In 2025, drought stretched across southern Australia, impacting parts of New South Wales, Victoria, South Australia and central Western Australia. While spring showers eased conditions in some regions, New South Wales’s drought area has grown and extended into southern Queensland.
In addition to impacting feed availability, droughts also change biosecurity risks on your farm. Staying alert is essential to protect your livestock during this stressful period.
Diet changes can introduce risks
During a drought, pasture can become overgrazed and nutrient-deficient. This leads to temporary feeding changes, which can create new health and biosecurity challenges.
Grazing toxic plants
Over-grazed pasture can lead stock to consume unusual or harmful plants, such as:
- Bracken fern – this native perennial fern is found in the temperate regions of all Australian states except the Northern Territory. Prolonged consumption causes brain damage in sheep and horses, whereas in cattle it can cause clotting disorders, blood loss and cancer of the bone marrow and bladder.
- Lantana – found in coastal and subcoastal Queensland and New South Wales. Liver damage or death can occur in ruminants that have ingested the flowering plants, especially the orange/red flower variety (pink and white flower varieties are also toxic).
- Paterson’s curse – this invasive weed is found all over Australia, especially on degraded pastures where it’s at high risk of ingestion by grazing livestock. Ruminants can often break down the toxins without harmful effects, though prolonged ingestion may lead to liver damage. Pigs and horses can face chronic liver damage, loss of condition and sometimes death.
Supplemental feeding
To ensure nutritional demands are met, producers may start feeding or increase the amount of grain they feed to livestock. This brings added risks to biosecurity and animal health.
- Feed brought onto your farm can carry new pests and diseases. Always inspect the product and request a Commodity Vendor Declaration for food safety information on commodities intended for livestock feed.
- Over-feeding grain or transitioning ruminants from pasture too quickly will put them at high risk of ruminal acidosis. This is the most common cause of ruminant death during droughts. The high carbohydrate content can also cause an overgrowth of toxic gut bacteria, leading to diseases such as . Be sure to consult a veterinarian or animal nutritionist before implementing any major dietary changes.
Increased disease transmission risk
Droughts can contribute to increased disease transmission within your livestock and further disease spread across regions.
- Aim to provide animals with the maximum space possible and protect herd health by promptly separating out any animals that are displaying signs of disease.
- Droughts often mean more animal movement, such as for agistment or sale, which can spread diseases across regions. When restocking, follow the usual biosecurity precautions, such as requesting a National Animal Health Declaration, carefully inspecting new stock and quarantining them for 21 days to monitor for any signs of disease.
- Waterborne disease outbreaks can occur as water sources decline, become more stagnant, and are increasingly shared with wildlife and feral animals. Minimising potential points of contact between livestock and wildlife or feral species will help to mitigate this biosecurity threat.
Reduced immunity and disease susceptibility
Drought causes stress to livestock, which can result from multiple factors, including malnutrition, environmental changes, altered diets, and heat stress. Each of these challenges weakens the immune system, leaving animals more vulnerable to disease.
Acute infections that would normally be easily managed may become a serious health threat during a drought. Additionally, animals are at risk of developing chronic health conditions during extended dry periods, which can lead to poor health.
Producers should monitor stock closely for early signs of illness, maintain strong biosecurity measures and support animal health as much as possible through balanced nutrition and a well-informed drought plan.
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