Livestock owners should look for signs of blue-green algae when inspecting farm dams, troughs and other water sources, particularly during the warmer months, when algal blooms are more likely to occur.
Blue-green algae, also known as cyanobacteria, are bacteria that can multiply rapidly under certain conditions.
Blue-green algae is more likely to occur when the water is warm and enriched with nutrients like phosphorus or nitrogen.
While blue-green algal blooms typically appear as green paint-like surface scum in water, they can also be reddish-purple or brown in colour.
It can be difficult to tell blue-green algae from other less toxic algal species.
Blue-green algae may contain toxins that damage the liver or nervous system.
Drinking contaminated water can kill livestock quickly and a number of livestock may be affected at the same time.
Animals exposed to affected water supplies may continue to die over a prolonged period. In milder cases, productivity losses may occur, which in dairy cattle may be seen as decreased milk yield.
If a suspicious bloom is found, farmers should move their stock to an area on the property with a safe alternative water source.
Farmers should plan for managing water availability in the event that a blue-green algal bloom impacts their primary livestock drinking water supply.
The plan should include calculating how much water livestock would require if the primary water supply was unsafe to drink and identifying additional alternative on-farm water supplies that could be utilised quickly.
In the medium-term, your plan could include improving water reticulation systems, considering options for treating blue-green algae affected water, or agisting your stock elsewhere until your farm water is safe again.
A range of useful information such as the Blue-green algae: options for livestock drinking water factsheet is available from the Blue-green algae page on the website.
Alison Lee, Principal Veterinary Officer – Small Ruminants
