University of Sydney PhD student Jia Ling Vivien Tan analyses kikuyu DNA samples as part of the DairyUP kikuyu toxicity project.
NSW DairyUP researchers want to hear from any farmers who suspect their cattle might be suffering from kikuyu toxicity, as scientists seek answers to a problem that’s plagued farmers for decades.
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Autumn is the prime time for cattle to show the effects of kikuyu toxicity, especially in regions that have gone through a dry summer and receive an early season break.
This means it’s also the best period for researchers to collect samples of “toxic” kikuyu to solve a problem that causes cattle deaths and illness.
NSW Department of Primary Industries Plant Pathology Research leader Krista Plett said understanding the cause of kikuyu toxicity would provide evidence-backed information to dairy farmers to make grazing and planting decisions and minimise kikuyu-related cattle deaths.
“Kikuyu poisoning is rare — which we are thankful for — but this makes it difficult to research,” she said.
“The compound or mechanism that makes kikuyu toxic to livestock and its interaction with environmental conditions is unknown.
“This uncertainty is an impediment to the uptake of kikuyu pastures and those with kikuyu pastures can’t unlock their full potential because of the looming threat that the grass could spontaneously take out a herd of cattle.”
Kikuyu samples in a greenhouse before the DairyUP researchers created the environmental conditions that precede kikuyu toxicity.
Researchers from the NSW DairyUP program are investigating the cause of kikuyu toxicity by examining samples of grass and soil for signs where the “toxic” pasture varies from a “normal” sample.
Samples were collected from farms in the Hunter Valley affected by kikuyu poisoning in 2018-19 as well as others across NSW.
But more samples are always required.
Researchers are also recreating the environmental conditions that precede kikuyu toxicity in a greenhouse and testing different kikuyu varieties to see how they respond.
Krista said this greenhouse trial could identify genetic links to kikuyu toxicity or microbes that could be involved.
“Microbes that flourished under the artificial greenhouse ‘drought and rewater’ cycle, preceding kikuyu toxicity will be examined to see if they can be linked to past kikuyu toxicity,” she said.
“The kikuyu genetics will also be studied to understand how they may or may not contribute to resilience to toxicity.”
Kikuyu samples after DairyUP researchers have used a greenhouse to create the environmental conditions that precede kikuyu toxicity.
Krista has her sights set on a range of outcomes from this research — most notably prediction tools to evaluate pasture safety, the development of new kikuyu varieties that are less susceptible to toxicity events, in-field preventative treatments and treatments for affected cattle.
“The mystery of kikuyu toxicity has baffled scientists for 70 years,” she said.
“If we can narrow down some of the theories — even eliminate some — we will be closer to our target, and still advancing, to minimise kikuyu-associated cattle deaths and help farmers make better decisions.”
Anyone with information about kikuyu toxicity can contact Krista Plett at krista.plett@dpi.nsw.gov.au or on 0447 925 228.
