If there was ever a spring in her dairying career Trish Rankin would rather forget, it was back in 2013. While nine years ago, the award-winning dairy woman says the memories remain very sharp of a time when her and husband Glen had to deal with a Bovine Viral Diarrhoea (BVD) outbreak in their Wairarapa herd.
BVD is a difficult to diagnose animal disease that can have a debilitating impact on dairy herd production yet is often not fully understood by New Zealand farmers. Estimates are the disease is costing farmers and the industry about $150 million a year in lost performance or sick or dead stock resulting from it.
As a disease it can lurk quietly in herds, causing immune-suppression issues, wasting conditions and production losses, going undiagnosed for years.
Introducing Persistently Infected (PI) animals into a herd can result in it spreading fast. If a cow contracts BVD in her first four months of pregnancy while the calf’s immune system is also developing, the calf can be born as a PI animal. They will then spread it through the herd once they enter as milkers
The Rankins had to endure a harrowing spring before fully diagnosing the disease that delivered them 50-60 deformed or dead calves, and a further 30 calves that had to be euthanised once it was determined they too were carrying the disease, despite being outwardly healthy.
“We had been quite confident about disease risk because while ours was one of three herds, there were no new cows coming in. However, a PI bull came in for mating, he did not look too good, but we did not think too much about it at the time.”
It was not until calving it became apparent just how unwell the bull was.
“Once the calves started being born the vets were looking at salmonella, rotavirus.
“But it was not until I did a Google search on BVD that we found what it was. We did a blood test on the replacements and 30% of the ones that looked so healthy also had it and had to be put down.”
The couple had to grapple with sick calves through calving, putting IV drips on the worst and tubing them to feed them, being too weak to drink properly
Once they had determined it was BVD, they also realised they had been unintentionally spreading BVD among the calves by putting infected ones with healthy ones.
A bulk milk sample of the herd revealed “ridiculously high” levels of BVD infection with almost all the milkers suffering a level of illness.
The couple’s next contract milking job in Hawke’s Bay had them taking extra care over introduced animals, avoiding using bulls and sticking with AI while also ensuring the owner had the herd vaccinated for BVD.
Today they are farming in Northland, and the lessons from that terrible spring resonate even further, now they own their own farm and herd.
“We vaccinate for BVD and keep bought out bulls out of the herd. Vaccination is not necessarily the cheapest thing to do, but it gives you control over a very complex disease and stops you having to experience the ‘ambulance at the bottom of the cliff’ experience we had.”
Trish says she is still surprised by the relative lack of active management among farmers to deal with BVD before it becomes a problem, but acknowledges it is a disease one does not fully appreciate until it has been experienced first-hand.
“With vaccination BVD is not an issue for us anymore, and the next disease we want to focus on is Johne’s, also a tough one to identify.”
