Livestock Matters - Summer 2018

BVD CASE STUDY WORKING TOGETHER FOR A HEALTHIER FUTURE... 1 7 LIVESTOCK MATTERS Dynamics of BVD disease require a strategic approach for control Worcestershire farmer Richard Coleman knew about BVD and always sourced bulls for his suckler herd from High Health status farms. But he had never tested his own herd for it. Richard farms with his wife Sarah, and son Henry at Sponend Farm, near Ledbury. The 40 cow Simmental-cross suckler herd is not the main enterprise and priority has always been given to the laying hen unit and sheep flock. Richard admits: “The cattle always came third in the pecking order and we had slipped into bad habits. Cow fertility had decreased and led to protracted calving blocks - in spring and autumn.” When their farm vet retired at the end of 2016, the Colemans moved over to using the services of Belmont Vets, and began to receive a proactive approach from vet Matt Pugh. Heifer screening One of Matt’s first recommendations when discussing the herd’s fertility was to blood-test the yearling animals for BVD. Matt explains: “Testing this group will show what the health status of the whole herd is like. Tests were carried out on 10 of the 15 heifers, and one animal showed a high antibody titre to BVD. We waited three weeks and then re- tested the whole group. “Heifers that had previously been antibody negative were now antibody positive, indicating they had recently been challenged by the BVD virus. This is known as transient infection. It can occur through contact with an animal shedding the virus e.g. a neighbour’s cattle over the fence, or a slip in bio-security that leads to the virus being carried onto farm inadvertently e.g. on mucky wellies/kit from another farm, cows returning from shows where they have encountered a PI.” Richard says: “When Matt explained how PI animals can give rise to secondary infections – it struck a chord. In recent years we have had problems with scouring calves. They are fine for the first few days after birth, but then scour and it is more challenging to cure them. We had been wondering if it was a problem with the shed.” Matt gave the Colemans two options to track down the culprit PI animals: Tag and Test all cattle, or blood test all cattle. “Belmont priced it all up for us, and we decided to go with the blood-testing,” explains Richard. “The results were all clear! No PIs in the herd! But then Matt pointed out that some cows were in-calf so we couldn’t know if the calf would also be clear or not.” “So in the spring of 2017, we Tag and Tested all the newborn calves. Unfortunately, one of them turned out to be a PI. That was painful! It was the best looking calf! Nevertheless it was culled.” Richard adds: “We sell our weaned calves as stores at eight months - so we’d have been spreading BVD onto other farms without knowing.” Vaccination with monitoring Matt explains: “Richard’s farm neighbours onto other farms with cattle. It’s not feasible to make all the field boundaries stock-proof. So vaccination is needed as an insurance against these ‘leaky boundaries’.” All cows and heifers due to be mated in the coming 12 month period are vaccinated, plus the bull. The Tag and Testing of calves will also continue as a way of monitoring the situation. The benefit of this has been demonstrated after some pregnant cows came into contact with some other cattle, later resulting in the births of four PI calves. Matt adds: “As a further check, we will also blood test a sample of animals annually. This will be done at the same time as a TB test, when a vet is already on-farm.” Farmer Richard Coleman An in-calf heifer may test clear of BVD but she might still be carrying a PI calf. All calves are now Tag and Tested at birth to check there are no new PIs coming into the herd.