Climate changes affecting Australian livestock

In September 2023, the Bureau of Meteorology (The Bureau) declared an El Niño event was underway in Australia indicating a hotter and drier outlook, particularly for the eastern and southern states. Following this outlook and the very dry conditions experienced from August to October, many were surprised by the high amounts of rainfall and summer storms experienced in some regions. Interestingly, rainfall for January was actually above average for Australia as a whole.

Eastern and southeastern states received a deluge of rainfall and summer storms, which was largely influenced by the climate driver Summer Annular Mode (SAM). When SAM is in its positive phase, it is associated with increased summer rainfall in eastern states, although it is more commonly associated with La Niña years. As the El Niño weakened towards the end of January, ex-Tropical Cyclone Kirrily brought heavy rainfall across northern and western parts of Queensland, also reaching parts of central NSW before moving west towards Western Australia.

While the unexpectedly wet summer has been welcomed in some areas, the high rainfall may present challenges for livestock health and biosecurity. There are pathogens, pests and parasites that can thrive in warm and moist conditions. Listed below are a number of diseases to be on the lookout for based on the livestock species.

Sheep

Be on the lookout for:

• Footrot, particularly virulent footrot, is most commonly seen when conditions are warm and wet, with high soil moisture content.
• Fleece rot and fly strike, especially after heavy rain and floods.
• Barber’s pole worm, which favours warm and humid environments.

Further information:

• Sheep | Farm Biosecurity
• Footrot | Australian Wool Innovation

Beef cattle

Be on the lookout for:

• Nuisance flies and ticks, such as buffalo fly and cattle ticks (keeping in mind that rainfall may impact the effectiveness of pour-on treatments for flies and ticks).
• Bovine ephemeral fever (BEF).

Further information:

• Beef cattle | Farm Biosecurity
• Bovine Ephemeral Fever (BEF) | FlyBoss

Dairy cattle

Be on the lookout for:

• Facial eczema, is caused by a fungus that favours warm and moist conditions.

Further Information:

• Dairy Cattle | Farm Biosecurity
• Facial Eczema | Herd Health | Dairy Australia

Pigs and horses

Be on the lookout for:

• Japanese encephalitis virus ( JEV) is an arbovirus spread by mosquitoes, which can be transmitted to pigs, horses and humans.
• Following heavy rain, the conditions can become favourable for mosquito breeding.
• Other arboviral diseases may affect horses, including Murray Valley encephalitis and Kunjin, which are also spread by mosquitoes.

Further information:

• Mosquito Management for Horses | Farm Biosecurity
• Controlling mosquitos around piggeries | Farm Biosecurity

Another disease worth mentioning is anthrax, recently detected on a farm in Victoria. Anthrax outbreaks are rare, and usually limited to a region known as the ‘anthrax belt’ which includes parts of southern Queensland, central New South Wales and Victoria. The risk of anthrax is heightened by disturbed soil, such as after heavy rainfall or moderate rainfall following a long dry spell.

Long-range forecast

The Bureau is now forecasting a drier autumn for much of northern and eastern Australia, particularly for coastal regions. However, Autumn rainfall is also likely to be above median for interior parts of the country.

While long-range forecasts provide a valuable insight into approaching weather, it’s worth keeping in mind that the historical accuracy of these forecasts varies depending on the region. As we’ve seen from recent weather events this summer, it’s always useful to ‘expect the unexpected’.

• Overview—Climate influences – Climate Outlooks (bom.gov.au)
• Rainfall—Summary – Climate Outlooks (bom.gov.au)
• ABARES Weekly Australian Climate, Water and Agricultural Update (agriculture.gov.au)
• Anthrax factsheet | Biosecurity | Agriculture Victoria