* How will buyers know a calf has passed the test?
>>Livestock mart display boards will present BVD test details of all cattle tested under the compulsory programme.
This facility is already in place in many marts for this year’s results.
* What is the test procedure?
>>The compulsory programme requires all 2013 calves to be tested, using tissue sample-enabled official tags as part of the official tagging process.
The aim is to ensure persistently infected animals will not be sold in the marketplace.
Additional testing will be required where an animal is suspected of being infected with BVD virus.
Most commonly, this will involve the testing of the mother of a virus positive calf, but may also include other offspring of the mother if she tests positive.
The legislation includes the option to carry out a further test to confirm that the animal is persistently infected rather than transiently infected.
At least three weeks must be allowed between collection of the first and second samples, which may be taken using either a further tissue sample collected using a supplementary (button) tag, or a blood sample collected by a vet.
* How did voluntary testing go last year?
>>In the voluntary testing programme in 2012, 0.61% of calves tested positive for BVD.
Up to Jul 15, 392,858 calves born in 2012 were tested, in 8,770 herds — 13.6 % of the 64,367 breeding herds on the ICBF database.
This represented participation by 28.7% of dairy herds, 8.9% of beef herds, and12.5% of dual purpose herds.
Participation rates were typically higher in the south and east.
Overall, 0.61%, 0.02%, 0.44% and 98.93% of calves tested gave positive, inconclusive, empty (no tissue present), and negative results, respectively.
In total, 15.2% of the 8,770 herds had one or more calves with an initial positive or inconclusive result. Respectively, 18.1%, 11.6% and 20.6% of dairy, beef and dual purpose herds had one or more positive or inconclusive result.
Confirmatory testing of 1,013 calves with an initial positive or inconclusive result was carried out. Overall, 79.1% gave a further positive result, consistent with their being persistently infected with BVD virus. The other 21% gave a negative result on re-test, consistent with their having been transiently infected when the initial (positive) sample was collected. This typically occurs due to infection following contact with a PI animal before the tissue sample has been taken.
Tagging as soon as possible after birth minimises the chances of this occurring.
In follow-up testing of dams, 10% of dams of calves that were confirmed as persistently infected (PI) also tested positive for BVD virus, strongly suggesting that they in turn were PI. The balance tested negative, consistent with these heifers and cows having given birth to a PI calf following transient infection during pregnancy.
* What happened to calves that failed the test?
>>At the Jul 15 end of the review period, of the calves with an initial positive or inconclusive result, 67.7% were dead, and 29.4% were still alive in their birth herds. As expected, the retention rate of these calves was slightly higher in beef herds than in dairy herds.
Only 38 (2.9%) calves (from 28 different herds) with an initial positive or inconclusive result were present in non-birth herds — indicating that they had been sold.
* What did farmers think of the voluntary testing?
>>Results of a questionnaire indicated that most of the farmers who participated in the voluntary programme were satisfied or very satisfied with it, and found the guidelines easy to comply with.
Meanwhile, development of a programme in Northern Ireland being led by a recently-founded organisation called Animal Health and Welfare NI, in close collaboration with Animal Health Ireland offers the possibility of all-island eradication of BVD in the foreseeable future.