Blue-green algae in farm water supplies
7 February 2019
Livestock owners need to be aware that seasonal conditions are ideal for blue-green algal growth in farm water supplies, which could result in poisoning of livestock as well as pets.
Victoria’s Acting Chief Veterinary Officer, Dr Cameron Bell, said blue green algae poisoning is usually seen in late summer and early autumn.
“Blue-green algal blooms typically appear as surface scum that looks like a suspension of green paint or curdled green milk. However, the colour may range from pale green to dark brown,” Dr Bell said.
“Often an ‘earthy’ smell will accompany a blue-green algal bloom.
“Deaths occur when stock drink toxins produced by the blue-green algae, often when it is concentrated on the down-wind side of a water supply and has formed a dense, surface scum.
“Animals that have consumed blue-green algal toxin may become ill very rapidly and die within 24 hours. Those that don’t die immediately often suffer severe liver damage. This may lead to the development of jaundice (the yellows) or photosensitisation over the next few days.”
Dr Bell said animals that recover from these ailments may then suffer from chronic ill-thrift.
He said there is no specific treatment for blue-green algae poisoning.
“Blue-green algal poisoning should be suspected when animals are found dead and dying after access to an algal contaminated water source. Dead animals may have their mouths, nose, feet and legs stained green by algae,” he said.
“Laboratory testing of the water supply for the presence of blue-green algae, and a post-mortem examination of dead or sick animals by a veterinarian, will confirm blue-green algal poisoning.
“Checking stock water supplies daily for blooms remains the most effective way of preventing stock deaths.”
Dr Bell said another way to help be prepared is to develop a livestock water budget so you know how much stock water you require per day. Don’t forget to allow for high consumption during the current hot conditions.
Identify an alternative water supply prior to the primary source of livestock drinking water being affected by a bloom. There may not be time to identify an alternative water source once the primary water supply is affected.
If a suspicious bloom is noticed, stock should be removed from the contaminated water source as quickly as possible, and a safe alternate water supply provided.
“It is also recommended to keep stock off pasture that has been irrigated with blue-green algae contaminated water for at least seven days after irrigation.”
Blue-green algae toxins may remain on dry pasture for some time following irrigation, often until there is a rain event or further irrigation with uncontaminated water.
Dr Bell said dogs are also prone to poisoning as they tend to swim in farm water supplies and therefore should be excluded from suspect water sources.
Accurate identification of algae should be sought to inform management of blooms in farm water supplies.
“If chemical water treatments are used, manufacturer instructions should be followed closely, as even more toxin may be released into the water supply as the algae die.
“This potentially makes the water even more toxic to livestock, and they should be removed from the water source until toxin is no longer present.”
For further advice please contact your local veterinarian or Agriculture Victoria Veterinary or Animal Health Officer, or in NSW, your Local Land Services.
Contact Name: Sarah Hetherington
Contact Number: 0409 405 639
Categorised under: Agriculture,Biosecurity,Pets