Disease is a huge cost in reduced health and productivity and, for a Shropshire dairy farmer, this has meant a £50,000 loss in reduced milk production, increased cow treatments and mortality.
Over the last five years infectious bovine rhinotracheitis (IBR) has been our single biggest herd health issue, says Andrew Evans (pictured below) of Bubney Farm, Whitchurch, Shropshire.
“Historic IBR infection was costing the business thousands until a whole-herd vaccination regime finally allowed us to get on top of the problem.”
Andrew and his wife Janet took on her uncle’s farm in 2004 and have since built up the herd from 200 to 800 Holstein Friesians and Brown Swiss crosses averaging 8500 litres a cow a year.
“IBR first surfaced visibly in 2005 after we’d pushed the herd up to 350 cows,” says Mr Evans. “A number of third/fourth lactation cows were off colour with one or two showing clinical symptoms such as runny noses, milk drop and a high temperature.
“In the end, 60-70 cows were affected and we lost six animals and an awful lot of milk. This was the first time IBR was diagnosed and we immediately started vaccinating intra-nasally.”
Initially, booster vaccination was carried out annually and, although the situation did improve after initial vaccination, once cow numbers got up to about 500 the farm started to get IBR breakdowns.
“It was at this point we were advised to vaccinate every six months to minimise viral shedding and maximise control.”
According to Mr Pedley, IBR diagnosis is not always straightforward because its symptoms mirror those associated with other conditions.
“Farmers may see raised temperatures, milk drop, nasal discharge, a drop in intakes and even abortion, all of which are seen with other diseases, so IBR infection can often be missed.
“But once symptoms appear, an affected animal can shed large quantities of virus from the airways and nose, which means any uninfected cattle, such as herd replacements, for example, will always be vulnerable to infection,” he says.
IBR is a highly contagious disease of the upper respiratory tract and the most common way of bringing it into a herd is through bought-in cattle of unknown health status or via semen of infected bulls.
“Once animals are exposed to the virus they can remain carriers for life,” Mr Pedley says.
“Because IBR is a herpes virus – the same family of viruses that causes coldsores in humans – cows can’t always remove it from their bodies. “The virus then remains dormant until stress factors such as calving, stock movements or extreme weather trigger recurrence of clinical signs.”
And results from the Intervet/Schering-Plough Animal Health Beef and DairyCheck national diagnostic services show more than 70% of UK herds test positive for the disease.
“It is highly advisable herds are screened regularly for IBR, “he says. “You can test bulk milk and blood for antibodies to IBR, but one off tests may not be conclusive, and repeat tests may be necessary.
“A more rigorous approach is to ask your vet about paired serology, which involves taking blood samples 3-4 weeks apart. Often, response to vaccination is the simplest way to see if you have an IBR problem – when active virus is circulating, you will generally see improvements in herd health within 36 hours,” Mr Pedley says.
“I have seen situations where farms appear to have only one clinical case of IBR but, after vaccinating all cows, the farmer has had to put more feed out a couple of days later – invariably, IBR is grumbling away and keeping a lid on whole-herd performance.”
This is a scenario that resonates with Evans. “On our farm in Cheshire we definitely had the odd case and got by through treating individual animals. With the benefit of hindsight we were lucky it didn’t blow up into something more serious.
“Our experience at Bubney has shown us you can’t be complacent with this disease – it will make you pay in the end. We have now built twice-yearly IBR vaccination into our herd health plan,” he says.
• More from our disease check series here.