease – pooling colostrum and leaving calves in calving pens to name a couple. If a Johne’s positive cow’s milk is pooled and fed to a batch of heifer calves who are then kept for replacements, it is highly likely that all of the heifers will have been infected with Johne’s and will therefore be less profitable animals.
The management choices farmers make today could have a huge impact on the herd that they milk in 5-10 years time.
By taking the time to go through the Johne’s Risk Assessment with your vet, farmers should be able to identify where the bottle necks are for spreading disease and set up protocols to decrease the risk, hopefully improving the profitability of the herd for years to come.