- Summer rains means gastro-intestinal worms are hitting sheep earlier than expected
- Worms can make WA livestock sick and reduce size and subsequent value
- Farmer should drench ewes two weeks before lambing to prevent lambs from getting worms
GREAT Southern sheep farmers are facing their toughest year of worm control in more than a decade thanks to widespread summer rains, according to an Albany livestock parasite specialist.
The rains have kick-started the life cycle of gastro-intestinal worms, including black scour worm (Trichostrongylus), brown stomach worm (Teladorsagia ostertagia) and barbers pole worm (Haemonchus contortus), Department of Agriculture and Food (DAFWA) principal veterinary officer Brown Besier says.
Worms thrive in warm, wet conditions, and cause significant productivity losses for the WA sheep industry by making animals sick and impacting their growth rates.
Grazing sheep contract worms by ingesting larvae that has hatched from eggs laid in the host animal’s intestinal tract by adult worms, which are passed through faeces and migrate onto pasture.
Some farmers have recorded “unprecedented” rainfalls between January and April—with gauges filling with more rain than they received last winter, Dr Besier says
“I can’t remember anything like this in at least 10 years,” he says.
“This is quite an exceptional situation.”
Because livestock have been exposed to worms several weeks earlier than usual, their infection risk is higher and farmers’ control methods will be less effective, Dr Besier says.
“Usually they would start seeing their first worm cases at the end of autumn or maybe well into winter, but this year they will see cases earlier and they will be more severe,” he says.
“Even without follow-up rain…the likelihood of worm problems will continue…because some worm larvae developing now will still be alive on the pasture in October and November.”
Vigilance is needed to keep ewes’ worm egg counts low before lambing starts in May, to avoid lambs contracting worms, Dr Besier says.
Barbers pole worm poses the biggest threat to flocks.
The parasite sucks the blood of their hosts and can cause anaemia and rapid death.
Cases have already been reported in Mt Barker, Narrikup and Manypeaks, among other areas.
“We normally wouldn’t see it at this time of year but it’s a concern,” he says.
“It’s a very prolific egg-layer and can increase its numbers quickly…it can go from not being noticed to a serious issue and stock losses.
“There is the potential for severe cases occurring from now up until June.”
Farmers are advised to drench ewes two weeks before lambing if their average egg count is above 100 eggs per gram of faeces, while weaned lambs should be drenched if their egg count average exceeds 300 eggs per gram.