The newly developed test is a spin-off from research by the University of Otago’s Disease Research Laboratory (DRL) and an extension of tests it designed to identify TB and JD in deer.
The development was led by Frank Griffin, Rory O’Brien and Simon Liggett after dairy farmers and veterinarians pooled their resources to work directly with the DRL team – mirroring the approach deer farmers took when they tackled JD head-on.
Johne’s disease was believed to be draining at least $100 million from the cattle, sheep and deer sectors through production losses, reduced fertility and animal deaths.
Griffin said several of the dairy farmers involved in the onfarm studies suffered annual capital losses directly attributable to JD of $100,000-plus.
Direct costs included culling infected cows before the end of their productive lives, reduced milksolids production, poor reproductive performance and increased susceptibility to other diseases.
Vetlife Temuka veterinarian Andrew Bates, one of those who persuaded Griffin to do the work, said infection levels in some herds in his patch were such that the number of cows being culled ran into double digits each season.
Until now dairy farmers unlucky enough to experience ongoing production losses because of clinical disease had few control options.
“Control has been traditionally challenging, diagnosis is straightforward once the clinical signs show.”
But by that time it was too late because the damage had been done, Bates said.
While JD might present as clinical disease or result in significant productivity losses in only a small proportion of herds, evidence suggested about 600 New Zealand dairy farms could benefit from JD management plans.
Griffin’s team began working with several JD problem dairy herds in 2006 showing the wasting disease could be controlled relatively quickly and cost-effectively in one to two years.
However, rejection by industry advisers of any real relevance of JD to NZ dairying meant gaining funding was difficult so the DRL team funded the research themselves.
Recognising the client benefits, veterinarians involved provided their services to the dairy farmers at reduced rates and DRL its diagnostic services below cost.
Onfarm studies began in 2008 in collaboration with Vetlife, involving two South Island herds totalling 2400 cows.
The breakthrough came in 2010 when the DRL team applied two unique tests in combination to dairy cows, the first an immunological test (ELISA), the other a microbiological test (qPCR). Each test targeted a different aspect of JD diagnosis.
Since then more than 10,000 cows, 5000 sampled in detail from four herds, the rest spread over 30-40 herds, were involved in validating the technologies. That included matching blood serums and faecal samples of individual cows.
The outcome was maximum disease control and salvage, lesser financial costs involved with culling and greatly reducing the ongoing JD spread in the herds, especially from cows to their offspring at calving.
A 2014 AGMARDT grant enabled the researchers to acquire necessary hardware to translate the technology from an expensive, low-throughput research tool into a practical and usable, frontline, in-herd, diagnostic test for everyday use.
The result was a high-tech and high-throughput yet practical and inexpensive diagnostic tool with real commercial applicability, Griffin said.
The tests had subsequently gained international validation through United States Department of Agriculture testing and accreditation.
