The green pick available on swampy land or dried up billabongs and dams may seem a boon for producers during drought and difficult seasonal conditions.
However, it’s important to check for toxic weeds and plants in swampy areas before allowing stock access for grazing.
There are many plants that grow where the land is usually wet and rarely dried out which could cause issues.
Toxic plants that might be found in these areas include dock, soursob, fat hen, lesser loosestrife and swamp grass.
Many Dock (Rumex spp.) species such as swamp dock, curled dock and yellow dock, as well as Fat Hen (Chenopodium album) and Soursob (Oxalis pes-caprae), cause nitrate and nitrite toxicity and hyperoxaluria or oxalate toxicity.
Nitrate and nitrite toxicity can cause acute collapse and death once the nitrite binds to the haemoglobin in red blood cells, stopping the haemoglobin from carrying oxygen.
The mucous membranes inside an affected animal’s mouth may appear brown in colour due to this binding rather than the usual pink. There is no effective treatment for the condition.
Oxalate binds calcium up in the blood causing acute low blood calcium and sudden death. Calcium is essential for muscles to work properly. Early signs of oxalate toxicity include a stiff gait, staggering, lying down progressing to coma and death.
These weeds are not palatable so ensuring that stock are not put in hungry and have a wider forage area and supplementary feed available, will help to mitigate the risk.
Keep a close eye on your livestock and avoid putting grazing pressure on the site.
Lesser loosestrife (Lythrum hyssopifolia) is a native plant that grows well in wet and damp soils, such as swampy areas and stubble after rain. Depending on how much is eaten the toxin causes severe liver damage and death, within 24 hours up to several days later.
Affected stock will seem depressed, lethargic and show abdominal discomfort before progressing to recumbency and death. Loosestrife is not usually palatable to stock, though if there is no alternative green pick it will be eaten. If there is a large amount in the area, it is unsafe to place stock on it as the toxicity builds up.
Swamp grass (Glyceria maxima – Poa aquatica) is an introduced, very tall grass that occurs around water bodies and wetlands. It carries a very high level of cyanide in the leaves.
Due to the rapid effect of cyanide when ingested, poisoning causes acute collapse and death. Unlike nitrate and nitrite toxicity, the mucous membranes of the affected animals may appear bright pink, due to the body being unable to use the oxygen carried by the red blood cells. Swamp grass is unsafe as forage.
If you are putting stock onto a new area, thoroughly check for different species of plants, look at your records to see if anything happened last time it was used and ensure stock are not put on hungry which may cause them to forage indiscriminately.
If your livestock show signs of weed toxicity, remove them from the area and contact your veterinarian or local Animal Health staff for advice.
Across the state any farmer can access technical information and advice to help manage the impacts of increasingly difficult seasonal conditions.
These services will be delivered in partnership with a range of technical experts, including farm business advisors, livestock nutritionists, soil, water and pasture specialists and veterinarians.
The program provides tailored advice through one-on-one consultations, webinars, workshops, field days, and online tools and information.
Farmers anywhere in Victoria can register now for a one-on-one farm advisory consultation, to take stock and discuss the best way forward for their business.
The consultation includes a session of up to 3 hours (face to face on farm or online) and follow-up call, to develop and implement a drought management action plan.
When registering for the program, participants can indicate their preferred consultant from an extensive list of experienced service providers.
Find more information about available drought support at www.agriculture.vic.gov.au/drought or call 136 186.
Paul Beltz, Senior Veterinary Officer
