[Department of Primary Industries Thursday 6 January 2011] -- Victorian
farmers are warned to be aware of the risk of exposing young sheep to the common
weed, lesser loosestrife (Lythrum hyssopifoli). Lesser loosestrife has
been found in many stubble paddocks across northern Victoria following the rain
during the current harvest period, and in most cases is the predominant weed
species present. This weed has caused large losses of young sheep many times in
past years when good spring and early summer rains have occurred and it is known
to have killed sheep across Victoria since 1974, with the most recent major
losses occurring in 2002 and 2009.
The plant contains an unidentified toxin which is capable of causing massive
damage to the sheep's liver and kidneys which may cause death in one or two
days. Other affected sheep can take up to three weeks to die, presumably having
eaten less.
The principal signs in affected sheep are severe abdominal pain, jaundice,
photosensitisation, loss of appetite, depression, lethargy and rapid weight loss
due to liver and kidney failure.
Sheep which die quickly often have large amounts of yellow clear fluid in
body cavities due to leakage from the damaged liver and body fat may show a
slight yellowing.
Most losses are generally seen in younger sheep. Older sheep are not as
commonly affected most likely due to their preference for other more palatable
weeds and the grain present in the stubble.
Lesser loosestrife prefers to grow in depressions and wetter areas of
paddocks, however rainfall events create good conditions for wide-spread growth.
Its growth is aided by cultivation and soil conditions that favour ease of
germination, hence its presence in stubbles.
If you have any questions or are concerned about losses that may have been
caused by lesser loosestrife or other summer weeds contact your local Animal
Health staff or the DPI customer service centre on 136 186.