Grazing Land Management

WA sheep producers warned of toxic weed and ryegrass risk

Sheep Central, November 25, 2020

WA sheep producers are urged to take preventative measures to protect their stock from worms and poisoning from toxic weeds like lesser loosestrife after recent rainfall.

SHEEP deaths from poisonous weeds and annual ryegrass toxicity has prompted a warning to Western Australia producers in rain-affected areas.

WA sheep producers whose properties received recent rainfall have been urged to monitor their flocks for signs of toxic weed and scour worm impacts.

The Department of Primary Industries and Regional Development has received recent reports of the weed lesser loosestrife and livestock deaths from annual ryegrass toxicity (ARGT) in the agricultural region.

The department’s Season 2020-21 webpages have been updated with the latest information on livestock management issues to help producers navigate the months ahead.

Department veterinarian Danny Roberts encouraged producers to take preventative measures and watch paddocks for weed outbreaks and symptoms of livestock poisoning.

“It is important for producers to inspect paddocks for weeds prior to introducing livestock, as well as nearby bush and scrub areas, which provide a microclimate for toxic weeds,” Dr Roberts said.

“In particular, lesser loosestrife weed, also known as Hyssop loosestrife, can be widespread in the agricultural region and cause liver and kidney damage to livestock.

“Watch for signs of depression, lethargy, weight loss, sensitivity to sunlight and, in severe cases, mortalities.”

Other toxic plants that could be a risk to livestock include caltrop, heliotrope, mintweed or goose foot, crown-beard, slender ice plant and native gastrolobium species.

Livestock affected by toxic plants should be moved from the suspect paddock immediately and provided with access to shade, fresh water and good quality hay.

Dr Roberts encouraged producers to be vigilant, as some toxins in weeds like heliotrope, were cumulative, while others only become toxic in certain conditions.

“Although many toxic plants are not palatable, hungry or sheep newly introduced to a property may be more susceptible.

“It is important to keep sheep well fed as a first line of defence with good access to green self-sown crop regrowth,” he said.

High incidence of ARGT bacteria detected

Higher number of paddocks infected with ARGT bacterium have been detected in the seed heads of annual ryegrass samples submitted to the department this season compared with 2019.

“This suggests high risk outbreaks of ARGT are possible across a wide area.

“Check sheep by driving slowly for 200 metres then stopping to elicit any signs of nervous behaviour,” Dr Roberts said.

Worm risk increased

DPIRD said the recent rainfall has also increased the risk of Barber’s pole, brown stomach and black worms, which could become a problem for weaners and hoggets over summer.

Dr Roberts said it was imperative for young sheep to be drenched in early December to ensure they don’t lose condition.

“The infective worm larvae will persist on drying pasture longer this year, particularly in paddocks with any green pasture in low lying areas,” he said.

“It is important weaned lambs and hoggets get a fully effective, combination drench by the first week of December, as any delay will affect young sheep going into summer.”

While ewes rarely suffer from Barber’s pole worm during summer, flocks located within 60 kilometres of the coast could be more susceptible – especially if further rainfall occurs during December.

“If there have been past outbreaks of Barber’s pole worm in adult sheep it is best to check worm egg counts in early December so confined mobs can be treated, if required,” Dr Roberts said.

Producers are encouraged to call their local private veterinarian or department veterinary officer to investigate when livestock are sick or call the Pest and Disease Information Service on (08) 9368 3080 or email [email protected].

More information about toxic weeds, scour worms, ARGT and flock management over summer is available from the department’s Season 2020-21 webpages or for more specific information search the website

Source – DPIRD.


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