Tackling threat from BVD must be an immediate farmer priority
Published 23/02/2010 | 05:00
'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.