Subsidised screening service shows worrying results

Recent data from DairyCheck and BeefCheck (Intervet's subsidised bulk milk and blood testing service) shows yet another rise in the number of herds testing positive for BVD and IBR.

Some 90% of tested dairy herds have been exposed to BVD and 70% to IBR. Of the beef animals tested, 38% have recently been exposed to BVD infection and 33% have come into contact with IBR in the past (see data at end).

Although these figures represent just a snapshot of what's happening in the national beef and dairy herds, they indicate both diseases are so common that many herds are unwittingly experiencing a drain on production and profits. Regular testing is therefore vital says Intervet's large animal veterinary adviser Rosemary Booth. "Internationally presented work shows that subclinical BVD causes the same losses as mastitis in a dairy herd, while IBR leads to higher culling rates and cattle failing to achieve expected weight gains. In dairy and suckler herds, puberty and age at first calving are delayed in replacement heifers," she says.

"If producers have stock showing signs of either BVD or IBR they should definitely test. But even in the absence of clinical signs, regular testing will give a benchmark from which to detect health problems should they arise. Monitoring is a good idea, even if you think that your herd doesn't have a problem.

"It's simple to test a bulk milk sample or blood test selected cattle. Under the DairyCheck and BeefCheck schemes sponsored by Intervet the testing is free, so what do you have to lose? The results give you and your vet a starting point to either monitor the situation (should the herd test negative, you want it to stay that way) or start investigating a problem."

Further tests can confirm whether any virus is still circulating in the herd. Both viruses create 'carrier' animals which continue to shed virus throughout their life, infecting their herdmates. Regular testing identifies these culprits so they can be culled from the herd, and all new stock vaccinated using Bovilis® BVD or Bovilis® IBR, Rosemary Booth says.

"Vaccination reduces the severity of disease and prevents the creation of new PI (persistently infected) calves, or IBR carriers, but should be part of a programme drawn up by a vet. This is likely to involve testing for (and culling) carriers, as well as regularly monitoring the herd to prevent re-infection, and giving annual boosters."

BEEFCHECK RESULTS

January to November 2007

Total no. herds tested BVD = 225

Total no. animals tested BVD = 1349

BVD positive titre >2 = 60.1%

BVD positive titre > 50 = 37.6%

Total no. herds tested for IBR = 170

Total no. animals tested IBR = 1016

IBR positive titre >2 = 32.7%

IBR positive titre > 50 = 12.2%

DAIRYCHECK RESULTS

January to November 2007

Total no. herds tested BVD 543

Positive = 89.7%

BVD positive titre > 2 = 23%

BVD positive titre > 50 = 66.7%

Total no. herds tested IBR 632

Positive = 70%

IBR positive titre > 2 = 36.4%

IBR positive titre > 50 = 34%