Farm Ireland

Saturday 21 July 2018

Tackling threat from BVD must be an immediate farmer priority

John Shirley

'When we got rid of the BVD from our herd there was a transformation in overall herd health. Calves suffered much less from scour and pneumonia. Fertility in the cows dramatically improved. Our farming in the past year became a lot easier and less stressful without the dead hand of the BVD virus."

These sentiments were expressed by Jim and Grainne Dwyer, who keep a 200-cow dairy herd in Borris-in-Ossory, Co Laois.

Ironically, the Dwyers had been vaccinating against BVD all along, but like a lot of herds theirs had a couple of unidentified saboteurs that continued to shed massive amounts of virus. These saboteurs have become known as PIs -- persistent infectors.

PIs arise when an unborn calf picks up the infection before the fifth month of pregnancy. A PI animal can look perfectly normal but BVD-wise, it's a herd wrecker. Vaccination has no effect on PIs.

PIs were not identified by earlier antibody testing but they can be by a newer PCR test which detects the actual virus.

The Dwyers learned about the BVD (bovine virus diarrhoea) PIs from Teagasc Moorepark. Their herds, too, had struggled with BVD infection until the PIs were identified and eliminated. The Dwyers followed the Teagasc guide -- a bulk milk test on the cows plus a blood test on non-vaccinated calves and weanlings. If infection is found, the whole herd is screened for PIs. If any PIs are found, slaughter them the next day, if not sooner. In the following years, keep checking young stock for PIs. Also, continue to vaccinate -- despite the cost.

BVD is highly infectious and the country is riddled with it. Surveys show that between 80pc and 90pc of herds have been exposed to the disease. Because it weakens the animal's immune system it can be the causal factor behind scours, pneumonia, infertility, abortions, mastitis -- you name it. It's an abomination to have it in your herd. No wonder the Dwyers got such relief when it was banished.

BVD has been eliminated, or is in the process of being eliminated, across most of Northern Europe. For far too long Ireland muddled along with BVD while the infection continued to spread. Many local vets are only now getting au fait with the PI threat and how to handle BVD. After the debacles on TB and brucellosis, the Department of Agriculture ran a mile from another compulsory eradication programme. Suggestions that the brucellosis blood sample be also routinely tested for BVD, IBR and Johnes fell on deaf ears within the Department.

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However, awareness of the BVD threat has improved of late. Animal Health Ireland has made it a priority disease to tackle. Progressive Genetics and Munster AI include BVD in their disease testing service on milk samples and will give back-up advice. Co-op Animal Health are also offering a testing and back-up service.


Hopefully, pedigree cattle breed societies from here on will include freedom from BVD infection in the bulls and females at their shows and sales. The BVD virus (and IBR) can be carried in the bull semen into a BVD-free herd. Indeed, the lack of testing for BVD/IBR/Johnes at the pedigree sales does no credit to pedigree societies. Too many herdowners have brought infection into their herd with the purchase of a pedigree bull.

AI stations rigorously test for these diseases before a bull can be taken into the service. To give credit to the Beef Performance Test station at Tully, Co Kildare, they too rigorously test all their bulls for threats such as BVD, IBR and Johnes. Of late, thinking beef farmers have purchased stock bulls from Tully as much for their health status as their genetic ability.

BVD is not the only disease that needs higher awareness among dairy and suckler farmers. One can also argue a case for combating IBR, Leptospirosis, Neospora and maybe Johnes, but one can only tackle so much at a time. And the fact that BVD can undermine the animal's entire immune system makes it top priority. More farmers should tackle this threat and avail of the farming bonus that was experienced by the Dwyers.

Irish Independent