Worms and scours can become a significant health problem in weaners and lambing ewes as they face the dual challenges of limited winter feed and cold stress.
Winter provides the ideal environmental conditions for worm larvae to survive on pastures.
When sheep are nutritionally stressed, in light condition, and grazing short pastures, they become highly susceptible to heavy worm burdens and subsequent scouring.
Livestock managers should consider worms as a primary suspect in any ill-thrifty or scouring sheep, regardless of how recently the flock was drenched.
To help establish whether worms are the root cause of poor performance or scouring, producers should evaluate:
– Nutrition: Current feed availability, the use of supplemental feeding, and overall stocking rates.
– Flock class and condition: The specific class of sheep and their current body condition scores.
– Drench history: The specific products used and the dates they were administered, paying close attention to the time elapsed since the last treatment.
To confirm a diagnosis, producers should submit faecal samples from at least five affected and five non-affected sheep for a formal worm egg count.
Effectively managing worm burdens through the colder months requires a combination of strategic feeding and regular monitoring:
– Pasture and nutrition: Ensure weaners and lambing ewes are provided with adequate feed on low-worm pastures. Ideal paddocks include those prepared by ‘smart grazing’ over summer, paddocks previously grazed by cattle, or those transitioning from crops.
– Condition scoring: Weaners and lambing ewes should ideally maintain a body condition score of around 2.5.
If animals fall below this benchmark, they require preferential treatment and targeted supplementary feeding.
– Regular testing: Monitor worm egg counts using a standard Wormtest (collecting samples from 10 representative sheep) every four to six weeks throughout winter.
– Pre-lambing checks: Assess worm egg counts in pregnant ewes approximately four weeks before lambing begins.
– Drench efficacy: Always confirm that a drench treatment has been effective by conducting a Wormtest at the time of drenching and repeating the test 10 to 14 days later.
For further information, producers can contact their local veterinarian, an Agriculture Victoria Animal Health Officer, or utilise the online tools available via WormBoss.
By Dr Jeff Cave, Senior Veterinary Officer, Agriculture Victoria
