Technology being used across New Zealand to detect covid in wastewater samples is being employed in the dairy sector to detect disease in herds.
LIC has created a new test using a farm’s effluent system to detect if a herd has Johne’s disease.
The test is a NZ-first for farmers, to help them detect the disease and prevent the spread of it on their farm, protecting the health and wellbeing of their animals.
Johne’s disease is caused by a bacterium, which infects the gut of dairy cows and other ruminant animals. Common side effects include lower milk production, difficulty reproducing and rapid weight loss. It is estimated to cost NZ more than $40 million in lost production a year.
The test uses the same technology used to detect covid-19 in wastewater and like that test, it was a surveillance measure, LIC chief scientist Richard Spelman says.
“We developed this test because Johne’s disease is common in dairy cows but it can be difficult to detect,” Spelman says
“Infected animals often don’t show physical symptoms of the disease, meanwhile their milk production can drop and they spread the infection to others.
“This new test provides famers with a cost-effective way to screen their herd for Johne’s disease and use this information to determine whether individual animal testing is required.”
The effluent test was another tool that farmers can add to their toolbox.
The test comprises four samples taken from different areas of the farm’s effluent system.
Similar to the covid test, where RNA is extracted from wastewater sites and analysed by Polymerase Chain Reaction (PCR), the LIC test extracts DNA from the effluent samples, which are analysed by scientists using the same type of PCR test.
Each effluent sample receives a detected or not detected result.
“If Johne’s disease bacteria is detected in a sample, we encourage farmers to get each of their cows tested using blood or herd test milk samples to identify carriers of the disease,” he says.
If there is no sign of the bacteria on-farm in the initial effluent test, LIC’s research shows the herd is likely to either be currently disease free, or low in disease prevalence.
Annual testing is recommended so farmers can identify if or when animals start shedding Johne’s bacteria into the effluent system.
Spelman says now is an optimal time for most farmers to consider using the effluent test.
“For spring calving farmers, it’s best to test from September to December to help ensure the entire herd is captured in the effluent samples,” he says.
