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Saturday 10 December 2016

Take steps to keep your herd free from Johne's

Beef

Published 12/07/2011 | 05:00

Johne's Disease is a slow, debilitating disease that we are seeing more frequently in herds nowadays. In years gone by, the incidence of the disease was so low as to call it rare in this country. There were only two herds in this practice area that were known to have the disease.

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More recently, we've seen more and more cases and now it's a disease we must all check for as part of the health status of our herds.

Johne's Disease spreads from dam to off-spring, particularly around calving time. The most obvious transfer of the disease occurs via the colostrum or first milk. The bacterium is present in the colostrum of the infected cow and when the calf suckles its dam, the bacterium enters the stomach of the calf.

In the first few hours after birth, the calf's intestinal wall can allow much larger proteins than normal to cross directly into the bloodstream. The bacterium is thus carried directly across into the calf's blood and the animal becomes infected for life. Therefore, the obvious way to break the cycle of disease is to avoid the consumption of infected colostrum.

To do this we must first blood or faecal test the cows and identify the carriers. Those cows then must have their colostrums discarded and their calves fed un-infected colostrums from a known disease-free cow. That sounds easy on paper but there are many complications with the steps just mentioned. We may discuss them another time.

eradicate

For today's report, suffice to say that all well managed suckler farms would be well wise to set plans in motion to eradicate the disease from their herd. Discuss the hows and whys with your vet and take solace in the knowledge that Animal Health Ireland is putting a big effort into helping farmers to identify and control this disease.

The disease itself, as mentioned earlier, is a slow-growing disease that can take up to four years or more to show clinical signs. The most obvious signs include a profuse diarrhoea and chronic wasting away of adult cattle. Treatment is impossibly expensive and simply not an option.

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Therefore, identification of the infected cows becomes paramount, and good veterinary advice on how to slowly turn your herd into a "Gold Star Johne's-free farm" must follow. A small look back in time might be useful here.

As mentioned earlier, Ireland was just about Johne's-free in the 1970s. Then Europe did away with the quarantine laws and livestock could move more easily from continental farms directly on to Irish farms. Professional advice at the time was that we should protect our island status and continue some form of voluntary quarantine when it came to cattle and sheep importation.

But price dictates, and we imported many beef and dairy breeding stock, a lot of which were already infected with Johne's Disease. Pooling colostrum and feeding one cow's milk to many newborn calves was common practice on Irish farms at the time.

There had been no problem with that practice up until then, but nowadays that must never be encouraged. However, many years have passed since those first continental heifers hit our farmyards and Johne's Disease is now well established in the national herd.

As beef suckler farmers we must stringently avoid the feeding of frozen colostrum taken from a neighbouring dairy farm that may or may not be infected with Johne's. Ensure your own herd is free of the disease and keep bio-security measures in place to stop the disease coming onto the farm. That means trying to source any bought-in heifers from disease-free herds and never use colostrum from another herd of unknown disease status. It is possible to learn from our collective mistakes and put solid boundaries of disease prevention around our farms.

If, when sourcing a replacement heifer, you cannot establish the disease status of the seller's farm, then quarantine the new heifer on your own farm. Don't let her mix with the herd until at least one test has been completed indicating a negative result.

This is not fool-proof because sometimes a heifer will not prove positive until over four years of age. Therefore, if possible, try and source from herds that have already tested all their cows and that all those tests came back with a negative result. That gives some comfort that the two- year-old heifers off that farm should be Johne's-free. It's a pity we didn't do that in the eighties. Animal Health Ireland will link all the individual disease-free herds in order to aim at achieving a completely Johne's-free national herd. Let's do it! Is féidir linn!

Peadar Ó Scanaill is a Meath-based vet and member of Veterinary Ireland's Animal Health Committee. Email: HQ@vetireland.ie

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