Veterinarians are urging producers to beware of grazing stock on stressed pastures and fodder crops after a recent outbreak of illness and deaths in cattle grazing kikuyu at Tyringham, west of Dorrigo.
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District Veterinarian, Dr Sarah Bolton, was called to a property on March 3 after receiving a report from a concerned landowner regarding sick and dying cattle.
The animals had been grazing a corn crop that had received a nitrogenous fertiliser application in December and had struggled during dry weather over the summer. The crop had also been subject to a recent army worm infestation and had received a small amount of rain during cloudy weather.
While grazing the corn, the animals did not appear to encounter ill-health, however once the corn was depleted, they began grazing kikuyu growing amongst the crop.
A number of animals were shortly found dead with several other animals showing signs that included drooling, lack of coordination, sunken eyes and sham drinking.
Given the history, Dr Bolton initially suspected nitrate toxicity. However, examinations of the sick animals combined with post mortem findings ruled out nitrate poisoning, with the presentation being classic for kikuyu toxicity.
"There are several situations in which plants that are normally considered safe, valuable grazing options can present a risk of toxicity," Dr Bolton said.
"Recent fertiliser application, along with dry weather causing plant stress then followed by rain increased the risk of diseases such as kikuyu poisoning, nitrate toxicity and bloat.”
It appears that when given the choice, cattle won’t eat affected kikuyu, with poisoning only occurring when they have no other options for grazing
- Dr Sarah Bolton
Cattle are most frequently affected however goats and sheep are also susceptible.
Researchers are still working to understand the exact cause of kikuyu toxicity, with investigations to date focusing on possible fungal causes however this is unconfirmed.
Unfortunately, there is no specific treatment available but affected stock can recover if removed from the toxic pasture and supportive care is provided.
Graziers can reduce the risk of toxicity by identifying high risk crops and pasture, avoiding introducing cattle while hungry and providing access to alternative feed.
“It appears that when given the choice, cattle won’t eat affected kikuyu, with poisoning only occurring when they have no other options for grazing.” Dr Bolton said.
